Efficient reduction and adsorption of Cr(Ⅵ)using FeCl_(3)-modified biochar:Synergistic roles of persistent free radicals and Fe(Ⅱ)  

作　　者：Shujie Hu Chengshuai Liu Hongling Bu Manjia Chen Ying-heng Fei 

机构地区：[1]National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China,Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management,Institute of Eco-environmental and Soil Sciences,Guangdong Academy of Sciences,Guangzhou 510650,China [2]State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Science,Guiyang 550081,China [3]School of Environment Science and Engineering,Guangzhou University,Guangzhou 510006,China [4]College of Resources and Environment,Chongqing School,University of Chinese Academy of Sciences,Chongqing 400714,China [5]School of Environmental Science and Engineering,Guangdong University of Technology,Guangzhou 510006,China

出　　处：《Journal of Environmental Sciences》2024年第3期626-638,共13页环境科学学报（英文版）

基　　金：supported by the National Key Research and Development Program of China (No.2020YFC1808500);the National Natural Science Foundation of China (Nos.42107046 and 41907119);the GDAS’Project of Science and Technology Development (Nos.2022GDASZH-2022010105,and 2019GDASYL-0102002-5);the Postdoctoral Science Foundation of China (No.2020M682634);the Guangdong Basic and Applied Basic Research Foundation (No.2021A1515011540)。

摘　　要：Transition metal iron and persistent free radicals(PFRs)both affect the redox properties of biochar,but the electron transfer relationship between them and the coupling reduction mechanism of Cr(Ⅵ)requires further investigation.To untangle the interplay between iron and PFRs in biochar and the infuences on redox properties,FeCl_(3)-modified rice husk biochar(FBCs)was prepared and its reduction mechanism for Cr(Ⅵ)without light was evaluated.The FBCs had higher surface positive charges,oxygen-containing functional groups,and PFRs compared with pristine rice husk biochar(BC).Phenoxyl PFRs with high electrondonating capability formed in biochar.The pronounced electron paramagnetic resonance signals showed that the PFRs preferred to form at lower Fe(Ⅲ)concentrations.While a high concentration of Fe(Ⅲ)would be reduced to Fe(Ⅱ)and consumed the formed PFRs.Adsorption kinetics and X-ray photoelectron spectroscopy analysis indicated that the FBCs effectively enhanced the Cr(Ⅵ)removal efficiency by 1.54-8.20 fold and the Cr(Ⅵ)reduction efficiency by 1.88-9.29 fold compared to those of BC.PFRs quenching and competitive reductant addition experiments revealed that the higher Cr(Ⅵ)reduction performance of FBCs was mainly attributed to the formed PFRs,which could contribute to~74.0%of Cr(Ⅵ)reduction by direct or indirect electron transfer.The PFRs on FBCs surfaces could promote the Fe(Ⅲ)/Fe(Ⅱ)cycle through single electron transfer and synergistically accelerate~52.3%of Cr(Ⅵ)reduction.This study provides an improved understanding of the reduction mechanism of iron-modified biochar PFRs on Cr(Ⅵ)in environments.

关 键 词：BIOCHAR Iron-modification Cr(Ⅵ) Electron transfer Reduction mechanism 

分 类 号：X505[环境科学与工程—环境工程] TQ424[化学工程]