Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that ...Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that combining ZVI with SRB can enhance the removal of U(Ⅵ) synergistically. The removal rate of U(Ⅵ) in the ZVI+SRB combining system is obviously higher than the total rate of ZVI system and SRB system with a difference of 13.4% at t=2 h and 29.9% at t=4 h. Column experiments indicate that the reactor filled with both ZVI and SRB biofilms is of better performance than the SRB bioreactor in wastewater basification, desulfurization and U(Ⅵ) fixation. The results imply that the ZVI+SRB permeable reactive barrier may be a promising method for treating subsurface uranium contamination.展开更多
Sulfated zero-valent iron(SZVI)has shown promising applications in wastewater treatment.However,the rapid decline in the reactivity of SZVI with time limits its real practice.To mediate this problem,partial aging was ...Sulfated zero-valent iron(SZVI)has shown promising applications in wastewater treatment.However,the rapid decline in the reactivity of SZVI with time limits its real practice.To mediate this problem,partial aging was proposed to improve the reactive durability of SZVI.Taking Cr(VI)as the target contaminant,we found that the aged ZVI(AZVI)gradually lost reactivity as aging time increased from 0.5 to 2 d.Counter-intuitively,the partially aged SZVI(ASZVI)showed greater reactivity than SZVI when exposed to oxygenated water for a period ranging from 0.5 to 14 d.In addition,the ASZVI with 0.5 d of aging time(ASZVI-0.5)not only maintained reactivity in successive runs but also increased the Cr(VI)removal capacity from 9.1 mg/g by SZVI to 19.1 mg/g by ASZVI-0.5.Correlation analysis further revealed that the electron transfer from the Fe0 core to the shell was mediated by the conductive FeS and FeS2 in the subshell of ASZVI.Meanwhile,the lepidocrocite and magnetite on the surface of ASZVI facilitated Cr(VI)adsorption and subsequent electron transfer for Cr(VI)reduction.Moreover,the iron(hydr)oxide shell could retain the conductive FeS and FeS2 in the subshell,allowing ASZVI to reduce Cr(VI)efficiently and sustainably.In general,partial aging can enhance the reactive durability of ZVI when coupled with sulfidation and this synergistic effect will be beneficial to the application of SZVI-based technology for wastewater treatment.展开更多
Endosulfan, an organochlorine pesticide, is known for its toxicity and ability to accumulate in the environment. In India endosulfan was banned only in 2011 and hence toxic residues are still persistent in the environ...Endosulfan, an organochlorine pesticide, is known for its toxicity and ability to accumulate in the environment. In India endosulfan was banned only in 2011 and hence toxic residues are still persistent in the environment. The abilities of three plant species Chittaratha (Alpinia calcarata), Tulsi (Ocimum sanctum), and Lemongrass (Cymbopogon citratus) to remove endosulfan from soil in the absence and presence of zerovalent iron nanoparticles (nZVIs) (1000 mg/Kg of soil), i.e., by phytoremediation and nano-phytoremediation, were determined. Extracted soil samples from the experimental plot were analyzed using Gas Chromatograph with Electron Capture Detector (GC-ECD) and final dehalogenated product was confirmed by Mass Spectrometer (MS). A. calcarata had the best efficiency compared to the other two plant species and the efficiency decreased in the order A. calcarata > O. sanctum> C. citrates. The initial endosulfan removal rate was high (82% was removed within 7 days) when nano phytoremediation experiments were conducted with A. calcarata but then gradually decreased, probably because the activity of nZVI decreased over time. The nZVI endosulfan degradation mechanism appears to involve hydrogenolysis and sequential dehalogenation which was confirmed by GC-MS analysis. Only small amounts of endosulfan were accumulated in the plants because the added nZVIs might have promoted the reductive dechlorination of endosulfan.展开更多
Nanoscale zerovalent iron （nZVI） synthesized using sepiolite as a supporter was used to investigate the removal kinetics and mechanisms of decabromodiphenyl ether （BDE-209）. BDE-209 was rapidly removed by the prep...Nanoscale zerovalent iron （nZVI） synthesized using sepiolite as a supporter was used to investigate the removal kinetics and mechanisms of decabromodiphenyl ether （BDE-209）. BDE-209 was rapidly removed by the prepared sepiolite-supported nZVI with a reaction rate that was 5 times greater than that of the conventionally prepared nZVI because of its high surface area and reactivity. The degradation of BDE-209 occurred in a stepwise debromination manner, which followed pseudo- first-order kinetics. The removal efficiency of BDE-209 increased with increasing dosage of sepiolite-supported nZVI particles and decreasing pH, and the efficiency decreased with increasing initial BDE-209 concentrations. The presence of tetrahydrofuran （THF） as a cosolvent at certain volume fractions in water influenced the degrada- tion rate of sepiolite-supported nZVI. Debromination pathways of BDE-209 with sepiolite-supported nZVI were proposed based on the identified reaction intermedi- ates, which ranged from nona- to mono-brominated diphenylethers （BDEs） under acidic conditions and nonato penta-BDEs under alkaline conditions. Adsorption on sepiolite-supported nZVI particles also played a role in the removal of BDE-209. Our findings indicate that the particles have potential applications in removing environ- mental pollutants, such as halogenated organic contami- nants.展开更多
Zerovalent iron nanoparticles have been successfully synthesized using sodium borohydride solution reduction of ferric trichloride hexahydrate in the presence of montmorillonite as an effective protective reagent and ...Zerovalent iron nanoparticles have been successfully synthesized using sodium borohydride solution reduction of ferric trichloride hexahydrate in the presence of montmorillonite as an effective protective reagent and support as well. A combination of characterizations reveals that with high monodispersity these obtained iron nanoparticles are well dispersed on clay surface, virginal from boron related impurity, and oxidation resistant well with iron core-iron oxide shell structure. The shell thickness of 3 nm remains almost invariable under ambient conditions. The size control of these iron nanoparticles has been achieved by tailoring the amount of the ferric iron, which mainly depends on the protective action of montmorillonite.展开更多
Biochar supported nano-scale zerovalent iron(nZVI/BC)for persulfate(PS)activation has been studied extensively for the degradation of pollutants on the lab scale,but it was rarely applied in practical soil remediation...Biochar supported nano-scale zerovalent iron(nZVI/BC)for persulfate(PS)activation has been studied extensively for the degradation of pollutants on the lab scale,but it was rarely applied in practical soil remediation in the field.In this research,we developed a facile ball-milling method for the mass production of nZVI/BC,which was successfully applied to activate persulfate for the remediation of organic polluted soil on an in-situ pilot scale.In-situ high-pressure injection device was developed to inject nZVI/BC suspension and PS solution into the soil with a depth of 0-70 cm.The removal efficiency of target pollutants such as 2-ethylnitrobenzene(ENB,1.47-1.56 mg/kg),biphenyl(BP,0.19-0.21 mg/kg),4-(methylsulfonyl)toluene(MST,0.32-0.43 mg/kg),and 4-phenylphenol(PP,1.70-2.46 mg/kg)at different soil depths was 99.7%,99.1%,99.9%and 99.7%,respectively,after 360 days of remediation.The application of nZVI/BC significantly increased the degradation rates of contaminants by 11-322%,ascribed to its relatively higher efficiency of free radical generation than that of control groups.In addition,it was found that nZVI/BC-PS inhibited soil urease and sucrase enzyme activities by 1-61%within 55 days due to the oxidative stress for microbes induced by free radicals,while these inhibition effects disappeared with remediation time prolonged(>127 days).Our research provides a useful implementation case of remediation with nZVI/BC-PS activation and verifies its feasibility in practical contaminated soil remediation.展开更多
以FeSO4和NaBH4水溶液为前驱溶剂,以聚苯乙烯型阳离子交换树脂为载体,制备了树脂固载的纳米铁,室温下用于对偶氮染料直接湖蓝5B水溶液进行脱色研究。研究结果发现,脱色反应遵循准一级反应动力学,在初始pH为310的范围内,反应进行14 m in...以FeSO4和NaBH4水溶液为前驱溶剂,以聚苯乙烯型阳离子交换树脂为载体,制备了树脂固载的纳米铁,室温下用于对偶氮染料直接湖蓝5B水溶液进行脱色研究。研究结果发现,脱色反应遵循准一级反应动力学,在初始pH为310的范围内,反应进行14 m in时,50 mg/L的染料溶液脱色率均能达到83%以上。固载的纳米铁材料可多次重复利用,溶液中释放的铁离子浓度不超过0.1 mg/L。展开更多
基金Project(kzcx2-yw-135-2) supported by Knowledge Innovational Program of Chinese Academy of SciencesProject(08B07) supported by Science Foundation of Hengyang Normal University
文摘Batch and column experiments were conducted to determine whether zerovalent iron (ZVI) and sulfate reducing bacteria (SRB) can function synergistically and accelerate pollutant removal. Batch experiments suggest that combining ZVI with SRB can enhance the removal of U(Ⅵ) synergistically. The removal rate of U(Ⅵ) in the ZVI+SRB combining system is obviously higher than the total rate of ZVI system and SRB system with a difference of 13.4% at t=2 h and 29.9% at t=4 h. Column experiments indicate that the reactor filled with both ZVI and SRB biofilms is of better performance than the SRB bioreactor in wastewater basification, desulfurization and U(Ⅵ) fixation. The results imply that the ZVI+SRB permeable reactive barrier may be a promising method for treating subsurface uranium contamination.
基金supported by the National Key R&D Program of China(No.2021YFA1201701)the National Natural Science Foundation of China(No.22025601)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_0495).
文摘Sulfated zero-valent iron(SZVI)has shown promising applications in wastewater treatment.However,the rapid decline in the reactivity of SZVI with time limits its real practice.To mediate this problem,partial aging was proposed to improve the reactive durability of SZVI.Taking Cr(VI)as the target contaminant,we found that the aged ZVI(AZVI)gradually lost reactivity as aging time increased from 0.5 to 2 d.Counter-intuitively,the partially aged SZVI(ASZVI)showed greater reactivity than SZVI when exposed to oxygenated water for a period ranging from 0.5 to 14 d.In addition,the ASZVI with 0.5 d of aging time(ASZVI-0.5)not only maintained reactivity in successive runs but also increased the Cr(VI)removal capacity from 9.1 mg/g by SZVI to 19.1 mg/g by ASZVI-0.5.Correlation analysis further revealed that the electron transfer from the Fe0 core to the shell was mediated by the conductive FeS and FeS2 in the subshell of ASZVI.Meanwhile,the lepidocrocite and magnetite on the surface of ASZVI facilitated Cr(VI)adsorption and subsequent electron transfer for Cr(VI)reduction.Moreover,the iron(hydr)oxide shell could retain the conductive FeS and FeS2 in the subshell,allowing ASZVI to reduce Cr(VI)efficiently and sustainably.In general,partial aging can enhance the reactive durability of ZVI when coupled with sulfidation and this synergistic effect will be beneficial to the application of SZVI-based technology for wastewater treatment.
文摘Endosulfan, an organochlorine pesticide, is known for its toxicity and ability to accumulate in the environment. In India endosulfan was banned only in 2011 and hence toxic residues are still persistent in the environment. The abilities of three plant species Chittaratha (Alpinia calcarata), Tulsi (Ocimum sanctum), and Lemongrass (Cymbopogon citratus) to remove endosulfan from soil in the absence and presence of zerovalent iron nanoparticles (nZVIs) (1000 mg/Kg of soil), i.e., by phytoremediation and nano-phytoremediation, were determined. Extracted soil samples from the experimental plot were analyzed using Gas Chromatograph with Electron Capture Detector (GC-ECD) and final dehalogenated product was confirmed by Mass Spectrometer (MS). A. calcarata had the best efficiency compared to the other two plant species and the efficiency decreased in the order A. calcarata > O. sanctum> C. citrates. The initial endosulfan removal rate was high (82% was removed within 7 days) when nano phytoremediation experiments were conducted with A. calcarata but then gradually decreased, probably because the activity of nZVI decreased over time. The nZVI endosulfan degradation mechanism appears to involve hydrogenolysis and sequential dehalogenation which was confirmed by GC-MS analysis. Only small amounts of endosulfan were accumulated in the plants because the added nZVIs might have promoted the reductive dechlorination of endosulfan.
文摘Nanoscale zerovalent iron （nZVI） synthesized using sepiolite as a supporter was used to investigate the removal kinetics and mechanisms of decabromodiphenyl ether （BDE-209）. BDE-209 was rapidly removed by the prepared sepiolite-supported nZVI with a reaction rate that was 5 times greater than that of the conventionally prepared nZVI because of its high surface area and reactivity. The degradation of BDE-209 occurred in a stepwise debromination manner, which followed pseudo- first-order kinetics. The removal efficiency of BDE-209 increased with increasing dosage of sepiolite-supported nZVI particles and decreasing pH, and the efficiency decreased with increasing initial BDE-209 concentrations. The presence of tetrahydrofuran （THF） as a cosolvent at certain volume fractions in water influenced the degrada- tion rate of sepiolite-supported nZVI. Debromination pathways of BDE-209 with sepiolite-supported nZVI were proposed based on the identified reaction intermedi- ates, which ranged from nona- to mono-brominated diphenylethers （BDEs） under acidic conditions and nonato penta-BDEs under alkaline conditions. Adsorption on sepiolite-supported nZVI particles also played a role in the removal of BDE-209. Our findings indicate that the particles have potential applications in removing environ- mental pollutants, such as halogenated organic contami- nants.
基金supported by the National Natural Science Foundation of China (Grant No. 40672036)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. Kzcx2-yw-112)+1 种基金National Science Fund for Distinguished Young Scholars (Grant No. 40725006)Program of Higher-level talents of Inner Mongolia University (Grant No. Z20090131)
文摘Zerovalent iron nanoparticles have been successfully synthesized using sodium borohydride solution reduction of ferric trichloride hexahydrate in the presence of montmorillonite as an effective protective reagent and support as well. A combination of characterizations reveals that with high monodispersity these obtained iron nanoparticles are well dispersed on clay surface, virginal from boron related impurity, and oxidation resistant well with iron core-iron oxide shell structure. The shell thickness of 3 nm remains almost invariable under ambient conditions. The size control of these iron nanoparticles has been achieved by tailoring the amount of the ferric iron, which mainly depends on the protective action of montmorillonite.
基金the National Key Research and Development Program of China(2018YFC1802006,2017YFA0207001)the National Natural Science Foundation of China(42022049,42130707,and 42107045)the 145 Program of Institute of Soil Science(ISSASIP2213).
文摘Biochar supported nano-scale zerovalent iron(nZVI/BC)for persulfate(PS)activation has been studied extensively for the degradation of pollutants on the lab scale,but it was rarely applied in practical soil remediation in the field.In this research,we developed a facile ball-milling method for the mass production of nZVI/BC,which was successfully applied to activate persulfate for the remediation of organic polluted soil on an in-situ pilot scale.In-situ high-pressure injection device was developed to inject nZVI/BC suspension and PS solution into the soil with a depth of 0-70 cm.The removal efficiency of target pollutants such as 2-ethylnitrobenzene(ENB,1.47-1.56 mg/kg),biphenyl(BP,0.19-0.21 mg/kg),4-(methylsulfonyl)toluene(MST,0.32-0.43 mg/kg),and 4-phenylphenol(PP,1.70-2.46 mg/kg)at different soil depths was 99.7%,99.1%,99.9%and 99.7%,respectively,after 360 days of remediation.The application of nZVI/BC significantly increased the degradation rates of contaminants by 11-322%,ascribed to its relatively higher efficiency of free radical generation than that of control groups.In addition,it was found that nZVI/BC-PS inhibited soil urease and sucrase enzyme activities by 1-61%within 55 days due to the oxidative stress for microbes induced by free radicals,while these inhibition effects disappeared with remediation time prolonged(>127 days).Our research provides a useful implementation case of remediation with nZVI/BC-PS activation and verifies its feasibility in practical contaminated soil remediation.
文摘以FeSO4和NaBH4水溶液为前驱溶剂,以聚苯乙烯型阳离子交换树脂为载体,制备了树脂固载的纳米铁,室温下用于对偶氮染料直接湖蓝5B水溶液进行脱色研究。研究结果发现,脱色反应遵循准一级反应动力学,在初始pH为310的范围内,反应进行14 m in时,50 mg/L的染料溶液脱色率均能达到83%以上。固载的纳米铁材料可多次重复利用,溶液中释放的铁离子浓度不超过0.1 mg/L。
