The coupling of zero-valent iron(ZVI)with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater.However,the uniform activation of ZVI throughout the column and t...The coupling of zero-valent iron(ZVI)with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater.However,the uniform activation of ZVI throughout the column and the proportional removal of target contaminants are urgently required for the prevention of premature filter clogging and the extension of the effective column operational time.In this study,we successfully achieved this objective by simply doping granular sand with ZVI at appropriate weight ratios.When pure ZVI packed column was spiked with oxidants,the majority of As trapping occurred between the column inlet and the first sampling point.In a packed column with a 1:20 mixture of ZVI and sand,the average As removal efficiency was 36(1st),13.1(2nd),18.5(3rd),19.2(4th)and 5.9%(5th outlet).The overall arsenic removal performance of the composite filling system of ZVI/sand was equally as efficient as that of the previous pure ZVI-packed system.Moreover,the leaching of Fe was significantly reduced with an increased sand ratio,resulting in clearer water with less turbidity.The results of X-ray photoelectron spectroscopy(XPS)demonstrated that more than 54%of the arsenic was reduced to As(III).X-ray diffraction(XRD)and scanning electron microscopy(SEM)confirmed the extensive corrosion of the ZVI surface,which resulted in various species of iron oxyhydroxides responsible for the highly efficient sequester of arsenic through reduction,adsorption,and coprecipitation.展开更多
Arsenic(As)is recognized as a persistent and toxic contaminant in the environment that is harmful to humans.Biochar,a porous carbonaceous material with tunable functionality,has been used widely as an adsorbent for re...Arsenic(As)is recognized as a persistent and toxic contaminant in the environment that is harmful to humans.Biochar,a porous carbonaceous material with tunable functionality,has been used widely as an adsorbent for remediating As-contaminated water and soils.Several types of pristine and modified biochar are available,and significant efforts have been made toward modifying the surface of biochars to increase their adsorption capacity for As.Adsorption capacity is influenced by multiple factors,including biomass pyrolysis temperature,pH,the presence of dissolved organic carbon,surface charge,and the presence of phosphate,silicate,sulfate,and microbial activity.Improved As adsorption in modified biochars is attributed to several mechanisms including surface complexation/precipitation,ion exchange,oxidation,reduction,electrostatic interactions,and surface functional groups that have a relatively higher affinity for As.Modified biochars show promise for As adsorption;however,further research is required to improve the performance of these materials.For example,modified biochars must be eco-friendly,cost-effective,reliable,efficient,and sustainable to ensure their widespread application for immobilizing As in contaminated water and soils.Conducting relevant research to address these issues relies on a thorough understanding of biochar modifications to date.This study presents an in-depth review of pristine and modified biochars,including their production,physicochemical properties,and As adsorption mechanisms.Furthermore,a comprehensive evaluation of biochar applications is provided in As-contaminated environments as a guide for selecting suitable biochars for As removal in the field.展开更多
基金Authors greatly acknowledge the support from the National Natural Science Foundation of China(Grant No.21876011)National Key Research and Development Program of China(Grant No.2017YFA0605001)Fund for Innovative Research Group of the National Natural Science Foundation of China(Grant No.51721093).
文摘The coupling of zero-valent iron(ZVI)with common oxidants has recently achieved very rapid and highly efficient removal of Heavy metals from wastewater.However,the uniform activation of ZVI throughout the column and the proportional removal of target contaminants are urgently required for the prevention of premature filter clogging and the extension of the effective column operational time.In this study,we successfully achieved this objective by simply doping granular sand with ZVI at appropriate weight ratios.When pure ZVI packed column was spiked with oxidants,the majority of As trapping occurred between the column inlet and the first sampling point.In a packed column with a 1:20 mixture of ZVI and sand,the average As removal efficiency was 36(1st),13.1(2nd),18.5(3rd),19.2(4th)and 5.9%(5th outlet).The overall arsenic removal performance of the composite filling system of ZVI/sand was equally as efficient as that of the previous pure ZVI-packed system.Moreover,the leaching of Fe was significantly reduced with an increased sand ratio,resulting in clearer water with less turbidity.The results of X-ray photoelectron spectroscopy(XPS)demonstrated that more than 54%of the arsenic was reduced to As(III).X-ray diffraction(XRD)and scanning electron microscopy(SEM)confirmed the extensive corrosion of the ZVI surface,which resulted in various species of iron oxyhydroxides responsible for the highly efficient sequester of arsenic through reduction,adsorption,and coprecipitation.
基金the Cooperative Research Program for Agriculture Science and Technology Development(PJ01475801)from Rural Development Administrationthe Republic of Korea,the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(2021R1A2C2011734)+2 种基金Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(NRF-2021R1A6A1A10045235)the National Natural Science Foundation of China(21876180)the Outstanding Youth Project of Guangdong Natural Science Foundation(2022B1515020030).
文摘Arsenic(As)is recognized as a persistent and toxic contaminant in the environment that is harmful to humans.Biochar,a porous carbonaceous material with tunable functionality,has been used widely as an adsorbent for remediating As-contaminated water and soils.Several types of pristine and modified biochar are available,and significant efforts have been made toward modifying the surface of biochars to increase their adsorption capacity for As.Adsorption capacity is influenced by multiple factors,including biomass pyrolysis temperature,pH,the presence of dissolved organic carbon,surface charge,and the presence of phosphate,silicate,sulfate,and microbial activity.Improved As adsorption in modified biochars is attributed to several mechanisms including surface complexation/precipitation,ion exchange,oxidation,reduction,electrostatic interactions,and surface functional groups that have a relatively higher affinity for As.Modified biochars show promise for As adsorption;however,further research is required to improve the performance of these materials.For example,modified biochars must be eco-friendly,cost-effective,reliable,efficient,and sustainable to ensure their widespread application for immobilizing As in contaminated water and soils.Conducting relevant research to address these issues relies on a thorough understanding of biochar modifications to date.This study presents an in-depth review of pristine and modified biochars,including their production,physicochemical properties,and As adsorption mechanisms.Furthermore,a comprehensive evaluation of biochar applications is provided in As-contaminated environments as a guide for selecting suitable biochars for As removal in the field.
