Jianguo Yu

The relationship between the oxygen species of cerium-based oxygen carriers and catalytic behavior, namely the correlation between catalytic activity and surface lattice oxygen (OS-L) and that between catalytic stability and bulk lattice oxygen (OB-L), was investigated by using CH3SH and Ce1-xYxO2-δ (x = 0, 0.25, 0.50, 0.75, and 1.0) solid solutions as examples. Activity and stability experimental studies with corresponding XPS were performed to assess the role of definite surface oxygen in cerium-based oxygen carriers. The surface lattice oxygen (OS-L), rather than the surface adsorbed oxygen (OS-A), was observed to be responsible for the catalytic decomposition of CH3SH. Further, the difference in catalytic activity between CeO2 and Y-doped samples is closely associated with the insertion of Y3+ ion into the lattice of CeO2 leading to the loss of surface lattice oxygen (OS-L). H2-temperature programmed reduction (TPR), a specially designed H2-TPR, X-ray photoelectron spectroscopy, reaction product (CO and CO2) analysis, and oxygen storage capacity tests were performed to demonstrate the migration of bulk lattice oxygen, which was directly related to the catalytic stability of CeO2 and Y-doped catalysts. Direct evidences of the migration of bulk lattice oxygen over cerium-based oxygen carriers were obtained. Additionally, the migration rate of bulk lattice oxygen (OB-L) within Ce0.75Y0.25O2-δ was faster compared to the migration rate of bulk lattice oxygen (OB-L) of CeO2. Finally, improvements in catalytic stability are closely associated with the fact that bulk lattice oxygen (OB-L) participates in the decomposition of CH3SH through its faster migration to replenish surface lattice oxygen (OS-L). The factors that influenced the migration rate of bulk lattice oxygen (OB-L) were thus also subsequently investigated and discussed.

Enhanced removal of phosphate by biomass-supported adsorbents is an effective and economic method to prevent the accelerated eutrophication in water body. A new nanocomposite Ws-N-La is fabricated for efficient phosphate removal by immobilizing “rod-like” nano-sized La(III) (hydr)oxides within a quaternary-aminated wheat straw (Ws-N). It exhibits higher adsorption capacity towards phosphate than the commercial IRA-900 or HFO-201 even at higher competing anions levels. The pH result indicated that the Ws-N-La would effectively sequestrate phosphate over a wide pH range between 3.0 and 7.0 without significant La(III) leaching. Ten cycles of adsorption-desorption experiments reveals that no significant capacity loss is observed, indicating excellent stability and repeated use property than any other La(III)-based adsorbents. The results of TEM, XRD and XPS analysis demonstrated that the formation of “needle-like” lanthanum phosphate nanoparticle is the dominant pathway for the specific adsorption of phosphate by nano-La(III) (hydr)oxides. All the results suggested that the biomass-supported nano-composite Ws-N-La can serve as a promising adsorbent for preferable phosphate removal in realistic application.

Easy-to-obtain magnetic bentonite-chitosan hybrid beads (Bn-CTS) were prepared by immobilizing bentonite within a porous structure of chitosan beads to achieve a hybrid adsorption effect for the removal of cesium ion (Cs+) from water. The hybrid adsorbent, which had a porous structure and abundant binding sites contributed by both chitosan and bentonite, ensured superb adsorption characteristics. The paramagnetic character of the beads enabled their facile separation for recycling. The chitosan/bentonite ratio, pH and contact time were optimized to achieve the optimal Cs+ efficiency, and the adsorption kinetics and isotherms were thoroughly discussed. The adsorption kinetics obeyed the pseudo-second-order model, and the best fitted equation for equilibrium data was the Langmuir isotherm model. The maximum adsorption capacity of the bentonite-chitosan beads was 57.1 mg g−1. The adsorbent had excellent selectivity towards Cs+ adsorption in the presence of abundant cations (Li+, Na+, K+ and Mg2+). The adsorbent was able to be recycled by treating the beads with 0.1 mol L−1 of MgCl2 to quantitatively desorb Cs+ from the beads. Overall, the magnetic bentonite-chitosan beads can be used as a highly efficient adsorbent for radioactive waste disposal and management.

The thermal decomposition mechanisms and the intermediate morphology of MgCl2·6H2O and MgCl2·H2O were studied using integrated thermal analysis, X-ray diffraction, scanning electron microscope and chemical analysis. The results showed that there were six steps in the thermal decomposition of MgCl2·6H2O: producing MgCl2·4H2O at 69 °C, MgCl2·2H2O at 129 °C, MgCl2·nH2O (1 ≤ n ≤ 2) and MgOHCl at 167 °C, the conversion of MgCl2·nH2O (1 ≤ n ≤ 2) to Mg(OH)Cl·0.3H2O by simultaneous dehydration and hydrolysis at 203 °C, the dehydration of Mg(OH)Cl·0.3H2O to MgOHCl at 235 °C, and finally the direct conversion of MgOHCl to the cylindrical particles of MgO at 415 °C. To restrain the sample hydrolysis and to obtain MgCl2·H2O, MgCl2·6H2O was first calcined in HCl atmosphere until 203 °C when MgCl2·H2O was obtained; HCl gas was then turned off and the calcination process continued, producing Mg3Cl2(OH)4·2H2O calcined at 203 °C, Mg3(OH)4Cl2 at 220 °C and MgO at 360 °C. The temperature of producing MgO from calcination of MgCl2·H2O was lower (360 °C) than that from MgCl2·6H2O (415 °C) because of its more reactive intermediate products: the irregular shape and tiny needle-like Mg3Cl2(OH)4·2H2O particles and the uneven surface porous Mg3(OH)4Cl2 particles. The MgO particles obtained at 360 °C had a flake structure.

A detailed framework for simulation of VPSA units is presented. Within this framework, a detailed description of the adsorbent column is provided and linked with other ancillary parts of the unit. This modeling strategy is particularly suitable to demonstrate how the entire unit works and to identify operating constraints that may be caused by ancillary equipment. In order to apply this strategy to a practical example, we have simulated different cycles of VPSA processes using zeolite 5A for CO2 capture from a mixture with 15% CO2–85% N2 (resembling post-combustion flue gases of a coal-fired power station). Simulations of VPSA units with two, three and four columns and different cycle configurations were carried out. Inclusion of a rinse step was necessary to improve CO2 purity. However, using a single VPSA unit, it was not possible to achieve purity higher than 77% and for this reason a two-stage VPSA unit was simulated. The two-stage VPSA simulations include a three-column front VPSA process where CO2 purity is increased to 70% and then this gas is recompressed to a second, tail two-column VPSA unit where CO2 purity increases to 96%. The overall unit productivity of this process is 0.0146 kgCO2/(kgads h) with an energy consumption of 645.7 kJ/kgCO2.

Knowledge of adsorption equilibria and kinetics of pure gases is required for designing an adsorption process for a new material that can be scaled-up to large amounts. In this work, adsorption equilibrium data of CO2 and N2 on pitch-based activated carbon (AC) beads at 303, 333, 363, 393, and 423 K ranging from 0 to 100 kPa and at 303, 333 K ranging from 0 to 4000 kPa were presented. The adsorption capacity is 1.918 mol/kg for CO2 and 0.270 mol/kg for N2 at 303 K and 100 kPa. The full set of data was fitted with both Virial adsorption equation and multisite Langmuir model. The diffusion of single gases in the microporous structure of AC beads was studied by diluted breakthrough experiments performed over the same temperature range of 303–423 K. A mathematical model was employed in the simulation of breakthrough curves. It was determined that for CO2 and N2, the controlling mechanism is micropore diffusion. The micropore diffusivity constant (Dc/rc2) for carbon dioxide and nitrogen obtained at 303 K is 1.058 × 10−2 and 7.185 × 10−2 s−1, respectively. The data reported in this work allows modeling of any adsorption processes with this new material.

Zeolite 13X-APG with Si/Al ratio of 1.23 supplied by UOP (China) was evaluated for capturing the low concentration CO2 from flue gas. The adsorption equilibrium isotherms of CO2 and N2 on this adsorbent were measured at various temperatures (303, 333, 363, 393)K with 0–1 bar range of pressure and the experimental data were fitted by the multi-site Langmuir model. Compared with the conventional NaX zeolite, 13X-APG zeolite has an excellent adsorption capacity to CO2, especially at low CO2 partial pressure. The adsorbent is more selective to CO2 in the flue gas. The breakthrough experiments of CO2 and N2 in the column packed with zeolite 13X-APG pellets have been studied. A mathematical model based on the bi-LDF approximation for mass transfer, taking into account the energy and momentum balances, have been employed in the simulation of breakthrough curves in order to obtain the adsorption kinetic parameters of CO2 and N2, respectively. The experimental and theoretical results of a six-step hybrid VTSA process, as well as four-step VSA and five-step TSA process were presented for CO2 capture at ambient temperature and ambient pressure from the simulated flue gas (85% N2 and 15% CO2), and the feasibility and efficiency of VTSA process were analyzed. The regeneration conditions of VTSA process became more gentle when compared with the cases in both VSA and TSA processes, and it would be a saving power-energy consumption process for post-combustion CO2 capture if it was retrofitted to the existed power plants with the utilization of the lower grade heating/cooling source.

CO2 capture and storage (CCS) is an effective method for achieving CO2 mitigation while simultaneously keeping energy supplies secure. To put CCS into practice, it is important to develop energy-efficient industrial technologies for CO2 capture. In this work, a pilot-scale demonstration of carbon capture from flue gas by adsorption technology was performed in an existing coal-fired power plant in China, and the power energy consumption to capture 1 kg of CO2 was measured onsite; furthermore, the feasibility and efficiency of adsorption technology for postcombustion CO2 capture were investigated. The pilot-scale carbon capture plant consisted of two successive VPSA units coupled with a dehumidifying unit. In the dehumidifying unit, water vapor in the desulfurized flue gas was removed by alumina adsorption. Then, CO2 in the dehumidified flue gas was captured by two successive VPSA units, where the three-bed eight-step VPSA process was employed in the first unit packed with zeolite 13X APG, and the second two-bed six-step VPSA unit was packed with pitched activated carbon beads. A roots blower was used to supply the desulfurized flue gas to the pilot-scale carbon capture plant at a controlled flow rate, and both a reciprocating pump and a diaphragm pump were employed to desorb adsorbents under vacuum pressure in the two-stage units and recover high-purity CO2 for subsequent storage or utilization. Some key assessment parameters were measured onsite, including the flow rate of flue gas, CO2 recovery from flue gas, CO2 purity in the product gas, and power energy consumption to capture 1 kg of CO2, and the experimental results were verified by numerical simulations using a multibed VPSA modeling framework. Based on the experimental and simulated results, CO2 capture from flue gas in an existing coal-fired power plant by two successive VPSA units was evaluated.

Carbon dioxide removal from flue gas with a two-stage vacuum pressure swing adsorption (VPSA) process, which uses activated carbon (AC) beads as the adsorbent, was investigated both theoretically and experimentally. First, single-column VPSA experiments were studied for CO2/N2 separation with high CO2 feed concentration. Then, a two-stage VPSA process composed two columns for each stage was designed, and the effects of different parameters were investigated. The first-stage VPSA unit operates with a four-step Skarstrom cycle, which includes feed pressurization, adsorption, blowdown, and counter-current purge with N2. For the second-stage VPSA process, a cycle with feed pressurization, adsorption, pressure equalization, blowdown and pressure equalization was employed. With the proposed two-stage VPSA process, a CO2 purity of 95.3% was obtained with 74.4% recovery. The total specific power consumption of the two-stage VPSA process is 723.6 kJ/kg-CO2, while the unit productivity is 0.85 mol-CO2/kg·h.

A series of rare earth elements with different ionic radii (RE = Gd, Sm and Nd) doped ceria solid solutions and pure ceria catalyst were rapidly prepared by citrate-complexation method. These catalysts were evaluated for catalytic decomposition of methyl mercaptan as a model odorous sulfur containing pollutant. According to the XRD, Raman, XPS, H2-TPR, OSC, FT-IR and CO2-TPD characterization results, the radius of RE cation played an important role in determining the structural and surface characteristics of RE doped ceria catalysts, which could affect the catalytic stability for CH3SH decomposition. Thereinto, Ce0.75Gd0.25O2-δ, with a moderate increase in the alkalinity, possessed more oxygen vacancies. More of structural defects and active sites could be provided, which should be in favor of improving catalytic stability. But for Ce0.75Nd0.25O2-δ, with too many basic sites, more of active sites would be occupied and plenty of cerium sulfide species (Ce2S3) would be accumulated on the catalyst during the reaction processes. The accumulation of Ce2S3 mainly caused the deactivation of catalyst. The catalytic stability of Ce0.75Sm0.25O2-δ was comparable to that of CeO2, which might be resulted from the combined effect of the increased oxygen vacancies and basic sites.

The adsorption equilibriums of CO2, CH4, and N2 pure gases on pitch-based activated carbon beads have been studied using a magnetic suspension microbalance at (293, 303, 333, and 363) K within a pressure range of 0 kPa to 4000 kPa. It is found that experimental adsorption capacities can be successfully described with both the Sips and Multisite Langmuir (MSL) isotherm models. Afterward, binary competitive adsorption breakthrough experiments (CO2/CH4 and CH4/N2) at 303 K and adsorption isotherms of gas mixtures under different conditions have been measured. Theoretical calculations from Sips model-based ideal adsorbed solution theory are found to have better agreement with experimental data of competitive binary adsorption than that from MSL model. Promising adsorption selectivity (5.5) between CH4 and N2 is obtained at 303 K as the pressure of a binary gas mixture is 100 kPa with yCH4 = 0.5 in the feed. Therefore, the activated carbon beads reported in this study can be considered as a promising adsorbent for CH4 enrichment from coalbed methane (CH4/N2) gas mixture.

In eutrophic lakes, the decay of settled algal biomass generates organic carbon and consumes oxygen, favoring sediment nitrogen loss via denitrification. However, persistent winds can cause algae to accumulate into dense mats, with uncertain impacts on sediment nitrogen removal. In this study, we investigated the effects of algal accumulation on sediment nitrogen removal in a shallow and eutrophic Chinese lake, Taihu. We found that experimental treatments of increased algal accumulation were associated with decreased sediment nitrogen losses, indicating the potential for a break in coupled nitrification-denitrification. Likewise, field measurements indicated similar decreases in sediment nitrogen losses when algal accumulation occurred. It is possibly caused by the decay of excess algal biomass, which likely depleted dissolved oxygen, and could have inhibited nitrification and thereby denitrification in sediments. We estimate that if such algal accumulations occurred over 20% or 10% of lake area in Taihu, sediment nitrogen removal rates decreased from 835.6 to 167.2 and 77.2 μmol N m-2h-1, respectively, during algal accumulation period. While nitrogen removal may recover later, the apparent nitrogen removal decrease may create a window for algal proliferation and intensification. This study advances our knowledge on the impacts of algal blooms on nitrogen removal in shallow eutrophic lakes.

Long-root Eichhornia crassipes has shown great remediation capacity for eutrophication while the dispose of massive plants reaped is a pressing challenge for its large-scale application. In this study the waste plants were reclaimed and employed to prepare multi-pore activated carbons (MPAC) with high specific surface area through a simple gradient heating method. Owing to the large specific surface area and abundant multiple functional groups, the MPAC exhibited great adsorption performances for heavy metals with great adsorption capacities and rapid rate. Careful adsorption investigation indicated that the adsorption was mainly controlled by a charge transfer complex pattern. In addition, the adsorption impetuses were heterozygous involving electrostatic interaction, electron sharing or electronic-donor-acceptor interaction, etc. Moreover, the competitive adsorption reflected adsorption preference existed in the heavy metal removal using the MPAC as adsorbents due to the imparities in the adsorption affinity, thus resulting in the differences of the adsorption tolerance to exogenous influence.

Single-atom catalysts have been extensively studied due to the high atom utilization efficiency. However, the atomically dispersed dual-metal-site material for bifunctional catalysis in zinc-air battery is still rare. Herein, taking advantage of the trapping ability of graphene oxide to anchor metal ions, a dual-metal-site bifunctional catalyst with atomically dispersed FeN4 and NiN4 in the nitrogen doped graphene (Fe/Ni(1:3)-NG) is developed. Benefiting from the synergy effect between Fe and Ni, the catalytic performance can be greatly enhanced. The resultant catalyst exhibits highly efficient bifunctional catalytic activity, with the half-wave potential of 0.842 V for oxygen reduction reaction (ORR) and an overpotential of 480 mV at the current of 10 mA cm-2 for oxygen evolution reaction (OER). On the basis of bifunctional catalytic activities, the Fe/Ni(1:3)-NG based zinc-air battery shows an excellent power density (164.1 mW cm-2), outstanding specific capacity (824.3 mAh g-1) along with the prominent durability.

In order to explore the pollutant removal performance and interspecific interaction in constructed wetland (CW) with Fe0-C filler, constructed wetland with Fe0-C filler (CW-Fe) and with ceramsite filler (CW-C) were set up. Besides, the nutrients removal and interspecific interaction were analyzed, and the results showed that total nitrogen (TN) removal efficiency of CW-Fe system without carbon source was lower than that in CW-C system though CW-Fe system could convert macro-molecular organic matter into micro-molecular organic matter. However, ammonia nitrogen (NH4+-N) increase was observed in CW-Fe system with better total phosphorus (TP) removal performance. High-throughput sequencing showed that the microbial richness and abundance of Bacteroides, Firmicutes, Chlorofeli and Actinobacteria in the CW with Fe0-C filler was significantly higher than with ceramsite filler. The interaction between two CWs was significantly different, and the functional enzymes abundance of nitrate nitrogen (NO3--N) to NH4+-N transformation in CW-Fe system significantly increased.

Praseodymium (Pr) promoted Ni/Al2O3 catalysts with multiple Pr6O11 stabilized Ni0/NiO structure are synthesized by varying amounts of Pr and Ni using co-incipient wetness impregnation method and are investigated for hydrogen production via methanol steam reforming. Various technique, such as, XRD, H2-TPR, in-situ XPS, HRTEM and Raman, are used to characterize those materials. Characterization results show that Pr species is presented in the form of Pr oxide after reduction, and the geometrical and electronic action of Pr oxide on NiO species leads to the formation of multiple Pr6O11 stabilized Ni0/NiO structure, which promotes the low-temperature catalytic performance. Compared with Ni/Al2O3, 10 wt.% Pr promoted Ni catalyst exhibits the longer-term stability owing to the strong inhibition to the aggregation of metallic Ni0 particles, originating from the synergistic effect of Pr oxide on immobilization the metallic Ni0 particle and its size distribution as well as on the electronic role of Ni0/NiO species.

The aquatic plants Iris pseudacorus L., Canna indica L. and Lythrum salicaria L. have been proved to be potential choices for nitrogen removal. However, little is known about microbial diversity for the improvement of nitrogen removal (nitrification and denitrification) in stormwater bioretention cells with the above plants. In this study, batch experiments were conducted to investigate nitrogen removal, substrate layer status, and bacterial community structure to understand microbial diversity and evaluate its effects on performances of nitrogen removal. Ammonia nitrogen removal in the bioretention cell with Lythrum salicaria L. was the highest (88.1%), which was consistent with oxidation reduction potential (ORP) in the bioretention cells. Whilst, removals for both total nitrogen and nitrate were the highest in the bioretention cell with Canna indica L., which was in line with urease activity in the mentioned cells. The used plants had different impact on top 11 dominant microflora at phylum level in the used bioretention cells. Ramlibacter and Nitrosomonadaceaea were both responsible for the difference of nitrogen removal in the bioretention cells with three aquatic plants, suggesting the enhancement of the above dominant microflora could strengthen nitrogen removal in the used bioretention cells.

Sequential extraction and in-situ diffusive gradients in thin films (DGT) techniques were used to determine phosphorus (P) fractions and high-resolution 2D fluxes of labile PDGT, Fe2+DGT, and S2−DGT in sediment systems. The diffusion fluxes were subsequently calculated for different scenarios. Dynamic diffusion parameters between solid sediment and solution were also fitted using the DIFS (DGT-induced fluxes in sediments) model. The results suggested that Fe-bound P (Fe-P) was the dominant pool which contributed to the resupply potential of P in the water–sediment continuum. Significant upward decreases of labile PDGT, Fe2+DGT, and S2−DGT fluxes were detected in pristine and incubated microcosms. This dominance indicated the more obvious immobilization of labile P via oxidation of both Fe2+ and S2− in oxidic conditions. Additionally, these labile analytes in the microcosms obviously decreased after a 30-day incubation period, indicating that water-level fluctuations can significantly regulate adsorption–desorption processes of the P bound to Fe-containing minerals within a short time. Higher concentrations of labile PDGT, Fe2+DGT, and S2−DGT were measured at the shallow lake region where more drastic water-level variation occurred. This demonstrates that frequent adsorption–desorption of phosphate from the sediment particles to the aqueous solution can result in looser binding on the solid sediment surface and easier desorption in aerobic conditions via the regulation of water levels. Higher R values fitted with DIFS model suggested that more significant desorption and replenishment effect of labile P to the aqueous solution would occur in lake regions with more dramatic water-level variations. Finally, a significant positive correlation between S2−DGT and Fe2+ DGT in the sediment indicated that the S2− oxidization under the conditions of low water-level can trigger the reduction of Fe(III) and subsequent release of active P. In general, speaking, frequent water-level fluctuations in the lake over time facilitated the formation and retention of the Fe(II) phase in the sediment, and desorption of Fe coupled P into the aqueous solution when the water level was high.

As a regular neurodegenerative disease, Parkinson's disease (PD) brings great pain and heavy economic burden to patients. Peroxynitrite (ONOO - ) have attracted great attention to be a neurotoxicity specie in the pathogenesis of PD. Therefore, understanding the physiological functions of ONOO - in PD disease is of great importance to the early diagnoses. Unfortunately, it still lacks effective method for detecting ONOO - in PD model. In this work, a highly sensitivity and selectivity near-infrared ratiometric fluorescent probe (named K-ONOO ) was designed for tracking ONOO - in PD model. K-ONOO exhibited a unique ratiometric response toward ONOO - due to the fracture of the boronic acid ester group and the principle of ICT resulted in red-shifted spectra. K-ONOO exhibited a quantitative response to ONOO - (0–15 μM) with a low detection limit (212 nM). K-ONOO can successfully map the changes of endogenous ONOO - in vivo. The results demonstrated that an elevated degree of ONOO - is closely correlated with zebrafish under rotenone stimulation. More importantly, H 2 S may serve as a neuroprotectant, which helps regulate ONOO - overexpression and prevent oxidative stress-induced neurodegeneration. The visualization imaging of ONOO - based on K-ONOO provides an auspicious method for understanding the essential role of ONOO - during PD disease pathology and early diagnosis. • A NIR fluorescent probe K-ONOO with ratiometric characteristic for imaging ONOO - in PD model was reported. • K-ONOO is the first NIR ratiometric fluorescent probe for imaging ONOO - in PD model. • K-ONOO displayed high specificity toward ONOO - over other reactive oxygen species with a fast response. • K-ONOO was successfully applied for monitoring the fluctuation of ONOO - in PD model. • H 2 S may serve as a latent neuroprotectant to prevent neurotoxin-induced neurodegeneration.

For investigating the microbial community, interspecific interaction and nitrogen metabolism during the transform process from heterotrophic to synergistic and autotrophic denitrification, a filter was built, and carbon source and sulfur concentration were changed to release the transformation process. The results demonstrated that the transformation process was feasible to keep nitrate nitrogen (NO3--N) discharge concentration lower than 15 mg L-1, however, nitrite nitrogen (NO2--N) accumulation and its rate reached 7.85% at initial stages. The dominant denitrification gunes were Methylophilaceae, Thiovulaceae and Hydrogenophilaceae for three processes, respectively, and the microbial interspecific interaction of heterotrophic denitrification was more complex than others. NO2--N accumulation was confirmed by the low abundance of EC1.7.7.1 and EC1.7.2.1, and the dominance degree of dark oxidation of sulfur compounds and dark sulfide oxidation improved in synthesis and autotrophic denitrifications.

To improve H2O2 generation and Fe3+/Fe2+ cycle simultaneously for enhancing Electro-Fenton performance, the electrode aeration (EA) and hydroxylamine sulfate (HA) were coupled. With dimethyl phthalate (DMP) as main target contaminant, combination of HA and EA greatly accelerated the degradation of DMP and exhibited a synergy in the pH of 2.0-6.9 through promoting the key reactions, including electrochemical two-electron reduction of O2 into H2O2 and redox cycles of Fe3+/Fe2+, which then improved the generation of hydroxyl radicals (·OH). The coupling EA and HA reduced the use of HA and converted most of HA into environment-friendly N2 (60.1-62.1% of HA products), while HA/solution aeration(SA) system consumed HA rapidly and the generated N2 only accounted for 5.8-6.7% of HA products. Furthermore, compared with HA/SA and EA Electro-Fenton systems, enhancement degree of DMP degradation in HA/EA Electro-Fenton process was higher in actual waterbody than in ultrapure water. The coupling EA and HA in the Electro-Fenton process could solve the low Fe3+/Fe2+ cycle efficiency and low H2O2 production simultaneously, and improve the N2 selectivity of HA transformation, which advanced its application in practical environmental remediation.

Intracellular pH is one of the important parameters of cellular metabolism. The function of mitochondria is highly dependent on pH. Developing ratiometric fluorescent probes with suitable alkaline pKa for the detection of mitochondrial pH is urgently demanded. Herein, a mitochondria-targeted ratiometric pH fluorescent probe SNRF was designed based on 1,6-dihydroxynaphthalene and 4-diethylaminoketo acid. SNRF contains a hydroxyl electron donor and a nitrogen positron acceptor with excellent molecular charge transfer (ICT) performance. The hydroxyl group is a pH-sensitive group, which is prone to be protonated under acidic conditions and deprotonated under alkaline conditions. The ratiometric performance of SNRF can avoid the interference from instrumental factors, concentration of probe and microenvironment around the probe. SNRF exhibits a suitable pKa (8.30) with a linear variation between pH 7.4–9.0, making it ideal for monitoring mitochondrial pH changes. And, SNRF can be used to detect pH changes in HeLa cells and zebrafish without interference from other biologically active molecules. Furthermore, SNRF showed excellent mitochondrial targeting and was successfully used to track pH changes during rapamycin-induced mitophagy.

To evaluate the effect of Fe3+ on nitrogen (N) removal and associated microbial characteristics during simultaneous chemical phosphorus (P) removal, a sequencing batch reactor was used to analyze the changes in the microbial community and metabolic pathways caused by Fe3+ addition. Results demonstrated that Fe3+ promoted ammonia nitrogen (NH4+-N) removal and inhibited denitrification process, and increased the sludge particles (D50) and the biomass per sludge particle size. Furthermore, the abundances of denitrifying bacteria (Haliangium and Terrimonas) and biological phosphorus removing bacteria (Halaingium, norank_f_Saprospiraceae and SM1A02) were decreased. On the contrary, the increase of nitrifying bacteria abundance and the coding genes of nitrification-related enzymes confirmed the promotion for nitrification with Fe3+ addition. Besides, Fe3+ inhibited the interspecific relationship between denitrifying bacteria genera and other genera to reduce denitrification efficiency.

A two-stage tidal flow constructed wetland (referred to as TFCW-A and TFCW-B) was used to treat low chemical oxygen demand/total nitrogen (COD/TN or simply C/N) ratio influent at low temperatures (<15 °C). The influence of the flooding-resting time (A: 8 h–4 h, B: 4 h–8 h) and effluent recirculation on nitrogen removal and microbial community characteristics were explored. TFCW-B achieved optimal average nitrogen removal efficiency with effluent recirculation (96.05% ammonium nitrogen (NH4+-N); 78.43% TN) and led to nitrate nitrogen (NO3−-N) accumulation due to the lack of a carbon source and longer resting time. Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were inhibited at low temperatures. Except for nrfA, AOA, AOB, narG and nirS were separated by the flooding-resting time rather than by spatial position. Furthermore, the dominant genera in TFCW-A were Arthrobacter, Rhodobacter, Pseudomonas, and Solitalea, whereas prolonging resting time promoted the growth of Thauera and Zoogloea in TFCW-B. Spearman correlation analysis showed that Zoogloea and Rhodobacter had the strongest correlations with other genera. Moreover, the NH4+-N concentration was significantly positively influenced by Arthrobacter, Rhodobacter, Pseudomonas, and Solitalea but negatively influenced by Thauera and Zoogloea. There was no significant correlation between TN and the dominant genera. This study not only provides a practicable system for wastewater treatment with a low C/N ratio but also presents a theoretical basis for the regulation of microbial communities in nitrogen removal systems at low temperatures.

Microplastics (MPs), a new class of emerging pollutants, have attracted exponentially increased attention due to the adverse ecological impacts on biota, not only by themselves but also by the combined corrosive substances. However, the occurrence mechanisms, numerical models and influencing factors of MPs adsorbing organic pollutants (OPs) show a significant variation with literatures. Therefore, this review is focused on the adsorption of OPs on MPs, including mechanisms, numerical models, and influencing factors, to obtain a comprehensive understanding. Research shows that MPs with strong hydrophobicity have high adsorption capacity for hydrophobic OPs. Hydrophobic distribution and surface adsorption are considered to be the main mechanisms by which MPs adsorb OPs. The available literature suggests that the pseudo-second-order model describes the adsorption kinetics of OPs on MPs better than the pseudo-first-order model, while the choice of Freundlich or Langmuir isotherm model depends mainly on the specific environmental conditions. Moreover, the characteristics of MPs (composition, particle size, aging, etc.), the nature of OPs (concentration, polarity, hydrophilicity, etc.), the environmental conditions (temperature, salinity, pH, ionic strength, etc.), and the substances co-existing in the environment (e.g., DOM and surfactants) are all important factors affecting the adsorption behavior of MPs for OPs. Environmental conditions can also indirectly affect the adsorption of hydrophilic OPs adsorbed on MPs by causing changes in the surface properties of MPs. Based on the current knowledge, the perspective shortening the knowledge gap is also suggested.

Nitroxyl (HNO) and endoplasmic reticulum (ER) stress are considered to play important effects in the administration of many pathological processes of Parkinson’s disease (PD). However, the intricate relationship between the neurotoxicity of HNO and ER stress in the processes of PD is still unknown. To completely comprehend the pathogenic activity of HNO during ER stress and achieve early diagnosis of PD, developing sensitive tools for HNO sensing in vivo is essential. In this work, a two-photon fluorescent probe (KD-HNO) was developed with highly selective and sensitive (7.93 nM) response for HNO in vitro. Then, utilizing KD-HNO, we found that HNO levels were distinctly increased in tunicamycin-stimulated PC12 cells, which are characterized by ER stress and PD features. Most importantly, we detected a considerable increase in HNO levels in the brains of PD-model mice, indicating a positive correlation between PD and HNO levels for the first time. Collectively, these findings revealed that KD-HNO is an excellent tool not only for understanding the biological effects of HNO in pathological processes of PD but also for early PD diagnosis.

Parkinson's disease (PD) is a neurodegenerative disease common in middle-aged and older individuals. At present, the exact cause is unknown, and the diagnosis is cumbersome, which seriously hinders the early diagnosis of patients. During the same time, during PD, there are conditions for the formation of nitroxyl (HNO). In addition, it has been shown that HNO has toxic effects on dopaminergic neurons and can lead to depletion of Glutathione (GSH), which is associated with features of PD. Therefore, HNO could be used as a potential biomarker for PD. Unfortunately, studies on changes in HNO content during PD are rarely reported. Here, we synthesized the first near-infrared ratiometric fluorescent probe HX-HNO for detecting HNO content in a PD model. The probe has excellent selectivity and sensitivity, and can detect HNO produced in various biochemical processes. Most importantly, in a PD model generated by rotenone, HX-HNO detected elevated levels of HNO. The visualization of HNO by HX-HNO provides a powerful tool for the early diagnosis of PD.

A carbazole thiophene-aldehyde and 4-methylbenzenesulfonhydrazide conjugate CSH was synthesized by introducing 5-thiophene aldehyde at the 3-position of the carbazole group as the precursor and then condensing it with 4-methylbenzenesulfonhydrazide. CSH has high selectivity and sensitivity towards ClO-, which can specifically identify ClO- by UV-Vis and fluorescence spectroscopy. CSH can rapidly respond to ClO- in the physiological pH range through a fluorescence quenching pattern, accompanied by the color of CSH changing markedly from turquoise to yellowish green under the 365 nm UV light. Probe CSH exhibits a quantitative response to ClO- (0–11 μM) with a low detection limit (1.16 × 10-6 M). Cell imaging experiments have shown that CSH can capture fluorescent signals in the cyan and yellow channels of HeLa cells through fluorescence confocal microscopy, and can successfully identify exogenous ClO- in HeLa cells. In addition, probe CSH can also be used to detect ClO- in environmental water samples. These results indicate that CSH has potential application prospects in the environmental analysis and biological aspects.

The generalized energy-based fragmentation (GEBF) approach (Li, W.; Li, S.; Jiang, Y. J. Phys. Chem. A 2007, 111, 2193) is extended for geometry optimizations and vibrational spectra calculations of general large molecules or clusters. In this approach, the total energy and its derivatives, and some molecular properties, of a target system are obtained from conventional calculations on a series of subsystems derived from the target system. Each subsystem is electronically embedded in the background point charges generated by all other atoms outside the subsystem so that the long-range interactions and polarization effects between remote fragments are approximately taken into account. The approach computationally scales linearly with the system size and can be easily implemented for large-scale parallelization. By comparing the results from the conventional and GEBF calculations for several test molecules including a polypeptide and a water cluster, we demonstrate that the GEBF approach is able to provide quite reliable predictions for molecular geometries, vibrational frequencies, and thermochemistry data and satisfactory descriptions for vibrational intensities, for general molecules with polar or charged groups.

The stability, thermal and mechanical properties of PtxAly intermetallic compounds are investigated by density functional theory (DFT). The cohesive energy and formation enthalpy of PtxAly phases show that they are thermodynamically stable structures and these are in good agreement with the experiments. The heat capacity of the compounds is calculated by quasi-harmonic approximation (QHA) method. The thermal expansion coefficient as a function of temperature for each compound is also discussed. The elastic properties such as bulk modulus, Young’s modulus are evaluated by Viogt–Reuss–Hill approximation. The anisotropic properties of sound velocities for the PtxAly compounds are explored. The calculated Poisson’s ratio varies from 0.26 to 0.39 for PtxAly phases and the bonds in the compounds are mainly metallic and covalent types.

Acetylene hydratase is a tungsten-dependent enzyme that catalyzes the nonredox hydration of acetylene to acetaldehyde. Density functional theory calculations are used to elucidate the reaction mechanism of this enzyme with a large model of the active site devised on the basis of the native X-ray crystal structure. Based on the calculations, we propose a new mechanism in which the acetylene substrate first displaces the W-coordinated water molecule, and then undergoes a nucleophilic attack by the water molecule assisted by an ionized Asp13 residue at the active site. This is followed by proton transfer from Asp13 to the newly formed vinyl anion intermediate. In the subsequent isomerization, Asp13 shuttles a proton from the hydroxyl group of the vinyl alcohol to the α-carbon. Asp13 is thus a key player in the mechanism, but also W is directly involved in the reaction by binding and activating acetylene and providing electrostatic stabilization to the transition states and intermediates. Several other mechanisms are also considered but the energetic barriers are found to be very high, ruling out these possibilities.

The feasibility and efficiency of adsorption technology were evaluated experimentally and theoretically for CO2 capture from the flue gas in an existing coal-fired power plant, where a three-bed VPSA unit was set up to test 282 kg of adsorbent materials. In this work, the experimental results are reported for zeolite 5A as the adsorbent. The composition of the flue gas after dehydration was 15.0 vol % CO2, 76.5 vol % N2, and 8.5 vol % O2. With a three-bed seven-step VPSA process including rinse and pressure equalization steps, 85% CO2 was obtained with recovery of 79% from flue gas at a feed flow rate of 46.0 Nm3/h. The experimentally measured energy consumption was 2.37 MJ/(kg of CO2). The experimental work was compared with numerical simulations through the multibed VPSA modeling framework developed in a previous work. The simulated results were found to agree well with the experimental results.

P4O10 is highly deliquescent and reactive; techniques using non-P4O10 process are not only required for environmental protection, but also for consideration of safety and cost in industrial-scale production. A non-P4O10 process to prepare ammonium polyphosphate with crystalline form II (APP-II) was proposed by heating the mixture of diammonium hydrogen phosphate (DAP) and melamine under wet ammonia. Its water solubility, FT-IR, XRD, and 31P NMR spectra were compared with those of commercial APP-II and melamine polyphosphate (MPoly), and interesting results were obtained. Thermogravometric analysis (TGA) showed the synthesized APP-II had better thermal stability than commercial APP-II. The reaction mechanism and molecular structure for the subject compound were investigated and discussed in detail.

The effects of sodium dodecyl sulfonate (SDS) and sodium dodecyl benzene sulfonate (SDBS) on the morphology of calcium sulfate hemihydrate (HH) were studied by experiment and molecular dynamics (MD) simulation. It was observed that the additives significantly inhibited the axial growth of HH crystals. The binding energies (Eb) between the additives above and the (0 0 2) face were much higher than the ones of other faces. The following sequence was obtained: Eb(0 0 2) > Eb(1 1 0) > Eb(2 0 0) > Eb(1 −1 0), which could provide a rational interpretation to the experimental results. In addition to the additives above, the effects of other linear alkyl sulfonates (LAS) and alkyl benzene sulfonates (LABS) on the (0 0 2) face were also investigated and the binding energies were increasing with the number of carbon atoms increase. The results obtained from this study should be helpful to the performance evaluation and selection of the morphology modifiers for HH crystals.

The adsorption equilibrium data of CO2 and N2 at (303, 333, 363, 393, 423) K ranging 0-1 bar on zeolite 5A is reported. The pressure and temperature range covers the operating pressure in adsorption units for CO2 capture from power plants. Experimental data were fitted by the multi-site Langmuir model. The adsorbent is much more selective to CO2: loading at 303 K and 100 kPa is 3.38 mol/kg while loading of N2 at the same pressure is 0.22 mol/kg. The Clausius-Clapeyron equation was employed to calculate the isosteric enthalpy of adsorption. The fixed-bed adsorption and desorption of carbon dioxide and nitrogen on zeolite 5A pellets has been studied. A model based on the bi-LDF approximation for the mass transfer, taking into account the energy and momentum balances, had been used to describe the adsorption kinetics of carbon dioxide and nitrogen. The model predicted satisfactorily the breakthrough curves obtained with carbon dioxide–nitrogen mixtures. Desorption process (consisting of depressurization, blowdown, and purge) was also performed. Following the feasibility of concentration and capture of carbon dioxide from flue gases by Pressure Swing Adsorption (PSA) process was simulated. A CO2 recovery of 91.0% with 53.9% purity was obtained using a five-step Skarstrom-type PSA cycle.

A kaolin containing muscovite and quartz (K-SZ) and a pure kaolin (K-SX) with the addition of potassium feldspar, K2SO4 and quartz, respectively, were used to investigate the influences of muscovite and quartz on the formation of mullite from kaolinite in the temperature range 1000–1500 °C. In K-SZ formation of mullite began at 1100 °C, and in K-SX at 1000 °C. In K-SZ quartz accelerated the formation of cristobalite and restrained the reaction of mullite and silica. Muscovite in K-SZ acted as a fluxing agent for silica and mullite before 1400 °C and accelerated the formation of cristobalite. The FTIR band at 896.8 cm− 1 was used to monitor the formation of orthorhombic mullite.

A series of rare earth (Y, Sm and La) doped ceria composite oxides and pure CeO2 were synthesized and evaluated by conducting CH3SH catalytic decomposition test. Several characterization studies, including XRD, BET, Raman, H2-TPR, XPS, FT-IR, CO2-TPD and CH3SH-TPD, were undertaken to correlate structural and surface properties of the obtained ceria-based catalysts with their catalytic performance for CH3SH decomposition. More oxygen vacancies and increased basic sites exhibited in the rare earth doped ceria catalysts. Y doped ceria sample (Ce0.75Y0.25O2-δ), with a moderate increase in basic sites, contained more oxygen vacancies. More structural defects and active sites could be provided, and a relatively small amount of sulfur would accumulate, which resulted in better catalytic performance. The developed catalyst presented good catalytic behavior with stability very similar to that of typical zeolite-based catalysts reported previously. However, La doped ceria catalyst (Ce0.75La0.25O2-δ) with the highest alkalinity was not the most active one. More sulfur species would be adsorbed and a large amount of cerium sulfide species (Ce2S3) would accumulate, which caused deactivation of the catalysts. The combined effect of increased oxygen vacancies and alkalinity led to the catalytic stability of Ce0.75Sm0.25O2-δ sample was comparable to that of pure CeO2 catalyst.

We present a systematic study of the decarboxylation step of the enzyme aspartate decarboxylase with the purpose of assessing the quantum chemical cluster approach for modeling this important class of decarboxylase enzymes. Active site models ranging in size from 27 to 220 atoms are designed, and the barrier and reaction energy of this step are evaluated. To model the enzyme surrounding, homogeneous polarizable medium techniques are used with several dielectric constants. The main conclusion is that when the active site model reaches a certain size, the solvation effects from the surroundings saturate. Similar results have previously been obtained from systematic studies of other classes of enzymes, suggesting that they are of a quite general nature.

Hydrogen production via sorption enhanced steam reforming of ethanol on NiMgAl hybrid materials was studied. A new impregnation method was employed for the preparation of hybrid materials, samples were analyzed on their catalytic properties for steam reforming of ethanol and adsorption capacity to uptake carbon dioxide for sorption enhanced reaction process. The effects of material compositions and operating conditions were analyzed numerically to improve the performance of sorption enhanced reaction process. The simulated sorption enhanced reaction process was then validated experimentally with a good agreement between results obtained from simulations and experiments. A high purity hydrogen stream (>99 mol%) was obtained during the transient period. The use of a CO2 adsorbent can improve the yield of H2 and the thermal efficiency of the H2 production process. Finally, NiMgAl materials showed a good stability during the time-on-stream and cyclic tests due to the unique features of the layered double hydroxide support.

Overuse of antibiotics has become a serious ecological problem worldwide. There is growing concern that antibiotics are losing their effectiveness due to an increased antibiotic resistance in bacteria. During the last twenty years, consumption of antibiotics has increased rapidly in China, which has been cited as one of the world's worst abusers of antibiotics. This review summarizes the current state of antibiotic contamination in China's three major rivers (the Yangtze River, Yellow River, and Pearl River) and illustrates the occurrence and fate of antibiotics in conventional municipal wastewater treatment plants (WWTPs). The analytical data indicate that traditional WWTPs cannot completely remove these concerned pharmaceuticals, as seen in the large difference between the distribution coefficient (Kd) and the uneven removal efficiency of various types of antibiotics. Although constructed wetlands (CWs) offer a potential way to remove these antibiotics from water supplies, knowledge of their mechanisms is limited. There are four main factors affecting the performance of CWs used for the treatment of antibiotics in water supplies, the types and configurations of CWs, hydraulic load rates, substrates, and plants and microorganisms. Further researches focusing on these factors are needed to improve the removal efficiency of antibiotics in CWs.

The crystal structures, elastic, anisotropy, and optical properties of zero-dimension perovskite Cs4BX6 (B = Pb, Sn; X = Cl, Br, I) compounds are investigated by first-principles calculations. The moduli of Cs4BX6 become lower in accordance with the order of Cl, Br, and I, and the moduli of tin-based compounds are larger than lead-based compounds. These two rules apply to other halide perovskites. Besides, Cs4BX6 compounds present obvious mechanical anisotropy and poor ductility. For optical properties, the alignment of PbX6 octahedra dictates the optical transition behavior of perovskite materials and pure Cs4BX6 compounds are candidates for ultraviolet devices due to the large band gaps. For the green emission of Cs4PbBr6, we believe the easily formed CsPbBr3 quantum dots or the defect level from vacancies, dislocations, and interstitial hydroxyl may be the main reason.

Acid leaching residue of coal gasification slag (ALR-CGS) is a by-product of the aluminum extraction process of CGS. Its amount increased with the industrialization of the CGS aluminum extraction process. Thanks to the high silica content of ALR-CGS, this research evaluated the synthesis of MCM-41 using this discarded material. Highly ordered MCM-41 with hexagonal shaped pore diameters of 2.91–3.65 nm was synthesized using ALR-CGS following a non-hydrothermal sol–gel method. The synthesized sample had a BET specific surface area of 1347 m2/g. ALR-CGS is a very competitive alternative silica source in the synthesis of MCM-41.

All-inorganic metal halide perovskites of the formulation ABX₃ (where A is Cs⁺, B is commonly Pb²⁺, and X is a halide, X = Cl, Br, I) have been studied intensively for their unique properties.

The effect of cetyltrimethylammonium bromide (CTAB) on the crystal morphology and size of calcium sulfate whiskers in aqueous HCl solutions was investigated by combined experimental and molecular dynamics (MD) simulation studies. When CTAB was used, calcium sulfate whiskers with small diameters and high aspect ratios were obtained. The MD simulation results indicate that the experimental results can be attributed to the combined effect of the surface adsorption and inhibition of the solute diffusion of CTAB.

In this study, carboxylated magnetic iron oxide nanoparticles (MNPs-COOH) with well-formed nanostructure and magnetic recoverability were prepared successfully via a simple grafting method, and their adsorption competitiveness and differences for different heavy metal ions were generally explored both in single and mixed systems. The results showed that the Cd2+ adsorption demonstrated the strongest resistivity to the effects from exogenous factors with the tightest binding with the carboxyl groups on the MNPs-COOH surface. Besides, the competitive adsorption and multicomponent desorption experiments reflected that the affinity and adsorption priority of the as-synthesized MNPs-COOH for different heavy metal ions were hierarchical and followed the rank of Cd2+ > Cu2+ > Pb2+ > Ni2+, resulting from the disparity of the proportion and intensity of the inner-sphere complexation between heavy metals and the MNPs-COOH. It is hoped that our work could offer effective guidance for the MNPs-COOH application in the wastewater treatments involving various heavy metal contaminants in the future.

Recently, both sand and fly ash have been used for nutrient removal in bioretention systems. However, the improvement in nutrient removal was hampered by a lack of data about of microbial diversity and metabolism effects in the mentioned materials based bioretention systems. Therefore, a mixture with sand, soil and fly ash (1:1:1) was selected as the base in bioretention systems. The investigation of microbial diversity implied that 11 dominant microflora were found, which changed weakly at phylum level but significantly at genus level. The analysis for both urease and extracellular polymer (EPS) showed that urease levels increased with the increase of submerged zone height, which was in line with nitrogen removal, while EPS had the opposite situation. Overall evaluation of microbial role suggested that the enhancement of dominant microflora in the used bioretention systems, like Chloroflexi and Nitrospirae, could strengthen nitrogen removal.

An oxidized biochar was prepared using long-root Eichhornia crassipes through an aerobic/anaerobic hybrid calcination to recycle its waste plants after eutrophic treatments. The adsorption performances of the biochar were investigated and the results showed that the adsorption equilibrium could arrive in 30 min and the adsorption capacities for Pb2+, Cu2+, Cd2+ and Zn2+ at 30 °C were 0.57, 0.41, 0.44 and 0.48 mmol/g, respectively. The adsorption could be promoted at higher pH and temperature and the adsorption tolerance for different heavy metal ions to the existence of competing ions and organic matters was hierarchical. The adsorption was deduced to be heterozygous courses and mainly controlled by complexation of oxygen-containing groups with these heavy metal ions. It was confirmed that the biochar could be regenerated with HCl solution and the adsorption performance kept consistent in 10 adsorption-desorption cycles.

Glutathione (GSH) is the most abundant biological thiol in cells. It can participate in metabolic processes, regulate the body's oxidation level and is essential for various cell functions. An abnormal concentration of glutathione in the cell is directly related to some diseases. Therefore, it is very important to develop fast, sensitive and reversible detection methods for GSH. Herein, we designed a reversible fluorescent probe (named GeP) for sensing GSH based on the nucleophilic addition and dissociation of intracellular GSH to GeP. The probe GeP showed a fast response time and a 20-fold fluorescence change toward GSH. It exhibited excellent mitochondrial-targeted performance and could be used to monitor GSH in mitochondria. Importantly, GeP could also enable superresolution fluorescence imaging of mitochondria through stochastic optical reconstruction microscopy.

The Electro-Fenton process can generate reactive oxygen species capable of oxidizing refractory organic contaminants. However, low regeneration efficiency of Fe2+ restricts its application. Herein, hydroxylamine (HA) was added into the Electro-Fenton (HA/Electro-Fenton) process to accelerate the transformation of Fe3+ to Fe2+. Using dimethyl phthalate (DMP) as target contaminant, the HA/Electro-Fenton system alleviated the two-stage reaction process and accelerated the removal of DMP in the pH range of 2.0–6.0. With improving DMP concentration from 5 mg L-1 to 50 mg L-1, their degradation rate increased in the HA/Electro-Fenton system, while decreased in the Electro-Fenton system. The addition of HA had negligible effect on electro-generation of H2O2, but facilitate the redox cycle of Fe3+/Fe2+ and the generation of hydroxyl radicals, thus improving the degradation of DMP. The final transformation products of HA were N2, N2O, and NO3−. The presence of PO43− improved DMP degradation, while Cl− and organic matters inhibited DMP removal in varying degrees. This study provided useful reference to solve the low efficiency of Fe3+/Fe2+ cycle and expand the pH application range in the Electro-Fenton process.

Lowering the charge barrier is of central importance to develop the advanced lithium-carbon dioxide (Li-CO2) battery with high energy efficiency, yet great challenges remain owing to the sluggish decomposition kinetics of lithium carbonate (Li2CO3) discharge products. Herein, we demonstrate a latent cathode catalyst by strategically constructing the heterointerfaces in hollow NiS2/FeS2 nanostructures dispersed on N, S co-doped graphene aerogel (NiS2/FeS2-NSGA), which displays an exceptional capability to enhance the Li2CO3 decomposition rate, thereby remarkably improving the Li-CO2 battery performance. It has been revealed that the functional heterointerfaces can effectively facilitate the electron transfer and tailor the electronic structure of cathode catalyst, and the hierarchical porous architecture provided by NSGA component favors the mass and electrolyte transportation. Consequently, associated with these synergistic merits, the Li-CO2 battery with NiS2/FeS2-NSGA cathode catalyst delivers a significantly reduced discharge–charge overpotential of 1.10 V at a current density of 0.1 A g−1. Moreover, such battery can be stably cycled over 127 cycles at an increased current density of 1 A g−1 and simultaneously exhibits a superb rate capability. These results highlight the significant role of heterointerface active sites in considerably promoting the Li2CO3 decomposition, opening a new avenue to advance the promising Li-CO2 battery technique.

Driven by winds, the distribution of algae is often noticeably patchy at kilometer scales in shallow lakes. The decomposition of the settled algal biomass may affect nitrogen (N) biogeochemical cycles and thereby N loss in sediments. In this study, we investigated sediment denitrification N-loss patterns along algal migration pathway in Taihu Lake, a shallow and eutrophic lake in China, and found that wind-induced algal migration in the overlying water manipulated the temporal and spatial patterns of denitrification N-loss in sediments. A N loss hotspot in sediments was created in the algae concentrated zone, where N loss was, however, temporarily inhibited during algal bloom seasons and generally exhibited a negative relationship with algal biomass. In the zone where algae have left, sediment N loss rate was relatively low and positively correlated with algal biomass. The decay of algal biomass generated organic carbon and created anoxia, favoring denitrification, while excessive algal biomass could deplete oxygen and inhibit nitrification, causing nitrate limitation for denitrification. Piecewise linear regression analysis indicated that algal biomass of Chl-a > 73.0 μg/L in the overlying water could inhibit denitrification N-loss in sediments. This study adds to our understanding of N biogeochemical cycles in shallow eutrophic lakes.

Highly efficient separation and purification of polyhydroxyalkanoates (PHAs) from PHA-containing cell mass is essential to production of the bioplastics from renewable resources in a cost-effective, environmentally friendly way. Based on selective dissolution of non-PHA cell mass (NPCM) by protons in aqueous solution and crystallization kinetics of PHA biopolymers, a simple process is developed and demonstrated to recover PHAs from cell mass to high purity (>97 wt %) with high yield (>95 wt %). The average molecular weight of biopolyesters is controlled, which follows an exponential function of process severity, a combined factor of processing conditions. Compared with conventional chemical treatment such as sequential surfactant and hypochlorite treatment, this new technology substantially reduces the chemical cost for PHA recovery and purification from PHA-containing cell mass.

Abstract We derived the analytic gradient for the excitation energies from a time-dependent density functional theory calculation within the Tamm–Dancoff approximation (TDDFT/TDA) using Gaussian atomic orbital basis sets, and introduced an efficient serial and parallel implementation. Some timing results are shown from a B3LYP/6-31G**/SG-1-grid calculation on zincporphyrin. We also performed TDDFT/TDA geometry optimizations for low-lying excited states of 20 small molecules, and compared adiabatic excitation energies and optimized geometry parameters to experimental values using the B3LYP and ωB97 functionals. There are only minor differences between TDDFT and TDA optimized excited state geometries and adiabatic excitation energies. Optimized bond lengths are in better agreement with experiment for both functionals than either CC2 or SOS-CIS(D0), while adiabatic excitation energies are in similar or slightly poorer agreement. Optimized bond angles with both functionals are more accurate than CIS values, but less accurate than either CC2 or SOS-CIS(D0) ones. Keywords: excited statestime-dependent density functional theoryanalytical gradientdensity functional theory Acknowledgements YS would like to thank Shawn Brown, Chunmin Chang, Yousung Jung, Anna Krylov, WanZhen Liang, Emil Proynov, Young Min Rhee, Alex Sodt, Ryan Steele, Joe Subotnik and Zhi-Qiang You for helpful discussions. This work was supported, in part, by the Intramural Research Program of NIH, NHLBI. ZG, YS and JK wish to acknowledge the financial support from the National Institutes of Health through SBIR Grant No. GM081928.

A comprehensive off-line two-dimensional liquid chromatography (2D-LC) method coupling normal phase liquid chromatography (NPLC) and reversed phase liquid chromatography (RPLC) was developed for separation and purification of amide alkaloids from Piper longum L. In the first dimension, the crude alkaloid fractions were separated in NPLC mode and 20 fractions were collected. Then fractions 5–20 were selected for further purification in RPLC mode in the second dimension. The purities of RPLC fractions with similar structures were all identified accurately by ultra performance liquid chromatography (UPLC). In total, 28 compounds with high purity were obtained and their structures were comprehensively characterized by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. The results demonstrate that this 2D NPLC × RPLC method with good orthogonality (58.3%) was effective for the preparative separation and purification of amide alkaloids from Piper longum L.

Knowledge of adsorption equilibrium and kinetic data is essential for the design of an adsorption process. In this work, the adsorption equilibrium isotherms of methane and nitrogen are reported at 303, 323, and 343 K over the pressure range from 0 to 700 kPa by a gravimetric system on a carbon molecular sieve (CMS-131510). Methane is preferentially adsorbed. The adsorption capacity at 303 K and 700 kPa is 1.91 mol/kg for methane and 1.01 mol/kg for nitrogen. Experimental data obtained were fitted with the multisite Langmuir model and Toth model. The adsorption kinetics of pure gas was studied by a batch uptake experiment at several different surface coverages within the pressure range of 0–100 kPa and in the same temperature range covered by the equilibrium isotherm. The adsorption rate of both gases is found to be controlled by the surface barrier resistance at the mouth of the micropore and diffusion in the micropore interior. The dual resistance model employed in the simulation can successfully describe the uptake curves. The temperature and concentration dependences of kinetic parameters were also studied. A very high kinetic selectivity was observed. The effect of micropore distribution on the transport parameters is discussed in detail. Binary breakthrough curves were determined, and an enrichment of 50% for methane in the first few seconds was observed. The data reported in this work can be used for the future modeling of adsorption process for the separation of methane and nitrogen on this CMS material.

A new class of 2D fewer-layer π-conjugated conductive metal-organic nanosheets was developed via the Langmuir-Blodgett method, exhibiting ultrahigh mass activity (64.63 A mg-1, 1.7 V vs. RHE) and stability for electrochemical oxygen evolution reactions (OER).

HZSM-5 zeolite catalysts modified with various amounts of Sm were synthesized and evaluated for CH3SH catalytic decomposition tests. The results illustrated that the addition of Sm improved both catalytic activity and stability of the HZSM-5 catalysts. The optimal content of Sm addition was investigated and Sm/HZSM-5 catalyst with 13 wt%-loading demonstrated high stability with no obvious deactivation during the 80 h test, while the pure HZSM-5 catalyst rapidly deactivated after a relatively short time about 15 h on-stream reaction. Based on the characterization results, increased concentration of basic sites were presented on the modified HZSM-5 catalysts. Moreover, the decrease in the amount of strong acid sites over the Sm doped HZSM-5 catalysts significantly suppressed the formation of coke deposit on the catalysts. Acid-base properties of the catalysts were proved to be closely related to the improved catalytic activity and stability.

A series of HZSM-5 zeolite catalysts modified with various rare earth metals (Nd, Er and Y) was prepared and used for CH3SH catalytic decomposition test. The results revealed that addition of rare earth metals significantly improved activity and stability of the HZSM-5 zeolite catalysts, and Nd-modified catalyst exhibited the best performance. Several characterization studies were undertaken to correlate structural and surface properties of the obtained catalysts with their catalytic performance. It was found that acid-base properties of the catalysts were closely related to the catalytic performance. The NH3-TPD and CO2-TPD analysis showed that the concentration of strong acid sites of the HZSM-5 catalysts decreased after rare earth metals addition, while the concentration of basic sites of the catalysts increased. The decrease in the amount of strong acid sites suppressed the formation of coke on the catalysts. The catalysts with increased amount of basic sites displayed better adsorption ability to CH3SH. The UV–vis, 27Al NMR and XRD analysis indicated that the existence of an empty f orbit Nd3+ caused the increase of non-framework aluminium species amount, which leaded to the decrease of the strong acid sites amount. In addition, the optimal loading amount of Nd was investigated and 13wt%Nd/HZSM-5 catalyst showed no obvious deactivation during 60 h test. The spent Nd/HZSM-5 catalyst can be successfully regenerated, showing that Nd/HZSM-5 was an efficient catalyst for CH3SH elimination.

A series of rare earth elements (La, Ce, Pr, Nd, Sm, Y and Er) modified HZSM-5 catalysts were prepared and evaluated their catalytic performance for CH3SH decomposition. XRD, N2 adsorption-desorption, FT-IR, CO2-TPD and NH3-TPD were conducted to analyze the relationships between catalytic behaviors and their structural characteristics. It indicated that addition of rare earth metal could significantly improve activity and stability of HZSM-5 catalyst for CH3SH decomposition, and the best one was La(13)/HZSM-5 sample. CH3SH can be completely converted over La(13)/HZSM-5 at 450 °C compared to parent HZSM-5 at 600 °C. The optimal La(13)/HZSM-5 catalyst exhibited excellent stability without significant deactivation even after 80h time-on-stream test, while parent HZSM-5 was rapidly deactivated within 20 h under same reaction conditions. The excellent performance of La(13)/HZSM-5 can be attributed to its tunable acid-base properties, which not only promote adsorption and activation of CH3SH molecule but also effectively inhibit the formation of coke deposit. In addition, spent La(13)/HZSM-5 catalyst can be easily regenerated and no significant deactivation was observed during regeneration process.

The adsorption and dissociation of H2O2 on the surface of CuO and Ag/CuO have been investigated using density functional theory (DFT). The most stable structure of the small molecules decomposed from H2O2 adsorbed on the surface of CuO and Ag/CuO was determined. The results showed the adsorption energy of H, O, OH, OOH on Ag-doped CuO surface was greater than pure CuO surface. Furthermore, the effect of Ag-doped CuO surface on the decomposition of H2O2 was investigated. We found that the decomposition paths of H2O2 on CuO and Ag/CuO were all through H2O2 → 2OH → H2O + O, but the decomposition of H2O2 on the Ag/CuO surface was achieved easier than on the pure CuO surface. The above data indicated that doping of Ag can indeed make the decomposition of H2O2 on the surface of CuO easier. The present work provides theoretical guidance for improving CuO adsorption capacity in the future.

An all-inorganic cesium lead halide perovskite is particularly attractive as an alternative to next-generation display with high quantum yields and color purity for lasers, light-emitting diode (LED) devices, and single-photon sources. Unfortunately, the vulnerable properties induced by moisture limit the hopeful application of CsPbBr3, especially for high-performance devices. In this work, a monoclinic CsPbBr3 derived from hexagonal Cs4PbBr6 with the assistance of water was presented. Moisture-induced decomposition and phase segregation were recorded at the atomic level in detail. Moreover, the obtained monoclinic CsPbBr3 nanocrystals (NCs) are demonstrated to be decorated with hydroxyl (OH) ligands, which provide a valid approach for the resistance to further moisture attack. The highly stable CsPbBr3 NCs could preserve the photoluminescence intensity above 97% even after the sample was deposited in water for 30 days. Furthermore, a white LED constructed with the as-prepared green-emitting CsPbBr3 and a commercial N628 red phosphor demonstrate the monoclinic CsPbBr3 as a compelling material platform well suited to applications as next-generation light emitters.

Biotic and abiotic pathways for the transformation of phosphorus (P) in the sediment of Taihu Lake, a eutrophic shallow freshwater lake in southeastern China, were studied using the oxygen isotope ratios of phosphate (δ18OP) along with sediment chemistry, X-ray diffraction, and 57Fe-Mössbauer spectroscopic methods. The results showed that δ18OP values of sediment P pools significantly deviated from equilibrium and thus allowed distinguishing potential P sources or pathways of transformation. Isotope values of authigenic P being lighter than equilibrium suggests the re-mineralization of organic matter and subsequent precipitation of apatite as the major pathway of formation of authigenic P. The δ18OP values of the Al-bound P pool (18.9-23.5‰) and ferric Fe-bound P (16.79-19.86‰) could indicate potential terrestrial sources, but the latter being closer to equilibrium values implies partial overprinting of potential source signature, most likely due to reductive dissolution and release of P and followed by partial biological cycling before re-sorption/re-precipitation with newly formed ferric Fe minerals. Oxic/anoxic oscillation and dissolution/re-precipitation reactions and expected isotope excursion are corroborated by sediment chemistry and Mössbauer spectroscopic results. These findings provide improved insights for better understanding the origin and biogeochemical cycling of P associated with eutrophication in shallow freshwater lakes.

Due to energy dissipation, turbulent energy reaching bed sediment greatly differs in lakes with different depths, which potentially affects sediment denitrification and thereby nitrogen loss. In this study, we explored the impacts of turbulent energy reaching sediment on sediment nitrification rate using turbulence simulation experiments, and analyzed its role in determining sediment nitrogen loss in global lakes by investigating the relationship between denitrification rate with lake depth. Results demonstrated that sediment denitrification rate is affected by water depth in lakes with a depth of <~10 m, in which the rate was negatively correlated with lake depth, and maintained stably at low levels of <2.4 mg N m−2 day−1 in lakes with a depth of >~10 m. In shallow lakes, stronger turbulence reaching on sediment yielded higher nitrogen loss rate. Compare with the control, cumulated nitrogen loss from sediment increased by 10% at the turbulent velocity of 4.33 cm s−1 upon sediment. It is possibly because turbulence promoted faster transport of oxygen to surface sediment and enhanced the mineralization of buried organic matters to feed nitrification, which subsequently accelerated denitrification and thereby nitrogen loss. This study can add to our understanding of the role of lake morphology in nitrogen biogeochemical cycles.

The quick coupled reaction of nitric oxide (NO) with superoxide free radicals (·O2−) produces peroxynitrite (ONOO−), it is a powerful biological oxidant. And according to interact with proteins, lipids, nucleic acids and other organisms, the ONOO− eventually leads to all sorts of diseases, for instance, Alzheimer's disease, diabetes, cancer, inflammation. To fully understand the multiple pathological processes of ONOO− in vivo, it is imperative to exploit effective tools to realize the precise, fast and sensitive detection of endogenous ONOO−. We described a novel fluorescent probe named YV in this work, covering the synthesis, characterization and biological application. YV can detect ONOO− by means of fluorescence imaging. Because of the borate group cleavage, YV exhibited a fluorescence intensity change toward ONOO−. It was, the principle of ESIPT that resulted in fluorescence enhancement. The probe YV shows a series of advantages such as high selectivity, fast response, significant Stokes shift and low detection limit. Fluorescence imaging can be used to identify variations in ONOO− in Hela cells and zebrafish. YV will be a robust imaging tool for detecting endogenous ONOO−.

In recent years, novel metal halide scintillators have shown great application potential due to their tunable emission wavelength, high X-ray absorption, and high luminescence efficiency. However, poor stability and complex device packaging remain key issues for metal halide scintillators, making it difficult to achieve high-resolution and flexible X-ray imaging applications. To address the above issues, a multiprocessing strategy was introduced to prepare Cs3Cu2I5@PMMA scintillator films for long-term stable application, mainly undergo different annealing treatments to make Cs3Cu2I5 crystals to accurately nucleate and then grow in-situ in the PMMA matrix. Then, a series of characterization results illustrate that the prepared Cs3Cu2I5@PMMA scintillator films have high crystallinity, uniform size, excellent flexibility, high stable photoluminescence (PL) and radioluminescence (RL) performance, and high-resolution X-ray imaging capability. Most importantly, Cs3Cu2I5@PMMA scintillator films can not only provide clear and accurate imaging recognition of objects with different complex structures but also maintain stable X-ray imaging quality within 60 days and can achieve flexible X-ray imaging. Therefore, we have provided an effective strategy for producing high-quality scintillator films to meet the multidimensional needs of a new generation of scintillators.

One-dimensional Mn1−xCexO2±y nanorod catalysts were synthesized and characterized by X-ray diffraction (XRD) and operando Raman spectroscopy to determine the active phase during methane combustion. Thermal- and reaction-induced phase-transformation determined by operando Raman indicated that the MnOx domain in Mn1−xCexO2±y is the active phase for methane combustion. Besides the peak near 458 cm−1 attributed to F2g mode in CeO2, two new features, corresponding to O vacancies between 590 and 610 cm−1 and Mn3O4-like species (Mn−O−Mn) near 640 cm−1 were observed for Mn1−xCexO2±y nanocrystal catalysts. The number of O vacancies in CeO2 and the surface concentration of MnOx are mainly responsible for methane combustion. Moreover, Mn1−xCexO2±y nanocrystal catalysts show superior activity and stability as compared to α-Mn2O3; especially, Mn0.6Ce0.4O2±y exhibits the highest activity among all samples.

A multifunctional K–Ni–Cu–hydrotalcite hybrid material was synthesized for hydrogen production via sorption-enhanced steam reforming of ethanol. The hydrotalcite material was used as support for the incorporation of nickel and copper, both used as active catalytic phases. This material was studied for its catalytic properties for steam reforming of ethanol; it was found that Cu preferentially catalyzes ethanol dehydrogenation and water–gas shift reactions, while Ni is more suitable for acetaldehyde decomposition and steam reforming of methane. It was found that Ni and Cu formed a Ni0.5Cu0.5 alloy with the advantage of ensemble formation. Also, promising carbon dioxide adsorption capacity of the material was obtained. The potassium promoter together with the hydrotalcite material for carbon dioxide adsorption ensured a successful sorption-enhanced reaction process. High-purity hydrogen stream (99.8 mol % on dry basis) was obtained during the prebreakthrough period at 773 K with a water-to-ethanol molar ratio of 10 in the feed; the concentration of hydrogen then decreased to 67.1 mol % after the breakthrough period.

Sorption enhanced steam reforming of ethanol process for high-purity hydrogen production has been investigated in this work. A two-dimensional mathematical model has been developed to describe the coupled mass and heat transport phenomena within both the axial and radial directions of the adsorptive reactor for sorption enhanced reaction process. The product distribution from the numerical simulation matches well with experimental data obtained from a laboratory-scale fixed-bed adsorptive reactor. In addition, the performance of sorption enhanced reaction is found to be sensitive to the temperature gradient in the radial direction in a scale-up reactor. Afterwards, four reactors with a seven steps cycle operation scheme have been employed in a continuous hydrogen production process. It is found that a hydrogen stream (dry basis) with purity higher than 99 mol %, carbon monoxide content 25 ppm and 0.95 mol kg−1 h−1 productivity of hydrogen can be produced under cyclic steady state operation. The ratio between energy output and input is around 1.7, and the estimated cost of energy is 0.71US$ per kilogram of hydrogen produced. Besides, high purity carbon dioxide (dry basis) can also be captured as a by-product during the sorbent regeneration step in this process.

The 6SA-CASSCF(10, 10)/6-31G (d, p) quantum chemistry method has been applied to perform on-the-fly trajectory surface hopping simulation with global switching algorithm and to explore excited-state intramolecular proton transfer reactions for the o-nitrophenol molecule within low-lying electronic singlet states (S0 and S1) and triplet states (T1 and T2). The decisive photoisomerization mechanisms of o-nitrophenol upon S1 excitation are found by three intersystem crossings and one conical intersection between two triplet states, in which T1 state plays an essential role. The present simulation shows branch ratios and timescales of three key processes via T1 state, non-hydrogen transfer with ratio 48% and timescale 300 fs, the tunneling hydrogen transfer with ratios 36% and timescale 10 ps, and the direct hydrogen transfer with ratios 13% and timescale 40 fs. The present simulated timescales might be close to low limit of the recent experiment results.

Abstract Concerns about the environment and fossil fuel depletion led to the concept of “hydrogen economy”, where hydrogen is used as an energy carrier. Nowadays, hydrogen is mostly produced from fossil fuel resources by natural gas reforming, coal gasification, as well as the water-gas-shift (WGS) reaction involved in these processes. Alternatively, bioethanol, glucose, glycerol, bio-oil, and other renewable biomass-derived feedstocks can also be employed for hydrogen production via steam reforming process. The combination of steam reforming and/or WGS reaction with

Alunite tailings, a secondary resource from copper metallurgy industry in China, are considered a potential resource for both the production of alumina and potash fertilizer, since alunite tailings contain abundant alunite with associated impurities of kaolinite, dickite and quartz. In this work, the direct leaching of alunite from alunite tailings in the highly concentrated KOH solution is proposed. Under appropriate leaching conditions, such as temperature below 90 °C and KOH concentration above 13.5 mol·L− 1, most of alunite is dissolved while kaolinite, dickite and quartz are still remained in the residue. Mastersizer, X-ray diffraction, infrared radiation spectrometer, Raman spectrometer and scanning electron microscopy/energy-dispersive spectroscopy are used to characterize alunite tailings samples before and after leaching. The leaching kinetics of alunite from alunite tailings in the concentrated KOH solution is described using a shrinking core model controlled by the surface chemical reaction. The key kinetics parameters, such as the activated energy and the reaction order, are determined based on the leaching experimental data. The dissolution mechanism of alunite from alunite tailings in the concentrated KOH solution is considered, and is used to account for the reaction order.

In this study, we investigated the exergetic efficiency and thermal energy source of the off-gas system of a submerged arc furnace, which varied from 27% to 35% and 47% to 55%, respectively, of the total energy supply. We used a case study to evaluate the thermal exergy in the off-gas of a real furnace, which exhibited an additional power capacity up to 2.7 MW amounting to 10% of the total energy supplied to the process (or 23% of the electrical power fed to the furnace.) We also determined the perfect negative correlation coefficients (r as the standard) between the exergetic efficiency and raw material consumption via linear regression and observed moderately positive relevance between power consumption and raw material consumption in the furnace. We attributed this correlation to increased graphitization and reduced resistivity of carbonaceous materials as the charging began sink slowly into the reaction zone and the charging temperature increased. Compared to coal, petroleum coke showed a significant impact on total power consumption according to the linear regression results; especially in regards to the fact that petroleum coke underwent graphitization more easily than coal as charging temperature increased.

Spherical mesoporous silica material (SMSM) was hydrothermally synthesized using cetyltrimethylammonium bromide (CTAB) as the template agent and silica fume as the silica source. High-quality SMSMs were successfully prepared by pseudomorphic transformation. The structure and morphology of the SMSMs are investigated by X-ray diffraction, N2 sorption/desorption, Fourier-transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy analyses. The effects of synthetic parameters, such as crystallization time, crystallization temperature, n(NaOH)/n(SiO2) molar ratio, and n(CTAB)/n(SiO2) molar ratio, are quantitatively investigated. The optimal synthetic conditions for high-quality SMSMs are a crystallization time of 48 h, crystallization temperature of 363 K, n(NaOH)/n(SiO2) molar ratio of 0.2–0.3, and n(CTAB)/n(SiO2) molar ratio of 0.15. The qualities of Si–OH are tested by NaOH titration and IR. The results of the both methods confirm that the amount of Si–OH in SMSM is higher than silica fume. Furthermore, SMSMs are employed as effective adsorbents for removing Pb2+ from the static, competitive and column experiments. The capacity for Pb2+ removal demonstrates great improvement.

The typical haze event in Nanjing was selected to study pollution behavior and sulfate formation by field measurement. Based on the concentrations of water soluble inorganic ions in PM2.5, pollution characteristics of the haze were investigated with phase clustering analysis. Besides, δ34S values of SO2 and sulfate in PM2.5 were determined in order to explore sulfur sources and sulfate formation. The result showed that PM2.5 pollution during the haze event was significantly serious, which was mainly from coal combustion, vehicle exhaust emission and biomass burning. Sulfate formation was attributed to aqueous phase sulfur oxidation reactions promoted by high relative humidity and NO2 concentration under the alkaline condition. The color of sky on 22 Dec. was ascribed to the combination of sunset glow and fine particles in high-moisture atmosphere. δ34S values of SO2 are found to be lower than those of sulfate in PM2.5 indicating there was presence of sulfur isotopic fractionation during SO2 oxidation. The average contribution of SO2 homogenous oxidation to sulfate was about 51.2% during the haze events. The ratio of SO2 heterogeneous and homogeneous oxidation to sulfate was mainly attributed to the concentrations of gaseous pollutants (NO2, SO2 and O3) and relative humidity of the atmosphere.

To upgrade efficiently the low-concentration methane gas from nitrogen mixture, CO2 displacement was employed into the traditional vacuum pressure swing adsorption (VPSA) process to form the VPSA-CO2DIS process. Non-isothermal and non-isobaric mathematical model for the VPSA-CO2DIS process was developed, where ternary competitive adsorption equilibrium of CH4, N2 and CO2 was calculated using IAST-Sips formulation, and bi-pore diffusion model was used to describe adsorption kinetics. Experiments were carried out to enrich the low-grade methane gas using one-bed four-step VPSA-CO2DIS process with the home-made granular activated carbons (GACs), and results compared to process simulation predictions. Both experimental and simulated results confirmed that a high purity CH4 product gas (75.40% CH4) could be obtained continuously from 10% CH4 feed gas with 89.02% recovery. The combustion heat of the enriched CH4 product gas was estimated higher than the power consumption of this process, and carbon emissions penalty in this process was evaluated to be activated, so this VPSA-CO2DIS process was technically feasible.

Accurate estimation of reference evapotranspiration (ET0) is a critical prerequisite for the development of agricultural water management strategies. It is challenging to estimate the ET0 of a solar greenhouse because of its unique environmental variations. Based on the idea of ensemble learning, this paper proposed a novel ET0i estimation model named PSO-XGBoost, which took eXtreme Gradient Boosting (XGBoost) as the main regression model and used Particle Swarm Optimization (PSO) algorithm to optimize the parameters of XGBoost. Using the meteorological and soil moisture data during the two-crop planting process as the experimental data, and taking ET0i calculated based on the improved Penman–Monteith equation as the reference truth, the accuracy of model estimation was evaluated and the impact of less input variables on model estimation was tested. The results showed that PSO algorithm could optimize the parameters of XGBoost model stably, PSO-XGBoost model could accurately estimate ET0i in various data modes, and the estimation accuracy of the model decreases with the decrease of the number of input variables. Compared with other integrated learning models, PSO-XGBoost model could obtain the best estimation performance of ET0i.

As microplastic pollution (MP) is currently attracting worldwide attention, the characterisation of microplastics (MPs) in terms of pollution level, sources and migration is of great importance. In the present work, both the Simpson diversity index (SDI) and Shannon-Wiener index (SWI) were used to study the MPs present in the sediments from urban water systems including two lakes (Yushan lake and Nan Lake) and two rivers (Yushan River and Yongfeng River) from Ma'anshan City in the lower reaches of the Yangtze River. The abundance of MPs in sediments ranged between 5 and 153 items·kg−1 with high spatial variation depending on the site. MPs detected in the urban water system were dominated by film (69.8%) in shape, transparent (36.4%) in colour, <1000 μm (50.1%) in size, and Polyethylene (PE, 43.3%) and Polypropylene (PP, 35.5%) in composition. Whilst previous studies have used the diversity of MPs to analyse MP in marine environments, this work aims to obtain the diversity information of MPs in urban areas. The diversity indices of polymer, shape, colour and size were 0–0.685, 0–0.578, 0–0.810 and 0–0.816 for SDI, respectively, and 0–1.255, 0–0.935, 0.1.710 and 0–1.748 for SWI, respectively. Pearson analysis indicates a significant correlation between the number of land-use types and the diversity index of MPs (r = 0.507–0.935, p < 0.05 for SDI; r = 0.528–0.857, p < 0.05 for SWI). Additionally, an attractive fitting relationship between SDI and SWI (p < 0.001) was observed in MP analysis. This means that either of the SDI and SWI can be employed for the analysis of MP. Sites where the urban water system flows into the Yangtze River had a higher abundance of MPs (96 ± 66 items·kg−1) than the urban water system (33 ± 30 items·kg−1) (t = −2.727, p = 0.01), implying that MPs tend to accumulate after they enter the Yangtze River from the urban water system.

Ceria based electrolyte materials have shown potential application in low temperature solid oxide fuel cells (LT-SOFCs). In this paper, Sm3+ and Nd3+ co-doped CeO2 (SNDC) and pure CeO2 are synthesized via glycine-nitrate process (GNP) and the electro-chemical properties of the nanocrystalline structure electrolyte are investigated using complementary techniques. The result shows that Sm3+ and Nd3+ have been successfully doped into CeO2 lattice, and has the same cubic fluorite structure before, and after, doping. Sm3+ and Nd3+ co-doped causes the lattice distortion of CeO2 and generates more oxygen vacancies, which results in high ionic conductivity. The fuel cells with the nanocrystalline structure SNDC and CeO2 electrolytes have exhibited excellent electrochemical performances. At 450, 500 and 550 °C, the fuel cell for SNDC can achieve an extraordinary peak power densities of 406.25, 634.38, and 1070.31 mW·cm−2, which is, on average, about 1.26 times higher than those (309.38, 562.50 and 804.69 mW·cm−2) for pure CeO2 electrolyte. The outstanding performance of SNDC cell is closely related to the high ionic conductivity of SNDC electrolyte. Moreover, the encouraging findings suggest that the SNDC can be as potential candidate in LT-SOFCs application.

It's not clear how fermentation affects the succession and interspecific interaction of functional microorganism in primary sludge anaerobic fermentation system. So as to explore the decisive role of temperature on microorganisms to reveal the mechanism, four fermentation experiments groups (25, 35, 45, and 55 °C) were designed. Results indicated the promotion in proportion of acetic and iso-valeric acid with temperature increasing. High-throughput sequencing reflected that the dominant microbial groups in all samples were Proteobacteria, Firmicutes, Bacteroidetes, Synergetes, Spirochaetae, and then key microbial interspecific interaction changed significantly due to the adjustment of microbial temperature. In addition, amino acid metabolism was the lowest at 35 °C, but carbohydrate metabolism was the highest. The metabolic abundances of amino acids at different temperatures were the highest, but the differences among kind of amino acids were significant. This study could reveal the effect of temperature on VFAs production in terms of microbial interspecific interaction and lay a theoretical foundation for sludge fermentation.

Hypochlorite (ClO−), which is an important reactive oxygen species (ROS) in biology, has attracted scientific attention. Intracellular ClO− are mainly produced in mitochondria. While many studies have shown that ClO− can be detected in mitochondria, low background signal interference fluorescent probes for detecting endogenous ClO− in mitochondria are still lacking. It is crucial to design a fluorescent probe with a large Stocks shift for rapid detection of ClO− in mitochondria in this regard. In this work, we have synthesized the probe PCH that can detect ClO− in the mitochondria. The probe PCH can target mitochondria and has fast response speed, high selectivity, large Stocks shift and low detection limitation. Utilizing this probe, we have been able to detect mitochondrial ClO− endogenously and exogenously. According to our study results, probe PCH can be used as a satisfactory imaging tool for detecting ClO− and can be used as a tool for exploring the complex physiological functions of ClO−.

The potential energy profiles for proton-transfer reactions of 2-hydroxypyridine and its complexes with water were determined by MP2, CASSCF and MR-CI calculations with the 6-31G** basis set. The tautomerization reaction between 2-hydroxypyridine (2HP) and 2-pyridone (2PY) does not take place at room temperature because of a barrier of ∼35 kcal/mol for the ground-state pathway. The water-catalyzed enol−keto tautomerization reactions in the ground state proceed easily through the concerted proton transfer, especially for the two-water complex. The S1 tautomerization between the 2HP and 2PY monomers has a barrier of 18.4 kcal/mol, which is reduced to 5.6 kcal/mol for the one-water complex and 6.4 kcal/mol for the two-water complex. The results reported here predict that the photoinduced tautomerization reaction between the enol and keto forms involves a cyclic transition state having one or two water molecules as a bridge.

The reaction mechanism of the dinuclear zinc enzyme dihydroorotase was investigated by using hybrid density functional theory. This enzyme catalyzes the reversible interconversion of dihydroorotate and carbamoyl aspartate. Two reaction mechanisms in which the important active site residue Asp250 was either protonated or unprotonated were considered. The calculations establish that Asp250 must be unprotonated for the reaction to take place. The bridging hydroxide is shown to be capable of performing nucleophilic attack on the substrate from its bridging position and the role of Zn(beta) is argued to be the stabilization of the tetrahedral intermediate and the transition state leading to it, thereby lowering the barrier for the nucleophilic attack. It is furthermore concluded that the rate-limiting step is the protonation of the amide nitrogen by Asp250 coupled with C-N bond cleavage, which is consistent with previous experimental findings from isotope labeling studies.

Porphyrin is a key cofactor of hemoproteins. The complexes it forms with divalent metal cations such as Fe, Mg, and Mn compose an important category of compounds in biological systems, serving as a reaction center for a number of essential life processes. Employing density functional theory (DFT) and conceptual DFT approaches, the structural properties and reactivity of (pyridine)(n)-M-porphyrin complexes were systematically studied for the following selection of divalent metal cations: Mg, Ca, Cr, Mn, Co, Ni, Cu, Zn, Ru, and Cd with n varying from 0, 1, to 2. Metal selectivity and porphyrin specificity were investigated from the perspective of both structural and reactivity properties. Quantitative structural and reactivity relationships have been discovered between bonding interactions, charge distributions, and DFT chemical reactivity descriptors. These results are beneficial to our understanding of the chemical reactivity and metal cation specificity for heme-containing enzymes and other metalloproteins alike.

Phosphatidylcholine-preferring phospholipase C is a trinuclear zinc-dependent phosphodiesterase, catalyzing the hydrolysis of choline phospholipids. In the present study, density functional theory is used to investigate the reaction mechanism of this enzyme. Two possible mechanistic scenarios were considered with a model of the active site designed on the basis of the high resolution X-ray crystal structure of the native enzyme. The calculations show that a Zn1 and Zn3 bridging hydroxide rather than a Zn1 coordinated water molecule performs the nucleophilic attack on the phosphorus center. Simultaneously, Zn2 activates a water molecule to protonate the leaving group. In the following step, the newly generated Zn2 bound hydroxide makes the reverse attack, resulting in the regeneration of the bridging hydroxide. The first step is calculated to be rate-limiting with a barrier of 17.3 kcal/mol, in good agreement with experimental kinetic studies. The zinc ions are suggested to orient the substrate for nucleophilic attack and provide electrostatic stabilization to the dianionic penta-coordinated trigonal bipyramidal transition states, thereby lowering the barrier.

Perovskite-type SrZrO3 hollow cuboidal nanoshells have been successfully prepared via a simple hydrothermal route from concentrated KOH solutions without any organic or inorganic templates. The products experienced morphology variations of solid microparticles, core–shell particles and hollow nanoshells by alternatively adjusting the base concentration, the reaction temperature and the reaction duration. The hollow cuboidal nanoshells were size tunable by simply adjusting the base concentration. Investigations of the synthetic parameters revealed that the formation of SrZrO3 hollow cuboidal nanoshells was driven by the Ostwald ripening process. Also, the hollow cuboidal nanoshells exhibited defect-induced blue light emission that centered at 468 nm when the samples were exposed to a 324 nm laser.

Ammonium polyphosphate (APP) with crystalline form V (APP-V) was prepared through the reaction of ammonium dihydrogen phosphate and urea at high temperature and under dry ammonia atmosphere. Effects such as raw material ratios, ammoniation, condensation temperature, and condensation time were examined. Its water-solubility was tested and compared with those of industrial APP-I and APP-II. FTIR, XRD, and TGA techniques were used to characterize this product. The thermal degradation of APP-V was examined and compared with that of APP-I and APP-II; the molecular structure of this APP-V was speculated and discussed.

This study investigated the cooling crystallization of aluminum sulfate to explore the basic data for the recovery of aluminum resources from coal spoil. First, the metastable zone width (MSZW) of aluminum sulfate was reported. A parallel synthesis platform (CrystalSCAN) was used to determine the solubility from 10 °C to 70 °C, and an automatic lab reactor (LabMax) equipped with focused beam reflectance measurement (FBRM) was adopted to determine the supersolubility. The effects of operating variables on MSZW were experimentally explored. Results show that the MSZW of aluminum sulfate decreases with increasing stirring speed, while it increases with increasing cooling rate. Second, the continuous crystallization kinetics of aluminum sulfate was investigated in a laboratory-scale mixed-suspension mixed-product removal (MSMPR) crystallizer at a steady state. Growth kinetics presented size-dependent growth rate, which was well fitted with the MJ3 model. Both the growth rate (G) and the total nucleation rate (BTOT) were correlated in the power law kinetic expressions with good correlation coefficients. Third, aluminum sulfate products were modified by sodium dodecylbenzenesulfonate (SDBS). Crystals with large sizes and regular hexagonal plate morphologies were obtained. These crystals reveal that SDBS can inhibit crystal nucleation and promote crystal growth.

Cross-linked Fe(III)-chitosan composite (Fe-CB) was used as the adsorbent for removing perchlorate from the aqueous solution. The adsorption experiments were carried out by varying contact time, initial concentrations, temperatures, pH, and the presence of co-existing anions. The morphology of the adsorbent was discussed using FT-IR and SEM with X-EDS analysis. The pH ranging from 3.0-10.2 exhibited very little effect on the adsorption capability. The perchlorate uptake onto Fe-CB obeyed Langmuir isotherm model. The adsorption process was rapid and the kinetics data obeyed the pseudo second-order model well. The eluent of 2.5% (W/V) NaCl could regenerate the exhausted adsorbent efficiently. The adsorption mechanism was also discussed.

Hydrogen is stored in liquid methanol to ensure safe transportation, and when needed, hydrogen is produced in situ through methanol steam reforming at a relatively low temperature (about 473 K–573 K), which is considered as a significant breakthrough in the storage and transport system of hydrogen energy. To improve methanol conversion, the process intensification technology, called as sorption enhanced methanol steam reforming, is developed, where the configuration between catalyst and sorbent is investigated experimentally in this work. Catalyst is commercial CuO/ZnO/Al2O3 catalyst, and sorbent is K2CO3 promoted hydrotalcite (K-hydrotalcite). Two kinds of packed modes in the reactor are tested and compared with each other, one packed mode with the mixture of catalyst particles and sorbent particles, and the other packed mode with composite sorbent-catalyst particles pelleted with the mixture of catalyst powders and sorbent powders. According to the experimental results, it is found that CO2 adsorption by K-hydrotalcites enhances significantly methanol steam reforming in both packing modes. When combined CuO/ZnO/Al2O3 catalyst with K-hydrotalcite into one-body composite pellet, the methanol conversion reduces due to the loss of catalytic activities under the alkaline atmosphere of K-hydrotalcites. Therefore, attention should be paid on the synergic relationship between catalysts and sorbents for sorption enhanced reaction.

In order to improve the compatibility and dispersion of anhydrous calcium sulfate whiskers (ACSW) in polymer composites, the treatment for surface modification was studied with aqueous solution sodium stearate (SS, C17H35COONa) at hot temperature. The surface modification mechanism between stearate and ACSW was carried out by experimental and density functional theory (DFT) simulation. The surface property of modified anhydrous calcium sulfate whiskers (M-ACSW) became hydrophobic by changing the water contact angle with the calcium sulfate whisker (CSW) from 0° to 132°. The TEM and TG results proved the adsorption of stearate on M-ACSW surface, which was further confirmed by FTIR and XPS. The experimental and DFT simulation outcomes for the mechanism were interpreted by taking the reaction of the carboxyl group of stearate with Ca2+ ions to form calcium stearate on the whisker surface. Their long alkyl chains of stearate coated on the surface of whisker made ACSW improve the surface with a hydrophobic property. Thus, here it is provided details of a novel method of modifier selection for CSW and its interaction mechanism with the crystal surface.

The efficient removal of fluoride from weakly alkaline groundwater still remains a great challenge, owing to the high hydration energy of fluoride. Herein, we conducted in situ precipitation of nanosized hydroxyapatite (nano-HAP) inside a polystyrene anion exchanger D201. The resultant HAP@D201 exhibited almost constant defluoridation efficiency in a wide pH range, especially much higher F– removal efficiency under neutral and weakly alkaline conditions (pH 7–10) than currently available materials. XPS, XRD, and 19F MAS NMR analysis demonstrated that the pH-insensitive defluoridation performance of HAP@D201 was mainly attributed to lattice replacement between the hydroxide ions inside nano-HAP and fluoride in solution, owing to the similar ionic radius of fluoride (1.33 Å) with the hydroxide ion (1.37 Å). The ubiquitous anions like sulfate, chloride, nitrate, and bicarbonate posed negligible effects on the defluoridation performance of HAP@D201, because of the larger ionic radius than for hydroxide ion. Moreover, the HAP@D201 column was capable of successively producing 160, 108, and 92 bed volume (BV) clean water ([F] < 1.5 mg/L) from synthetic water at pH 5.0, 8.0, and 9.0, respectively, 2.5 times more than commercial defluorination material. After adsorption, the exhausted HAP@D201 could be fully refreshed by alkaline solution and retained constant defluoridation efficiency in 10 cyclic column adsorption-regeneration runs.

Deep learning based methods have been widely applied to predict various kinds of molecular properties in the pharmaceutical industry with increasingly more success.

Harmful algal blooms (HABs) have occurred frequently in coastal waters of China, imposing negative effects on the marine ecological environment. A dataset of HABs and terrestrial runoff was collected and analyzed in this study, and factors responsible for HABs were further explored. Frequency and expansion of HABs peaked between 2001 and 2007, and although they have declined slightly since then, they have remained quite high. Frequency and accumulative area of HABs peaked in 2004-2005, and most occurred from April to August during these years. HABs occurred frequently in the Changjiang (Yangtze River) estuary, and Prorocentrum donghaiense, Noctiluca scientillans, Karenia mikimotoi, and Skeletonema costatum were the main algal species. The increases of eutrophication, the abnormal sea surface temperature caused by climate and ocean currents, and the species invasion caused by the discharge of ballast water may be important factors for the long-term outbreak of HABs in the Chinese coastal waters. These findings provide a better understanding of HABs in China, which will be helpful to further prevention and control.

This paper studies the equilibrium structure parameters and the dependences of the elastic properties on pressure for rutile TiO2 by using the Cambridge Serial Total Energy Package (CASTEP) program in the frame of density functional theory. The obtained equilibrium structure parameters, bulk modulus B0 and its pressure derivative B0 are in good agreement with experiments and the theoretical results. The six independent elastic constants of rutile TiO2 under pressure are theoretically investigated for the first time. It is found that, as pressure increases, the elastic constants C11, C33, C66, C12 and C13 increase, the variation of elastic constant C44 is not obvious and the anisotropy will weaken.