Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The p...Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction （XRD）. The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm^2 for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively.展开更多
The oxidative degradation of 4-chlorophenol （4-CP） in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined ...The oxidative degradation of 4-chlorophenol （4-CP） in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined by high performance liquid chromatography （HPLC）. Various influencing factors such as the initial pH, the concentration of 4-CP and the catalytic action of Fe^2＋ were examined. The results indicate that 4-CP is eventually degraded into inorganic ion, dioxide carbon and water. The attack of hydroxyl radicals on the benzene rings of 4-CP in the initial stage of oxidative reactions is presumed to be a key step. They also suggest that the reaction is of a pseudo-first order kinetic reaction and the proposed method is an efficient way for the 4-CP degradation,展开更多
Candida albicans PDY-07 was isolated from activated sludge under anaerobic conditions and identified as a member belonging to the genus Candida. Pure culture of C. albicans PDY-07, biodegradation of 4-chlorophenol 4-C...Candida albicans PDY-07 was isolated from activated sludge under anaerobic conditions and identified as a member belonging to the genus Candida. Pure culture of C. albicans PDY-07, biodegradation of 4-chlorophenol 4-CP was carried out under anaerobic conditions in Erlenmeyer flasks at 35℃, with an initial pH of 7.0—7.2 and a starting inoculum of 10% by volume. The results showed that, under the above-mentioned con- ditions, C. albicans PDY-07 could thoroughly biodegrade 4-CP up to a concentration of 300mg·L-1 within 244h and that it had a high tolerance potential of up to 440mg·L-1 for 4-CP. With the increase in the initial concentrations of 4-CP, substrate inhibition was obviously enhanced. There was increased consumption of 4-CP, which was not assimilated by the cell for growth but was used to counteract the strong substrate inhibition. In addition, the cell growth and substrate-degradation kinetics of 4-CP as the sole source of carbon and energy for the strain in batch cultures were also investigated over a wide range of substrate concentrations 2.2—350mg·L-1, using the proposed cell growth and degradation kinetic models. The results recorded from these experiments showed that the proposed kinetic models adequately described the dynamic behavior of 4-CP biodegradation by C. albicans PDY-07.展开更多
In this work, a new immobilization method based on dopamine(DA) self-polymerization was developed for laccase immobilization on magnetic nanoparticles(Fe_3O_4 NPs). To optimize the immobilization condition including r...In this work, a new immobilization method based on dopamine(DA) self-polymerization was developed for laccase immobilization on magnetic nanoparticles(Fe_3O_4 NPs). To optimize the immobilization condition including reaction pH, DA concentration and enzyme concentration, a central composite response surface method was applied. The optimal condition was determined as p H value of 5.92, laccase concentration of 0.25 mg mL^(-1) and DA concentration of 12.74 mg mL^(-1), under which a high enzyme activity recovery of 88.17% was obtained.By comparing with free laccase, the stabilities of immobilized laccase towards p H, thermostability, storage were enhanced significantly.Approximately 60% of relative activity for immobilized laccase was remained after being incubated for 6 h at 50℃, but the free laccase only remained 25%. After 40 days of storage at 4℃, the laccase immobilized by DA kept about 89% of its original activity, but the free laccase only retained 48%. After recycled 10 times, the relative activity of immobilized laccase still retained 70%. The immobilized laccase was then applied to catalyze the degradation of 4-chlorophenol(4-CP), 86% percentage of 4-CP was removed within 2 h. After degraded 10 times, the relative activity of immobilized laccase still remained 64% of its initial activity, which exhibits an excellent reusability and operational stability.展开更多
A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanica...A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanical strength and the thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.展开更多
4-Chlorophenol (4-CP) solution was treated by dual-frequency ultrasound in conjunction with Fenton reagent, and obvious improvement in the 4-CP degradation rate was observed in this advanced oxidation process.Experime...4-Chlorophenol (4-CP) solution was treated by dual-frequency ultrasound in conjunction with Fenton reagent, and obvious improvement in the 4-CP degradation rate was observed in this advanced oxidation process.Experimental results showed that ultrasonic intensity, saturating gas and pH value affected greatly the 4-CP removal rate. Among four different saturating gases (Ar, 02, air and N2), 4-CP degradation with Ar-saturated solution was the best. However, in the view of practical wastewater treatment, using oxygen as the saturating gas would be more economical. The addition of Fenton reagent followed the first-order kinetics and increased the 4-CP degradation rate.The 4-CP removal rate increased by around 126% within 15 rain treatment. The synergetic effect of dual-frequency ultrasound with Fenton reagent on 4-CP degradation was obviously observed.展开更多
This paper aims to create visible light driven ternary photocatalysts using zinc oxide(ZnO),cerium(IV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent materials.The use of CeO_(2) is based on the creation of direc...This paper aims to create visible light driven ternary photocatalysts using zinc oxide(ZnO),cerium(IV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent materials.The use of CeO_(2) is based on the creation of direct-Z-scheme heterojunctions with the ZnO and the consequent diminishing of charge recombination,whereas the carbon xerogel inclusion is predicted to minimize bandgap energy,decrease electro n-hole reco mbination,and boost specific surface area.Furthermo re,the choice of the black-wattle tannin as a carbonaceous precursor was targeted at the development of an environmentally friendly and affordable composite.The existence of the hexagonal phase of zinc oxide and cubic structure of the cerium(IV) oxide in the ternary material was confirmed by X-ray diffractometry and X-ray photoelectron spectroscopy,with the latter also suggesting chemical bonding between the ZnO and the CX due to the creation of zinc oxycarbide complexes.The inclusion of the carbon xerogel provokes a significant modification in the morphology of the ternary material,resulting in an increased surface area and smaller particle aggregates.The CX/ZnO-CeO_(2) ternary composite obtains the highest photocatalytic efficiency among all the materials studied,degrading 100% of 4-chlorophenol under simulated sunlight and 68% under visible radiation,after 5 h.The increased photocatalytic activity can be attributed to the formation of direct Z-scheme heterojunctions between the semiconductors,higher visible light response,and higher specific surface area,as evidenced by the results obtained by active radical scavenging,chronoamperometry,diffuse reflectance spectroscopy,and N_(2) adsorption-desorption isotherms.展开更多
A novel solid-liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water.The sensor comprised horseradish peroxidase(HRP)-coated U-shaped liquidcore optica...A novel solid-liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water.The sensor comprised horseradish peroxidase(HRP)-coated U-shaped liquidcore optical fiber(LCOF)and 4-chlorophenol permselective polymer membrane.The U-shaped LCOF was flled with ethanol suspension of SiO_(2)particles and the polymer membrane was composed of molecularly imprinted polymer,sulfonated polyethersulfone,and polysulfone.The morphology,composition,and surface luminous properties of the sensing region were examined.The effects of the diameter and content of SiO_(2)particles and temperature of 4-chlorophenol solutions on the sensitivity of the biosensors were investigated.Further,the sensitivity,selectivity,response time,and limit of detection(LOD)of the biosensors was investigated.In addition,the effects of fiber core materials on the light transmission in sensing region were investigated and a biosensor sensing model was established.The proposed sensor exhibited high selectivity for 4-chlorophenol with satisfactory sensitivity,LOD,and response time:-1.18(μg/L)^(-1),30μg/L,and 400 s,respectively.The results are expected to aid in the development of methods for enhancing sensitivity of fiber-optic sensors and surface luminous intensity of optical fibers.展开更多
基金Project supported by the Institute of Environmental Engineering,Peking University and China Postdoctoral Science Foundation(No.2005037032)
文摘Ti/Sb-SnO2 anodes were prepared by thermal decomposition to examine the influence of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol. The physicochemical properties of the Sb-SnO2 coating were markedly influenced by different amounts of Sb dopant. The electrodes, which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks, compared with Ti/Sb-SnO2 electrodes containing 10% or 15% Sb dopant, which exibited larger mud cracks and pores on the surface. However, the main microstructure remained unchanged with the addition of the Sb dopant. No new crystal phase was observed by X-ray diffraction （XRD）. The electrochemical oxidation of 4-chlorophenol on the Ti/SnO2 electrode with 5% Sb dopant was inclined to electrochemical combustion; while for those containing more Sb dopant, intermediate species were accumulated. The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm^2 for 180 min; and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%, respectively.
基金The project partially supported by the Project of Key Science and Technology of Education Ministry (00250), the Natural ScienceFoundation of Gansu Province (3ZS041-A25-028), and the Project of KJCXGC-01, NWNU, China
文摘The oxidative degradation of 4-chlorophenol （4-CP） in aqueous solution induced by plasma with submersed glow discharge has been investigated. The concentration of 4-CP and the reaction intermediates were determined by high performance liquid chromatography （HPLC）. Various influencing factors such as the initial pH, the concentration of 4-CP and the catalytic action of Fe^2＋ were examined. The results indicate that 4-CP is eventually degraded into inorganic ion, dioxide carbon and water. The attack of hydroxyl radicals on the benzene rings of 4-CP in the initial stage of oxidative reactions is presumed to be a key step. They also suggest that the reaction is of a pseudo-first order kinetic reaction and the proposed method is an efficient way for the 4-CP degradation,
基金the National Natural Science Foundation of China (No.20336030) the Natural Science Foundation of Tianjin(No.05YFJZJC 00500)
文摘Candida albicans PDY-07 was isolated from activated sludge under anaerobic conditions and identified as a member belonging to the genus Candida. Pure culture of C. albicans PDY-07, biodegradation of 4-chlorophenol 4-CP was carried out under anaerobic conditions in Erlenmeyer flasks at 35℃, with an initial pH of 7.0—7.2 and a starting inoculum of 10% by volume. The results showed that, under the above-mentioned con- ditions, C. albicans PDY-07 could thoroughly biodegrade 4-CP up to a concentration of 300mg·L-1 within 244h and that it had a high tolerance potential of up to 440mg·L-1 for 4-CP. With the increase in the initial concentrations of 4-CP, substrate inhibition was obviously enhanced. There was increased consumption of 4-CP, which was not assimilated by the cell for growth but was used to counteract the strong substrate inhibition. In addition, the cell growth and substrate-degradation kinetics of 4-CP as the sole source of carbon and energy for the strain in batch cultures were also investigated over a wide range of substrate concentrations 2.2—350mg·L-1, using the proposed cell growth and degradation kinetic models. The results recorded from these experiments showed that the proposed kinetic models adequately described the dynamic behavior of 4-CP biodegradation by C. albicans PDY-07.
基金support from the National Natural Science Foundation of China(Grant Nos.51378487,51425405,21376249,21336010)Youth Innovation Promotion Association,CAS(2014037)973 Program(2013CB733604)
文摘In this work, a new immobilization method based on dopamine(DA) self-polymerization was developed for laccase immobilization on magnetic nanoparticles(Fe_3O_4 NPs). To optimize the immobilization condition including reaction pH, DA concentration and enzyme concentration, a central composite response surface method was applied. The optimal condition was determined as p H value of 5.92, laccase concentration of 0.25 mg mL^(-1) and DA concentration of 12.74 mg mL^(-1), under which a high enzyme activity recovery of 88.17% was obtained.By comparing with free laccase, the stabilities of immobilized laccase towards p H, thermostability, storage were enhanced significantly.Approximately 60% of relative activity for immobilized laccase was remained after being incubated for 6 h at 50℃, but the free laccase only remained 25%. After 40 days of storage at 4℃, the laccase immobilized by DA kept about 89% of its original activity, but the free laccase only retained 48%. After recycled 10 times, the relative activity of immobilized laccase still retained 70%. The immobilized laccase was then applied to catalyze the degradation of 4-chlorophenol(4-CP), 86% percentage of 4-CP was removed within 2 h. After degraded 10 times, the relative activity of immobilized laccase still remained 64% of its initial activity, which exhibits an excellent reusability and operational stability.
基金Supported by the science and Technology Innovative Talents Foundation of China （2006RFQXS070）, the Youth Academic Cadreman Project of Heilongjiang Province （1152G068）, Scientific Research Fund of Heilongjiang Province （11523063） and the Science Foundation for Post Doctorate of China （20070410268）.
文摘A new cell immobilization method based on the replacement of KCl by KCl+chitosan as the gelling agent was developed. The experimental results showed that through addition of chitosan into gelling agent, the mechanical strength and the thermal stability of the carrageenan gel were greatly improved. The new immobilization method was used to entrap a chlorophenol degrading microorganism. The immobilized microbial cells were applied for chlorophenol biodegradation. The experiments demonstrated that immobilized cells exhibit a higher bioactivity in the degradation of chlorophenol than free cells.
基金Partly supported by the National Natural Science Foundation of China (No. 20176053)Academic Foundation of Zhejiang University of Technology (No. 20040004).
文摘4-Chlorophenol (4-CP) solution was treated by dual-frequency ultrasound in conjunction with Fenton reagent, and obvious improvement in the 4-CP degradation rate was observed in this advanced oxidation process.Experimental results showed that ultrasonic intensity, saturating gas and pH value affected greatly the 4-CP removal rate. Among four different saturating gases (Ar, 02, air and N2), 4-CP degradation with Ar-saturated solution was the best. However, in the view of practical wastewater treatment, using oxygen as the saturating gas would be more economical. The addition of Fenton reagent followed the first-order kinetics and increased the 4-CP degradation rate.The 4-CP removal rate increased by around 126% within 15 rain treatment. The synergetic effect of dual-frequency ultrasound with Fenton reagent on 4-CP degradation was obviously observed.
基金Project supported by the Sao Paulo Research Foundation(FAPESP)(2018/10492-1,2018/16360-0,2007/08244-5,2007/54829-5,2017/18574-4,2017/10118-0,2014/50945-4)the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico(CNPq)(465571/2014-0,302874/2017-8,427452/2018-0)。
文摘This paper aims to create visible light driven ternary photocatalysts using zinc oxide(ZnO),cerium(IV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent materials.The use of CeO_(2) is based on the creation of direct-Z-scheme heterojunctions with the ZnO and the consequent diminishing of charge recombination,whereas the carbon xerogel inclusion is predicted to minimize bandgap energy,decrease electro n-hole reco mbination,and boost specific surface area.Furthermo re,the choice of the black-wattle tannin as a carbonaceous precursor was targeted at the development of an environmentally friendly and affordable composite.The existence of the hexagonal phase of zinc oxide and cubic structure of the cerium(IV) oxide in the ternary material was confirmed by X-ray diffractometry and X-ray photoelectron spectroscopy,with the latter also suggesting chemical bonding between the ZnO and the CX due to the creation of zinc oxycarbide complexes.The inclusion of the carbon xerogel provokes a significant modification in the morphology of the ternary material,resulting in an increased surface area and smaller particle aggregates.The CX/ZnO-CeO_(2) ternary composite obtains the highest photocatalytic efficiency among all the materials studied,degrading 100% of 4-chlorophenol under simulated sunlight and 68% under visible radiation,after 5 h.The increased photocatalytic activity can be attributed to the formation of direct Z-scheme heterojunctions between the semiconductors,higher visible light response,and higher specific surface area,as evidenced by the results obtained by active radical scavenging,chronoamperometry,diffuse reflectance spectroscopy,and N_(2) adsorption-desorption isotherms.
基金support from the National Natural Science Foundation of China(NSFC)(Nos.U19A20107,52176178 and 51876018)Innovation Research Group of Universities in Chongqing(No.CXQT21035)+1 种基金Chongqing Natural Science Foundation Innovation and Development Joint Fund Project(No.CSTB2022NSCQ-LZX0059)the Scientific and Technological Research Program of Chongqing Municipal Education Commission of China(No.KJZD-M202201101).
文摘A novel solid-liquid-core fiber-optic biosensor was fabricated for highly sensitive and selective detection of 4-chlorophenol in water.The sensor comprised horseradish peroxidase(HRP)-coated U-shaped liquidcore optical fiber(LCOF)and 4-chlorophenol permselective polymer membrane.The U-shaped LCOF was flled with ethanol suspension of SiO_(2)particles and the polymer membrane was composed of molecularly imprinted polymer,sulfonated polyethersulfone,and polysulfone.The morphology,composition,and surface luminous properties of the sensing region were examined.The effects of the diameter and content of SiO_(2)particles and temperature of 4-chlorophenol solutions on the sensitivity of the biosensors were investigated.Further,the sensitivity,selectivity,response time,and limit of detection(LOD)of the biosensors was investigated.In addition,the effects of fiber core materials on the light transmission in sensing region were investigated and a biosensor sensing model was established.The proposed sensor exhibited high selectivity for 4-chlorophenol with satisfactory sensitivity,LOD,and response time:-1.18(μg/L)^(-1),30μg/L,and 400 s,respectively.The results are expected to aid in the development of methods for enhancing sensitivity of fiber-optic sensors and surface luminous intensity of optical fibers.
