Adsorption mechanisms of PFOA onto activated carbon anchored with quaternary ammonium/epoxide-forming compounds: A combination of experiment and model studies  

作　　者：Chen Yuan Yang Huang Fred SCannon Zhiwei Zhao 

机构地区：[1]Shenzhen Academy of Environmental Science,Shenzhen 518001,China [2]College of Urban Construction and Environmental Engineering,Chongqing University,Chongqing 400045,China [3]Department of Civil and Environmental Engineering,Pennsylvania State University,University Park,PA 16802,USA [4]College of Resources and Environment,Chengdu University of Information Technology,Chengdu 610225,China

出　　处：《Journal of Environmental Sciences》2020年第12期94-102,共9页环境科学学报（英文版）

基　　金：funding from Evoqua Company;the National Natural Science Foundation of China (Nos. 51878090 and 51808066);the Chinese Scholarship Council for financial support。

摘　　要：When wood-based activated carbon was tailored with quaternary ammonium/epoxide(QAE) forming compounds(QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid(PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before halfbreakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.

关 键 词：Perfluorooctanoic acid NITRATE Carbon Atomistic model Adsorption mechanism 

分 类 号：X523[环境科学与工程—环境工程] TQ424.1[化学工程]