Enhanced ozonation of vanillin catalyzed by highly efficient magnetic MnFe2O4/ZIF-67 catalysts: Synergistic effects and mechanism insights.

In this study, we synthesized magnetic MnFe2O4/ZIF-67 composite catalysts using a straightforward method, yielding catalysts that exhibited outstanding performance in catalyzing the ozonation of vanillin. This exceptional catalytic efficiency arose from the synergistic interplay between MnFe2O4 and ZIF-67. Comprehensive characterization via x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and energy dispersive spectroscopy (EDS) confirmed that the incorporation of MnFe2O4 promoted the creation of oxygen vacancies, resulting in an increased presence of l adsorbed oxygen (Oads) and the generation of additional ·OH groups on the catalyst surface. Utilizing ZIF-67 as the carrier markedly enhanced the specific surface area of the catalyst, augmenting the exposure of active sites, thus improving the degradation efficiency and reducing the energy consumption. The effects of different experimental parameters (catalyst type, initial vanillin concentration, ozone dosage, initial pH value, and catalyst dosage) were also investigated, and the optimal experimental parameters (300 mg/L1.0-MnFe2O4/ZIF-67, vanillin concentration = 250 mg/L, O3 concentration = 12 mg/min, pH = 7) were obtained. The vanillin removal efficiency of MnFe2O4/ZIF-67 was increased from 74.95% to 99.54% after 30 min of reaction, and the magnetic separation of MnFe2O4/ZIF-67 was easy to be recycled and stable, and the vanillin removal efficiency of MnFe2O4/ZIF-67 was only decreased by about 8.92% after 5 cycles. Additionally, we delved into the synergistic effects and catalytic mechanism of the catalysts through kinetic fitting, reactive oxygen quenching experiments, and electron transfer analysis. This multifaceted approach provides a comprehensive understanding of the enhanced ozonation process catalyzed by MnFe2O4/ZIF-67 composite catalysts, shedding light on their potential applications in advanced oxidation processes. PRACTITIONER POINTS: A stable and recyclable magnetic composite MnFe2O4/ZIF-67 catalyst was synthesized through a simple method. The synergistic effect and catalytic mechanism of the MnFe2O4/ZIF-67 catalyst were comprehensively analyzed and discussed. A kinetic model for the catalytic ozone oxidation of vanillin was introduced, providing valuable insights into the reaction dynamics.

Electron Redistribution of Ru Site on MoO2@NiMoO4 Support for Efficient Ampere-Level Current Density Electrolysis of Alkaline Seawater.

Seawater electrolysis is a promising but challenging strategy to generate carbon-neutral hydrogen. A grand challenge for hydrogen evolution reaction (HER) from alkaline seawater electrolysis is the development of efficient and stable electrocatalysts to overcome the limitation of sluggish kinetics. Here, a 3D nanorod hybrid catalyst is reported, which comprises heterostructure MoO2@NiMoO4 supported Ru nanoparticles (Ru/ MoO2@NiMoO4) with a size of ≈5 nm. Benefitting from the effect of strongly coupled interaction, Ru/MoO2@NiMoO4 catalyst exhibits a remarkable alkaline seawater hydrogen evolution performance, featured by a low overpotential of 184 mV at a current density of 1.0 A cm-2, superior to commercial Pt/C (338 mV). Experimental observations demonstrate that the heterostructure MoO2@NiMoO4 as an electron-accepting support makes the electron transfer from the Ru nanoparticles to MoO2, and thereby implements the electron redistribution of Ru site. Mechanistic analysis elucidates that the electron redistribution of active Ru site enhances the ability of hydrogen desorption, thereby promoting alkaline seawater HER kinetics and finally leading to a satisfactory catalysis performance at ampere-level current density of alkaline seawater electrolysis.

Selectivity adsorption of sulfate by amino-modified activated carbon during capacitive deionization.

ABSTRACTCapacitive deionization (CDI) is an environmentally friendly desalination technique with low energy consumption. However, unmodified carbon electrode materials have poor sulfate selectivity and adsorption capacity. In this work, to improve sulfate selectivity, we prepared activated carbon materials loaded with different amino contents by grafting amino groups via acid treatment for different times. In the competitive ion adsorption experiments, the sulfate selectivity of AC was only 0.64 and the amino-modified AC increased by 1.98-2.52 times due to the formation of stronger hydrogen bonds between the amino group and sulfate. AC-NH2-4 had the best selectivity and the sulfate selective coefficient was 2.25. The desorption of sulfate was 92.46% within one hour. In addition, the surface of the amino-modified activated carbon showed significantly improved electrochemical properties and better capacitance. The specific capacitance of amino-modified AC in different electrolyte solutions was consistent with the competitive adsorption results. The specific capacitance of amino-modified AC in Na2SO4 electrolyte solution was the highest. The modified electrode material also had the advantages of a higher adsorption capacity and excellent regeneration performance after continuous electric adsorption-desorption cycles. Therefore, it may have development potential to selectively adsorb sulfate in practical applications.

Synergistic mechanism of supported Mn-Ce oxide in catalytic ozonation of nitrofurazone wastewater.

In this study, the catalytic materials of MnOx/γ-Al2O3, CeO2/γ-Al2O3, and MnxCe1-xO2/γ-Al2O3 for catalytic ozonation were synthesized. The catalysts were used in heterogeneous catalytic ozonation of the wastewater containing ntrofurazone (NFZ). The effects of the catalytic ozonation operational factors were systematically evaluated in terms of ozone dosing, catalyst dosing, initial NFZ concentration, and pH. The results showed that the catalytic activity of the MnxCe1-xO2/γ-Al2O3 was higher than that of the MnOx/γ-Al2O3 and CeO2/γ-Al2O3. The kinetics analysis revealed that bimetallic loading has a synergistic effect and the mechanism of this effect was investigated in the catalytic ozonation system. The catalysts were characterized by FESEM, EDS, XRD, XPS, IR, and BET. The characteristics of the catalysts revealed that Mn could alter the oxide species on the metal surface and interfere with the formation of CeO2 crystals, which led to smaller grains, enhanced adsorption oxygen, and greater specific surface area. The MnxCe1-xO2/γ-Al2O3 crystals could form a solid solution, which helps higher catalytic activity. This study adds to the understanding of the synergistic mechanism of the loaded Ce-Mn oxide catalysts in the heterogeneous catalytic ozonation system and provides a feasible method for degrading pharmaceutical wastewater.

Metabonomic and transcriptomic modulations of HepG2 cells induced by the CuO-catalyzed formation of disinfection byproducts from biofilm extracellular polymeric substances in copper pipes.

Cupric oxide (CuO) is able to catalyze the reactions among disinfectant, extracellular polymeric substances (EPS) and bromide (Br-) in copper pipes, which may deteriorate the water quality. This study aimed to investigate the metabonomic and transcriptomic modulations of HepG2 cells caused by the CuO-catalyzed formation of disinfection byproducts (DBPs) from EPS. The presence of CuO favored the substitution reactions of chlorine and bromine with EPS, inducing a higher content of total organic halogen (TOX). In addition, DBPs were shifted from chlorinated species to brominated species. A total of 182 differential metabolites (DMs) and 437 differentially expressed genes (DEGs) were identified, which were jointly involved in 38 KEGG pathways. Topology analysis indicates that glycerophospholipid and purine metabolism were disturbed most obviously. During glycerophospholipid metabolism, the differential expression of genes GPATs, AGPATs, LPINs and DGKs impacted the conversion of glycerol-3-phosphate to 2-diacyl-sn-glycerol, which further affected the conversion among phosphatidylcholine, phosphatidylserine and phosphocholines. During purine metabolism, it was mainly the differential expression of genes POLRs, RPAs, RPBs, RPCs, ENTPDs and CDs that impacted the transformation of RNA into guanine-, xanthosine-, inosine- and adenosine monophosphate, which were further successively transformed into their corresponding nucleosides and purines. The study provides an omics perspective to assess the potential adverse effects of overall DBPs formed in copper pipes on human.

Electrochemical oxidation of sulfamethoxazole by nitrogen-doped carbon nanosheets composite PbO2 electrode: Kinetics and mechanism.

In this study, nitrogen-doped carbon nanosheets (NCNSs) were prepared and successfully combined into the PbO2 electrode by the composite electrodeposition technology, thereby NCNS-PbO2 electrode was obtained. The electrochemical degradation of sulfamethoxazole (SMX) in aqueous solution by NCNS-PbO2 electrode was studied. The main influence factors on the degradation of SMX, such as the initial concentration of SMX, current density, electrolyte concentration and initial pH value, were analyzed in detail. Under the optimal process conditions, after 120 min of treatment, the removal ratio of SMX and chemical oxygen demand (COD) reached 99.8 % and 60.7 %, respectively. The results showed that the electrochemical degradation of SMX fitted pseudo-first-order reaction kinetics. The electrochemical performance of NCNS-PbO2 electrode was better than that of PbO2 electrode by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, as well as the use of cyclic voltammetry and electrochemical impedance spectroscopy for electrochemical performance testing. This was because the doping of nitrogen atoms improved the properties of carbon nanosheets. After the composite, the active sites on the surface of PbO2 were improved, the particle size of PbO2 was reduced, and the electrical conductivity and electrocatalytic activity of the electrode were improved. In addition, the intermediate products were determined by GC-MS method, and the possible degradation pathways of SMX were proposed.

Mechanism of catalytic ozonation for elimination of methyldopa with Fe3 O4 @SiO2 @CeO2 catalyst.

In this study, a magnetic nanocatalyst (Fe3 O4 @SiO2 @CeO2 ) was prepared and applied in the catalytic ozonation of methyldopa (MD). The effects of operational parameters on catalytic ozonation performance were investigated, including ozone dosage, catalyst dosage, initial MD concentration, and pH. The removal of MD was 45.2% in ozonation, whereas the efficiency was achieved to 83.0% with the addition of Fe3 O4 @SiO2 @CeO2 . The results showed that Fe3 O4 @SiO2 @CeO2 could significantly improve the catalytic ozonation performance. And the enhanced mechanism study showed that it was attributed to promotion of ozone decomposition to generate hydroxyl radical. The reaction model was explored, and the reaction rates were calculated for the MD degradation in catalytic ozonation. A higher degradation efficiency of MD in catalytic ozonation was attributed to the enhanced surface effect of the catalysts, which was confirmed by using TBA, PO4 3- , and p-BQ as scavengers of hydroxyl radical, surface reaction, and superoxide radical. The hydroxyl radical and superoxide radical played an important role in the degradation of MD. The mechanism of catalytic ozonation by Fe3 O4 @SiO2 @CeO2 was discussed via X-ray photoelectron spectroscopy (XPS) spectra and experimental data.

Fabrication of a multi-layer CNT-PbO2 anode for the degradation of isoniazid: Kinetics and mechanism.

In this study, the CNTs were successfully compounded in PbO2 electrode through composite electrodeposition technology to obtain multi-layer CNT-PbO2 electrode. Scanning electron microscope, X-ray diffraction and X-ray Photoelectron Spectroscopy were comprehensively used to characterize the lead dioxide electrode and the electrochemical performance were also tested by cyclic voltammetry, and electrochemical impedance spectroscopy. Results showed that CNT-PbO2 significantly improved the electrochemical performance, which was attributed to that the compound of CNTs in PbO2 improved the active sites on the surface, with higher oxidation peaks, smaller particle size, larger specific surface area, and lower charge transfer resistance. In the degradation experiment, the chemical oxygen demand removal efficiency of isoniazid by CNT-PbO2 electrode were 1.37 times of that by pure PbO2 electrode. The main influence factors on the degradation of ISN, such as initial ISN concentration, Na2SO4 concentration, current density and initial pH value was analyzed in detail. Considered comprehensively the effects of ISN removal efficiency, COD and average current efficiency, the degradation of ISN and COD reached 99.4% and 86.8%, respectively, after the electrode was degraded by electrochemical oxidation for 120 min under the best conditions. In addition, the degradation mechanism of ISN in electrochemical oxidation was studied. According to the intermediate products detected by GC-MS, the possible degradation pathway of ISN in electrochemical oxidation system were proposed.

Enhanced BiFeO3/Bi2Fe4O9/H2O2 heterogeneous system for sulfamethoxazole decontamination: System optimization and degradation pathways.

Sulfonamides as the major antibiotic have become emerging contaminants worldwide in aquatic environments. Herein, a heterogeneous Fenton-like oxidation driven by a novel BF-PMCs bismuth ferrites reported firstly for efficient degradation of sulfamethoxazole (SMX) in which the possible degradation pathways are thoroughly analyzed through identifying some of key intermediates (i.e., C8H11N3O4S, C4H4NO2, etc.) using liquid chromatography-mass spectrum (LC-MS), monitoring organic acids (i.e., acetic acid, pyruvic acid) and inorganic anions (i.e., sulfate, nitrate) using ion chromatography (IC), and detecting radical species (i.e., HO) using both chemical quenchers and fluorescence technique, simultaneously. The optimal operations in BF-PMCs/H2O2 system for SMX degradation are recommended at the conditions of initial pH ~4.5, 1.5 mg L-1 [SMX], 70 mM [H2O2], and BF-PMCs loading of 0.2 g L-1. The degradation rates (kinetic value of kapp) for SMX, azoxystrobin, bisphenol A, and 2,4-dichlorophenol are 9.5 × 10-3, 13.6 × 10-3, 7.3 × 10-3, and 5.9 × 10-3 min-1, respectively. Meanwhile, the degradation rates in BF-PMCs/H2O2 system for SMX degradation are slightly slower in the presence of inorganic anions (e.g., Cl-, NO3-) and NOM (e.g., humic acid). Based on an overall consideration, the BF-PMCs/H2O2 system has great potential for degradation of emerging organic pollutants (EOPs) in natural water systems.

Electrochemical oxidation of Acid Orange 7 azo dye using a PbO2 electrode: Parameter optimization, reaction mechanism and toxicity evaluation.

In this study, electrochemical oxidation of Acid Orange 7 (AO 7) azo dye has been investigated using a Fe-doped PbO2 electrode. The degradation of AO 7 followed pseudo-first-order reaction kinetics. The removals of AO 7, chemical oxygen demand (COD) and total organic carbon (TOC) were 87.15%, 49.88% and 44.94% after 60 min of electrolysis at the optimal conditions (Na2SO4 concentration 0.1 M, initial pH 5, initial AO 7 concentration 100 mg L-1 and applied current density 20 mA cm-2), respectively. And the corresponding degradation rate constant was 0.035 min-1. The intermediates formed during electrochemical process were identified, and a possible degradation pathway was proposed, which was initiated by the oxidation of azo bond (-NN-), hydroxylation and substitution reaction of -NH2 and -SO3H under the attack of OH, and ended with the formation of mineralization products such as NH4+, NO3-, SO42-, CO2 and H2O. The toxicity of treated AO 7 solution towards Vibrio fischeri increased slightly at first and then rapidly reduced to non-toxicity with prolonging time. The results indicate that electrochemical oxidation of AO 7 using Fe-doped PbO2 electrode is a promising way.

Strongly Coupled 3D N-Doped MoO2/Ni3S2 Hybrid for High Current Density Hydrogen Evolution Electrocatalysis and Biomass Upgrading.

Developing noble metal-free electrocatalysts toward hydrogen evolution reaction (HER) that can work well at ultrahigh current density are crucial components in renewable energy technologies. Herein, we have reported a strongly coupled 3D hybrid electrocatalyst, which consists of N-doped MoO2 with Ni3S2 grown on Ni foam (N-MoO2/Ni3S2 NF) through an annealing treatment, followed by a thermal ammonia reaction. This N-MoO2/Ni3S2 with a particle size of ∼50 nm was evenly grown on the Ni substrate in this 3D hybrid system. Benefiting from the strong coupling effect, the N-MoO2/Ni3S2 NF exhibited a high HER performance in basic media, with a small value of the Tafel slope (76 mV dec-1) and a low potential of 517 mV at 1000 mA cm-2, which was superior to that of Pt/C (631 mV at 1000 mA cm-2). Experimental results revealed that constructing a coupling interface between N-MoO2 and Ni3S2 facilitated the absorption and dissociation of water molecules, consequently boosting the HER activity. Additionally, the 3D N-MoO2/Ni3S2 NF hybrid could act as a bifunctional electrode for both anode (biomass upgrading) and cathode (HER), which only required a lower potential of 2.08 V at 100 mA cm-2 as compared to the overall water splitting (2.25 V) and achieved a high biomass conversion ratio of over 90%. Moreover, substituting oxygen evolution reaction by urea oxidation reaction also can assist energy-saving hydrogen evolution for 3D N-MoO2/Ni3S2 NF.

Electrochemical removal of amoxicillin using a Cu doped PbO2 electrode: Electrode characterization, operational parameters optimization and degradation mechanism.

This work investigated the electrochemical degradation of amoxicillin (AMX) in aqueous solution with Cu-PbO2 electrode. The main influence factors on the degradation of AMX, such as Na2SO4 concentration, initial AMX concentration, current density and initial pH value, were analyzed in detail. Under the optimal conditions, the removal rates of AMX and chemical oxygen demand (COD) reached 99.4% and 46.3% after 150 min treatment. The results indicated that the electrochemical degradation of AMX fitted pseudo-first-order reaction kinetics. Compared with undoped PbO2 electrode, Cu-PbO2 electrode had a smaller crystal size, more proportion of hydroxyl oxygen species, greater AMX and chemical oxygen demand (COD) removal efficiency, higher average current efficiency (ACE) and lower electrical efficiency per log order (EE/O). Electrochemical oxidation using Cu-PbO2 electrodes was an effective way to eliminate amoxicillin in aqueous solution. Moreover, a possible degradation pathway including ring open and mineralization was proposed by intermediate products determined by GC-MS method. This paper could provide basic data and technique reference for the amoxicillin wastewater pollution control.

Sulfide and arsenic compounds removal from liquid digestate by ferric coagulation and toxicity evaluation.

The liquid digestate has been regarded as a potential organic fertilizer for its benefit in nutrients recovery. However, the potential risk of hazardous substances remaining in the wastewater was still one of the main obstacles for the wastewater application in the circular agriculture. The pretreatment is important to remove pollutants with relatively satisfied results. Ferric coagulation was a feasible way to simultaneously remove various contaminants in the wastewater with few residuals of ferric ions under alkaline and neutral conditions. In special, it could reduce the residues of sulfide and arsenic compounds. We gained insights into the mechanism of ferric coagulation in removing sulfide and arsenic compounds. Redox reaction and precipitation were the reasons resulting in removing sulfide. The formation of precipitate by combining with iron(III) contributes to the removal of arsenic compounds. Toxicity tests using Scenedesmus obliquus and Chlorella pyrenoidosa showed an obvious reduction of toxicity for the liquid digestate after ferric coagulation. Besides, ferric coagulation could efficiently remove turbidity, reduce COD, and eliminate dissolved organic matters correlated with the fate of heavy metal and antibiotics. Therefore, this paper could give basic data and technique supports for the secure utilization and pollution control of liquid digestate. PRACTITIONER POINTS: Most sulfide and arsenic compounds were removed by 0.01 M ferric coagulation. Mechanisms on removing hazardous substances by ferric coagulation were discussed based on analysis of X-ray photoelectron spectroscopy and FTIR. The evaluation by two algae showed the toxicity of liquid digestate could be reduced obviously after ferric coagulation.

Study of biogas slurry concentrated by reverse osmosis system: characteristics, optimization, and mechanism.

Biogas slurry, also called liquid digestate, refers to the liquid part of the anaerobic digestate produced from the anaerobic digestion process, which is an environmental pollution source if it is discharged without proper treatment. To recover the nutrients in the biogas slurry, a membrane system was designed to concentrate in the work. The effects of pretreatment technology including gravity settling and ultrafiltration process were studied via analyzing the chemical oxygen demand (COD), ammonia nitrogen (NH3 -N), total nitrogen (TN), and conductivity. Reverse osmosis was applied in the biogas slurry concentration. The performance of reverse osmosis membrane used in the concentration process was studied by analyzing the permeate and concentrate (retentate), the volume reduction factor, and the concentration factor. The suitable parameters were selected as 20.0-25.0°C for influent temperature, 0.8-1.0Mpa for operating pressure, and 6.0-8.0 for influent pH. Furthermore, the feasible concentration factor was evaluated as 4. The economic, environmental, and social benefits could be gained if (concentrated) biogas slurry was used as an alternative to chemical fertilizers. PRACTITIONER POINTS: Reverse osmosis system was established for biogas slurry concentrating. The operational factors were optimized on biogas slurry concentrating and separation. The biogas slurry separation mechanism was discussed.

Long-term exposure to the non-steroidal anti-inflammatory drug (NSAID) naproxen causes thyroid disruption in zebrafish at environmentally relevant concentrations.

The presence of trace levels of pharmaceuticals is an emerging issue impacting the aquatic ecosystem. Naproxen (NPX) is a nonsteroidal anti-inflammatory drug (NSAID) that has been frequently detected in aquatic environments worldwide. Recently, concerns regarding endocrine disruption by NSAIDs have increased; however, their effects on the thyroid system have yet to be understood. In this study, zebrafish were utilized to evaluate the thyroid-disrupting effects of NPX. After a 60-day exposure to various concentrations of NPX (0.1, 1, 10 and 100 µg/L), the body length and weight of the zebrafish were significantly decreased. The decrease of cytochrome P450 gene expression and enzyme activity might inhibit the metabolism of NPX, which might result in the significant bioconcentration in zebrafish. Thyroid hormone (TH) analysis showed that both triiodothyronine (T3) and thyroxine (T4) levels were substantially decreased. Gene transcription expressions along the hypothalamic-pituitary-thyroid (HPT) axis were also markedly affected. Significant downregulation of dio1, dio2, nis, nkx2.1, pax8, tg, tpo, trß and ttr levels, along with the stimulation of the tshß gene, were also observed in exposed fish compared to controls. Western blot analysis indicated that expression of the TTR protein was significantly decreased, which coincides with the results of the gene expression analysis. Collectively, our observations show that NPX increases the risk of bioconcentration and thyroid disruption in zebrafish. Given the continued increasing consumption and emission of pharmaceuticals, thyroid disruption should be considered when assessing the aquatic risk of long-term exposure to environmentally relevant concentrations of pharmaceuticals.

Catalytic Ozonation for the Degradation of 5-Sulfosalicylic Acid with Spinel-Type ZnAl2O4 Prepared by Hydrothermal, Sol-Gel, and Coprecipitation Methods: A Comparison Study.

This study presents a novel spinel-type zinc aluminate nanometer catalyst and is applied in catalytic ozonation for wastewater treatment. The zinc aluminate (ZnAl2O4) catalysts were synthesized by hydrothermal, sol-gel, and coprecipitation methods, and their characteristics were analyzed by X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectrum, Fourier transform infrared, and X-ray photoelectron spectroscopy (XPS) techniques. 5-Sulfosalicylic acid (SSal) was selected as the typical pharmaceutical and personal care product and used to evaluate the catalytic activity of ZnAl2O4. Compared to ozonation, an obviously higher removal efficiency for the SSal degradation was achieved with the nanocatalyst addition in catalytic ozonation. The removal of SSal and chemical oxygen demand reached 64.8 and 46.2%, respectively, after 60 min in the presence of ZnAl2O4, whereas it was only 49.4 and 33.2%, respectively, in ozonation. The comparison of catalysts showed that the ZnAl2O4 prepared by the hydrothermal method presented a better catalytic activity in ozonation. The effect of radical scavenger experiment results and the characterization of XPS implied that •OH was the main active oxidative species in catalytic ozonation. The reusability results showed that the ZnAl2O4 catalyst possessed a high stability and could be widely used in catalytic ozonation for wastewater treatment.

Electrochemical degradation of antibiotic levofloxacin by PbO2 electrode: Kinetics, energy demands and reaction pathways.

In this work, the electrochemical degradation of antibiotic levofloxacin (LFX) has been studied using a novel rare earth La, Y co-doped PbO2 electrode. The effect of applied current density, pH value and initial LFX concentration on the degradation performance were systematically evaluated. The results demonstrated that electrochemical oxidation of LFX over the La-Y-PbO2 electrode was highly effective and the reaction followed an apparent first-order kinetic model. Considering the degradation efficiency and energy efficiency, the relative optimal conditions are identified as current density 30 mA cm-2, pH 3 and initial LFX concentration 800 mg L-1. According to the identified products, a reaction mechanism has been proposed and the products were further oxidized to CO2, H2O, NH4+, NO3- and F-. A total of four aromatic intermediate products of LFX degradation were identified and the different structural changes to the LFX molecule included pepiperazinyl hydroxylation, decarboxylation and defluorination.

Biocatalysis mechanism for p-fluoronitrobenzene degradation in the thermophilic bioelectrocatalysis system: Sequential combination of reduction and oxidation.

To verify the potentially synthetic anodic and cathodic biocatalysis mechanism in bioelectrocatalysis systems (BECSs), a single-chamber thermophilic bioelectrocatalysis system (R3) was operated under strictly anaerobic conditions using the biocathode donated dual-chamber (R1) and bioanode donated dual-chamber (R2) BECSs as controls. Direct bioelectrocatalytic oxidation was found to be infeasible while bioelectrocatalytic reduction was the dominant process for p-Fluoronitrobenzene (p-FNB) removal, with p-FNB removal of 0.188 mM d(-1) in R1 and 0.182 mM d(-1) in R3. Cyclic voltammetry experiments confirmed that defluorination in the BECSs was an oxidative metabolic process catalyzed by bioanodes following the reductive reaction, which explained the 0.034 mM d(-1) defluorination in R3, but negligible defluorination in controls. Taken together, these results revealed a sequentially combined reduction and oxidation mechanism in the thermophilic BECS for p-FNB removal. Moreover, the enrichment of Betaproteobacteria and uniquely selected Bacilli in R3 were probably functional populations for p-FNB degradation.

A review of polychlorinated biphenyls (PCBs) pollution in indoor air environment.

UNLABELLED: Polychlorinated biphenyls (PCBs) were widely used in industrial production due to the unique physical and chemical properties. As a kind of persistent organic pollutants, the PCBs would lead to environment pollution and cause serious problems for human health. Thus, they have been banned since the 1980s due to the environment pollution in the past years. Indoor air is the most direct and important environment medium to human beings; thus, the PCBs pollution research in indoor air is important for the protection of human health. This paper introduces the industrial application and potential harm of PCBs, summarizes the sampling, extracting, and analytical methods of environment monitoring, and compares the indoor air levels of urban areas with those of industrial areas in different countries according to various reports. This paper can provide a basic summary for PCBs pollution control in the indoor air environment. IMPLICATIONS: The review of PCBs pollution in indoor air in China is still limited. In this paper, we introduce the industrial application and potential harm of PCBs, summarize the sampling, extracting, and analytical methods of environment monitoring, and compare the indoor air levels of urban areas with industrial areas in different countries according to various reports.

Insight into deactivation of commercial SCR catalyst by arsenic: an experiment and DFT study.

Fresh and arsenic-poisoned V2O5­WO3/TiO2 catalysts are investigated by experiments and DFT calculations for SCR activity and the deactivation mechanism. Poisoned catalyst (1.40% of arsenic) presents lower NO conversion and more N2O formation than fresh. Stream (5%) could further decrease the activity of poisoned catalyst above 350 °C. The deactivation is not attributed to the loss of surface area or phase transformation of TiO2 at a certain arsenic content, but due to the coverage of the V2O5 cluster and the decrease in the surface acidity: the number of Lewis acid sites and the stability of Brønsted acid sites. Large amounts of surface hydroxyl induced by H2O molecules provide more unreactive As­OH groups and give rise to a further decrease in the SCR activity. N2O is mainly from NH3 unselective oxidation at high temperatures since the reducibility of catalysts and the number of surface-active oxygens are improved by As2O5. Finally, the reaction pathway seems unchanged after poisoning: NH3 adsorbed on both Lewis and Brønsted acid sites is reactive.