Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(...Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(SMS),to produce an iron-carbon composite(SMS-nZVI).The ability of the SMS-nZVI to treat wastewater containing high concentration of oil was then comprehensively evaluated.The morphology,structure,and other properties of the composite were characterized by using scanning electron microscopy,transmission electron microscopy,the Brunauer-Emmett-Teller nitrogen sorption analysis,and the Fourier transform infrared spectroscopy.The results show that the biochar prepared by using the SMS can effectively prevent the agglomeration of nZVI and increase the overall specific surface area,thereby enhancing the absorption of petroleum by the composite.Experiments reveal that compared with the SMS and nZVI,the SMS-nZVI composite removes petroleum faster and more efficiently from wastewater.Under optimized conditions involving an nZVI to biochar mass ratio of 1:5 and a pH value of 4,the efficiency for removal of petroleum from wastewater with an initial petroleum concentration of 1000 mg/L could reach 95%within 5 h.Based on a natural aging treatment involving exposure to air for 30 d,the SMS-nZVI composite retained an oil removal rate of higher than 62%,and this result could highlight its stability for practical applications.展开更多
Nano zero valent iron particles (nZVI) are popular the last few years because of the numerous applications in remediation of a wide range of pollutants in contaminated soils and aquifers. The nZVI particles can be 10 ...Nano zero valent iron particles (nZVI) are popular the last few years because of the numerous applications in remediation of a wide range of pollutants in contaminated soils and aquifers. The nZVI particles can be 10 - 1000 times more reactive than granular or micro-scale ZVI particles due to the small particle size, large specific surface area and high reactivity. An alternative green synthesis procedure was used for the production of nano zero valent iron particles (nZVI) using green tea (GT) extract, which is characterized by its high antioxidant content. Polyphenols in green tea extract possess double role in the synthesis of nZVI, because they not only reduce ferric cations, but also protect nZVI from oxidation and agglomeration as capping agents. The objective of current study was to simulate ata laboratory scale the attachment of GT-nZVI particles on soil material and study the effectiveness of attached nanoparticles for removing hexavalent chromium (Cr(VI)) from contaminated groundwater flowing through the porous soil bed. Column tests were carried out with various flowrates in order to examine the effect of contact time between the attached on porous medium nZVI and the flow-through solution on Cr(VI) reduction. After the completion of column tests the soil material in each column was split in 5 vertical sections, which were further subjected to chemical analyses and leaching tests. According to the results of the study increasing the contact time favors the reduction and removal of Cr(VI) from the aqueous phase. The reductive precipitation of Cr can be described as a reaction that follows a pseudo-first order kinetic law, with rate constant equal to k = 0.0243 ± 0.0011 min-1. Leaching tests indicated that precipitated chromium is not soluble. In the examined soil material, the total amount of precipitated Cr was found to range between 280 and 890 mg/(kg soil), while soluble Cr was less than 1.4 mg/kg and most probably it was due to the presence of residual Cr(VI) solution in the porosity of soil.展开更多
Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF d...Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF degradation by the combined process of zero-valent iron nanoparticles(nZVI)and nano calcium peroxide(nCaO_(2))were performed.A batch experiment was conducted to examine the influence of the adding dosages of both nZVI and nCaO_(2)nanoparticles and pH value on the DCF removal.In the meantime,the continuous-flow experiment was done to explore the sustainability of the DCF degradation by jointly adding nZVI/nCaO_(2)nanoparticles in the reaction system.The results show that the nZVI/nCaO_(2)can effectively remove the DCF in the batch test with only 0.05 g/L nZVI and 0.2 g/L nCaO_(2)added,resulting in a removal rate of greater than 90%in a 2-hour reaction with an initial pH of 5.The degradation rate of DCF was positively correlated with the dosage of nCaO_(2),and negatively correlated with both nZVI dosage and the initial pH value.The order of significance of the three factors is identified as pH value>nZVI dosage>nCaO_(2)dosage.In the continuous-flow reaction system,the DCF removal rates remained above 75%within 150 minutes at the pH of 5,with the applied dosages of 0.5 g/L for nZVI and 1.0 g/L for nCaO_(2).These results provide a theoretical basis for the nZVI/nCaO_(2)application to remove DCF in groundwater.展开更多
Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing...Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications.Herein,this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water.Firstly,Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion.The morphological,structural,and compositional evolution of(modified-)nZVI under different environmental conditions,assisted with microscopic and spectroscopic evidence,is then summarized.Afterwards,common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water.Specifically,stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed,emphasizing their capabilities in studying the dynamic iron corrosion processes.Finally,in the future,more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties.We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.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
Nanoscale iron particles （nZVI） is one of the most important engineered nanomaterials applied to environmental pollution control and abatement. Although a multitude of synthesis approaches have been proposed, a faci...Nanoscale iron particles （nZVI） is one of the most important engineered nanomaterials applied to environmental pollution control and abatement. Although a multitude of synthesis approaches have been proposed, a facile method to screen the reactivity of candidate nZVI materials produced using different methods or under varying synthesis conditions has yet been established. In this study, four reaction parameters were adjusted in the preparation of borohydride-reduced nZVI. The reductive properties of the resultant nanoparticles were assayed independently using two model aqueous contaminants, Cu （II） and nitrate. The results confirm that the reductive reactivity of nZVI is most sensitive to the initial concentration of iron precursor, borohydride feed rate, and the loading ratio of borohydride to ferric ion during particle synthesis. Solution mixing speed, in contrast, carries a relative small weight on the reactivity of nZVI. The two probing reactions （i.e., Cu（II） and nitrate reduction） are able to generate consistent and quantitative inference about the mass-normalized surface activity of nZVI. However, the nitrate assay is valid in dilute aqueous solutions only （50 mg.L~ or lower） due to accelerated deactivation of iron surface at elevated nitrate concentra- tions. Additional insights including the structural and chemical makeup of nZVI can be garnered from Cu（II） reduction assessments. The reactivity assays investigated in this study can facilitate screening of candidate materials or optimization of nZVI production parameters, which complement some of the more sophisticated but less chemically specific material characterization methods used in the nZVI research.展开更多
Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale componen...Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale components, an iron （oxyhydr）oxides shell and a metallic iron core. This classical ＂core-shell＂ structure offers nZVI with unique and multifaceted reactivity of sorption, complexation, reduction and precipita- tion due to its strong small particle size for engineering deployment, large surface area, abundant reactive sites and electron-donating capacity for enhanced chemical activity. For over two decades, research has been steadily expanding our understanding on the reaction mechanisms and engineering performance of nZVI for soil and groundwater remediation, and more recently for wastewater treatment.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This study was supported by the State Key Laboratory of Petroleum and Petrochemical Contaminant Control and Treatment,the Open Project(Authorization:PPC2019021)the Research and Promotion Project of Key Technologies for Safety and Environmental Protection of CNPC(2017D-4013)the PetroChina Technology Innovation Fund Research Project(Authorization:2017D-5007-0601,2018D-5007-0605).
文摘Considering the need for efficiently and rapidly treating oily wastewater while preventing secondary pollution,the nanoscale zero-valent iron(nZVI)was supported on biochar prepared by using a spent mushroom substrate(SMS),to produce an iron-carbon composite(SMS-nZVI).The ability of the SMS-nZVI to treat wastewater containing high concentration of oil was then comprehensively evaluated.The morphology,structure,and other properties of the composite were characterized by using scanning electron microscopy,transmission electron microscopy,the Brunauer-Emmett-Teller nitrogen sorption analysis,and the Fourier transform infrared spectroscopy.The results show that the biochar prepared by using the SMS can effectively prevent the agglomeration of nZVI and increase the overall specific surface area,thereby enhancing the absorption of petroleum by the composite.Experiments reveal that compared with the SMS and nZVI,the SMS-nZVI composite removes petroleum faster and more efficiently from wastewater.Under optimized conditions involving an nZVI to biochar mass ratio of 1:5 and a pH value of 4,the efficiency for removal of petroleum from wastewater with an initial petroleum concentration of 1000 mg/L could reach 95%within 5 h.Based on a natural aging treatment involving exposure to air for 30 d,the SMS-nZVI composite retained an oil removal rate of higher than 62%,and this result could highlight its stability for practical applications.
文摘Nano zero valent iron particles (nZVI) are popular the last few years because of the numerous applications in remediation of a wide range of pollutants in contaminated soils and aquifers. The nZVI particles can be 10 - 1000 times more reactive than granular or micro-scale ZVI particles due to the small particle size, large specific surface area and high reactivity. An alternative green synthesis procedure was used for the production of nano zero valent iron particles (nZVI) using green tea (GT) extract, which is characterized by its high antioxidant content. Polyphenols in green tea extract possess double role in the synthesis of nZVI, because they not only reduce ferric cations, but also protect nZVI from oxidation and agglomeration as capping agents. The objective of current study was to simulate ata laboratory scale the attachment of GT-nZVI particles on soil material and study the effectiveness of attached nanoparticles for removing hexavalent chromium (Cr(VI)) from contaminated groundwater flowing through the porous soil bed. Column tests were carried out with various flowrates in order to examine the effect of contact time between the attached on porous medium nZVI and the flow-through solution on Cr(VI) reduction. After the completion of column tests the soil material in each column was split in 5 vertical sections, which were further subjected to chemical analyses and leaching tests. According to the results of the study increasing the contact time favors the reduction and removal of Cr(VI) from the aqueous phase. The reductive precipitation of Cr can be described as a reaction that follows a pseudo-first order kinetic law, with rate constant equal to k = 0.0243 ± 0.0011 min-1. Leaching tests indicated that precipitated chromium is not soluble. In the examined soil material, the total amount of precipitated Cr was found to range between 280 and 890 mg/(kg soil), while soluble Cr was less than 1.4 mg/kg and most probably it was due to the presence of residual Cr(VI) solution in the porosity of soil.
基金the National Natural Science Foundation of China(42077176,41601514)Shanghai“Science and Technology Innovation Action Plan”Project(19230742400,19ZR1459300)+1 种基金Shanghai Peak Discipline Project(0200121005/053,2019010202)State Key Laboratory of Petroleum Pollution Control(PPC2016019)。
文摘Diclofenac(DCF)is one of the most frequently detected pharmaceuticals in groundwater,posing a great threat to the environment and human health due to its toxicity.To mitigate the DCF contamination,experiments on DCF degradation by the combined process of zero-valent iron nanoparticles(nZVI)and nano calcium peroxide(nCaO_(2))were performed.A batch experiment was conducted to examine the influence of the adding dosages of both nZVI and nCaO_(2)nanoparticles and pH value on the DCF removal.In the meantime,the continuous-flow experiment was done to explore the sustainability of the DCF degradation by jointly adding nZVI/nCaO_(2)nanoparticles in the reaction system.The results show that the nZVI/nCaO_(2)can effectively remove the DCF in the batch test with only 0.05 g/L nZVI and 0.2 g/L nCaO_(2)added,resulting in a removal rate of greater than 90%in a 2-hour reaction with an initial pH of 5.The degradation rate of DCF was positively correlated with the dosage of nCaO_(2),and negatively correlated with both nZVI dosage and the initial pH value.The order of significance of the three factors is identified as pH value>nZVI dosage>nCaO_(2)dosage.In the continuous-flow reaction system,the DCF removal rates remained above 75%within 150 minutes at the pH of 5,with the applied dosages of 0.5 g/L for nZVI and 1.0 g/L for nCaO_(2).These results provide a theoretical basis for the nZVI/nCaO_(2)application to remove DCF in groundwater.
基金supported by the National Natural Science Foundation of China (No.52200184)the Fundamental Research Funds for Central Universities (No.12060096014)。
文摘Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron(nZVI)in aquatic environment is particularly significant for understanding the reactivity,longevity and stability of nZVI,as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications.Herein,this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water.Firstly,Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion.The morphological,structural,and compositional evolution of(modified-)nZVI under different environmental conditions,assisted with microscopic and spectroscopic evidence,is then summarized.Afterwards,common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water.Specifically,stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed,emphasizing their capabilities in studying the dynamic iron corrosion processes.Finally,in the future,more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties.We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.
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.
文摘Nanoscale iron particles （nZVI） is one of the most important engineered nanomaterials applied to environmental pollution control and abatement. Although a multitude of synthesis approaches have been proposed, a facile method to screen the reactivity of candidate nZVI materials produced using different methods or under varying synthesis conditions has yet been established. In this study, four reaction parameters were adjusted in the preparation of borohydride-reduced nZVI. The reductive properties of the resultant nanoparticles were assayed independently using two model aqueous contaminants, Cu （II） and nitrate. The results confirm that the reductive reactivity of nZVI is most sensitive to the initial concentration of iron precursor, borohydride feed rate, and the loading ratio of borohydride to ferric ion during particle synthesis. Solution mixing speed, in contrast, carries a relative small weight on the reactivity of nZVI. The two probing reactions （i.e., Cu（II） and nitrate reduction） are able to generate consistent and quantitative inference about the mass-normalized surface activity of nZVI. However, the nitrate assay is valid in dilute aqueous solutions only （50 mg.L~ or lower） due to accelerated deactivation of iron surface at elevated nitrate concentra- tions. Additional insights including the structural and chemical makeup of nZVI can be garnered from Cu（II） reduction assessments. The reactivity assays investigated in this study can facilitate screening of candidate materials or optimization of nZVI production parameters, which complement some of the more sophisticated but less chemically specific material characterization methods used in the nZVI research.
基金supported by the National Natural Science Foundation of China (Nos. 51578398 and 41772243)the National Postdoctoral Program for Innovative Talents (No. BX201700172)
文摘Nanoscale zero-valent iron （nZVI） possesses unique chemistry and capability for the separation and transformation of a growing number of environmental contaminants. A nZVI particle consists of two nanoscale components, an iron （oxyhydr）oxides shell and a metallic iron core. This classical ＂core-shell＂ structure offers nZVI with unique and multifaceted reactivity of sorption, complexation, reduction and precipita- tion due to its strong small particle size for engineering deployment, large surface area, abundant reactive sites and electron-donating capacity for enhanced chemical activity. For over two decades, research has been steadily expanding our understanding on the reaction mechanisms and engineering performance of nZVI for soil and groundwater remediation, and more recently for wastewater treatment.
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。
文摘纳米零价铁材料(nanoscale zero-valent iron,nZVI)是环境领域应用最广泛的纳米材料之一,因其原材料来源丰富、反应产物环境友好,在分离/固定水中重金属方面得到了广泛的研究.实验室研究表明,nZVI能够有效去除复杂实际废水中铜、砷、铅、锌、金等多种重金属,表现出较高的去除负荷.本研究团队在国内首先研究以nZVI技术为核心,开发分离、固定重金属工业废水中重金属的针对性废水处理工艺.构建了废水处理“反应-分离-回用”式纳米零价铁反应器(nano iron reactor,NIR)装置,通过“小试—中试—工程应用”逐级科学放大,将其应用于多种重金属工业废水的处理当中.本文总结了纳米零价铁废水处理工艺,综述了NIR反应器技术处理典型重金属废水的中试和工程应用案例,为nZVI的实际环境应用以及重金属废水处理提供了理论及技术借鉴.
