Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirme...Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer(DET),Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production.The results of this study indicated that the potential DET participator,Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer,then transferred electrons directly to the definite DET participators,Methanosarcina/Methanothrix via microbemicrobe electrons transfer for CH_(4)production.In addition,Methanobacterium is another specially enriched methanogen on Fe(0)-cathode,which might obtain electrons directly from Fe(0)-cathode to produce CH_(4) via metal/electrode-microbe DET.The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester(R1)further confirmed the enrichment of electroactive microorganisms participating in DET process.As a consequence,a higher CH_(4) production(1205–1508 m L/d)and chemical oxygen demand(COD)removal(79.0%-93.8%)were achieved in R1 compared with graphite-cathode MES digester(R2,720–1090 m L/d and 63.6%-85.6%)and the conventional anaerobic digester(R3,384–428 m L/d and 35.2%-41.0%).In addition,energy efficiency calculated indicated that the output energy of CH_(4) production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.展开更多
Magnetic Cu^0/Fe3O4 submicron composites were prepared using a hydrothermal method and used as heterogeneous catalysts for the activation of peroxymonosulfate（PMS） and the degradation of organic pollutants.The as-pr...Magnetic Cu^0/Fe3O4 submicron composites were prepared using a hydrothermal method and used as heterogeneous catalysts for the activation of peroxymonosulfate（PMS） and the degradation of organic pollutants.The as-prepared magnetic Cu^0/Fe3O4 submicron composites were composed of Cu^0 and Fe3O4 crystals and had an average size of approximately 220 nm.The Cu^0/Fe3O4 composites could efficiently catalyze the activation of PMS to generate singlet oxygen,and thus induced the rapid degradation of rhodamine B,methylene blue,orange Ⅱ,phenol and 4-chlorophenol.The use of0.1 g/L of the Cu^0/Fe3O4 composites induced the complete removal of rhodamine B（20 μmol/L） in15 min,methylene blue（20 μmol/L） in 5 min,orange Ⅱ（20 μmol/L） in 10 min,phenol（0.1mmol/L） in 30 min and 4-chlorophenol（0.1 mmol/L） in 15 min with an initial pH value of 7.0 and a PMS concentration of 0.5 mmol/L.The total organic carbon（TOC） removal higher than 85%for all of these five pollutants was obtained in 30 min when the PMS concentration was 2.5 mmol/L.The rate of degradation was considerably higher than that obtained with Cu^0 or Fe3O4 particles alone.The enhanced catalytic activity of the Cu^0/Fe3O4 composites in the activation of PMS was attributed to the synergistic effect of the Cu^0 and Fe3O4 crystals in the composites.Singlet oxygen was identified as the primary reactive oxygen species responsible for pollutant degradation by electron spin resonance and radical quenching experiments.A possible mechanism for the activation of PMS by Cu^0/Fe3O4 composites is proposed as electron transfer from the organic pollutants to PMS induces the activation of PMS to generate ^1O2,which induces the degradation of the organic pollutants.As a magnetic catalyst,the Cu^0/Fe3O4 composites were easily recovered by magnetic separation,and exhibited excellent stability over five successive degradation cycles.The present study provides a facile and green heterogeneous catalysis method for the oxidative removal of organic pollutants.展开更多
零价铁渗透式反应墙技术(zero-valent iron permeable reactive barrier,Fe^0-PRB)是近年来兴起的一项高效经济的地下水原位修复技术,被成功应用于地下水Cr(Ⅵ)污染的场地修复中.针对Fe^0-PRB去除Cr(Ⅵ)的反应影响机制开展研究,从动力...零价铁渗透式反应墙技术(zero-valent iron permeable reactive barrier,Fe^0-PRB)是近年来兴起的一项高效经济的地下水原位修复技术,被成功应用于地下水Cr(Ⅵ)污染的场地修复中.针对Fe^0-PRB去除Cr(Ⅵ)的反应影响机制开展研究,从动力学角度揭示零价铁去除Cr(Ⅵ)的环境条件响应规律,获得描述零价铁去除Cr(Ⅵ)的反应动力学模型.考察了地下水常见离子对Cr(Ⅵ)去除的影响,发现地下水中氯离子通过影响电子传递影响Cr(Ⅵ)去除,硫酸根、镁离子通过参与反应影响Cr(Ⅵ)去除,碳酸氢根通过参与反应和影响电子传递共同影响Cr(Ⅵ)去除,钙离子对Cr(Ⅵ)去除影响不大.研究结果为Fe^0-PRB去除Cr(Ⅵ)的工艺参数优化提供方法和理论依据.展开更多
基金the financial support from the National Natural Scientific Foundation of China(No.52000020)the National Natural Scientific Foundation of China(No.21876022)。
文摘Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer(DET),Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production.The results of this study indicated that the potential DET participator,Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer,then transferred electrons directly to the definite DET participators,Methanosarcina/Methanothrix via microbemicrobe electrons transfer for CH_(4)production.In addition,Methanobacterium is another specially enriched methanogen on Fe(0)-cathode,which might obtain electrons directly from Fe(0)-cathode to produce CH_(4) via metal/electrode-microbe DET.The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester(R1)further confirmed the enrichment of electroactive microorganisms participating in DET process.As a consequence,a higher CH_(4) production(1205–1508 m L/d)and chemical oxygen demand(COD)removal(79.0%-93.8%)were achieved in R1 compared with graphite-cathode MES digester(R2,720–1090 m L/d and 63.6%-85.6%)and the conventional anaerobic digester(R3,384–428 m L/d and 35.2%-41.0%).In addition,energy efficiency calculated indicated that the output energy of CH_(4) production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.
基金supported by the National Natural Science Foundation of China (21377169, 21507168)the Fundamental Research Funds for the Central Universities (CZW15078)the Natural Science Foundation of Hubei Province of China (2014CFC1119, 2015CFB505)~~
文摘Magnetic Cu^0/Fe3O4 submicron composites were prepared using a hydrothermal method and used as heterogeneous catalysts for the activation of peroxymonosulfate（PMS） and the degradation of organic pollutants.The as-prepared magnetic Cu^0/Fe3O4 submicron composites were composed of Cu^0 and Fe3O4 crystals and had an average size of approximately 220 nm.The Cu^0/Fe3O4 composites could efficiently catalyze the activation of PMS to generate singlet oxygen,and thus induced the rapid degradation of rhodamine B,methylene blue,orange Ⅱ,phenol and 4-chlorophenol.The use of0.1 g/L of the Cu^0/Fe3O4 composites induced the complete removal of rhodamine B（20 μmol/L） in15 min,methylene blue（20 μmol/L） in 5 min,orange Ⅱ（20 μmol/L） in 10 min,phenol（0.1mmol/L） in 30 min and 4-chlorophenol（0.1 mmol/L） in 15 min with an initial pH value of 7.0 and a PMS concentration of 0.5 mmol/L.The total organic carbon（TOC） removal higher than 85%for all of these five pollutants was obtained in 30 min when the PMS concentration was 2.5 mmol/L.The rate of degradation was considerably higher than that obtained with Cu^0 or Fe3O4 particles alone.The enhanced catalytic activity of the Cu^0/Fe3O4 composites in the activation of PMS was attributed to the synergistic effect of the Cu^0 and Fe3O4 crystals in the composites.Singlet oxygen was identified as the primary reactive oxygen species responsible for pollutant degradation by electron spin resonance and radical quenching experiments.A possible mechanism for the activation of PMS by Cu^0/Fe3O4 composites is proposed as electron transfer from the organic pollutants to PMS induces the activation of PMS to generate ^1O2,which induces the degradation of the organic pollutants.As a magnetic catalyst,the Cu^0/Fe3O4 composites were easily recovered by magnetic separation,and exhibited excellent stability over five successive degradation cycles.The present study provides a facile and green heterogeneous catalysis method for the oxidative removal of organic pollutants.
文摘零价铁渗透式反应墙技术(zero-valent iron permeable reactive barrier,Fe^0-PRB)是近年来兴起的一项高效经济的地下水原位修复技术,被成功应用于地下水Cr(Ⅵ)污染的场地修复中.针对Fe^0-PRB去除Cr(Ⅵ)的反应影响机制开展研究,从动力学角度揭示零价铁去除Cr(Ⅵ)的环境条件响应规律,获得描述零价铁去除Cr(Ⅵ)的反应动力学模型.考察了地下水常见离子对Cr(Ⅵ)去除的影响,发现地下水中氯离子通过影响电子传递影响Cr(Ⅵ)去除,硫酸根、镁离子通过参与反应影响Cr(Ⅵ)去除,碳酸氢根通过参与反应和影响电子传递共同影响Cr(Ⅵ)去除,钙离子对Cr(Ⅵ)去除影响不大.研究结果为Fe^0-PRB去除Cr(Ⅵ)的工艺参数优化提供方法和理论依据.
