碱化反应对乙二胺功能化氧化石墨烯纳滤膜离子分离效率的提升研究  

IMPROVEMENT OF ION SIEVING IN ETHYLENEDIAMINE-MODIFIED GRAPHENE OXIDE MEMBRANES ENABLED BY ALKALINIZATION

作　　者：雷丝雨 张文彬[1] 张炜铭[1] LEI Siyu;ZHANG Wenbin;ZHANG Weiming(State Key Laboratory of Pollution Control and Resource Reuse,School of the Environment,Nanjing University,Nanjing 210023,China)

机构地区：[1]污染控制和资源化研究国家重点实验室,环境学院,南京大学,南京210023

出　　处：《离子交换与吸附》2022年第3期205-216,共12页Ion Exchange and Adsorption

基　　金：国家重点研发计划(2021YFA1201703)。

摘　　要：氧化石墨烯(GO)膜具有层状亚纳米通道,适用于尺寸依赖的污染物分子筛分;其中,通过交联来稳定层间距是防止其溶胀、保障其对目标污染物去除的重要途径之一。乙二胺是常用的交联剂,但乙二胺改性后氧化石墨烯膜表面亲水性变弱、水通量降低。本研究通过碱化的方式,将氧化石墨烯膜边缘经乙二胺改性后形成的酰胺结构以及未反应的羧基转化为亲水性更强的羧酸根离子,促进水分子进入层间通道,从而大幅度提高了膜的亲水性。碱化后的乙二胺功能化氧化石墨烯膜(rbGO/PVDF)瞬间水接触角从(59±1.3)°减小到(17±0.2)°,亲水性显著提高;FT-IR与XPS分析表明,rbGO/PVDF膜中羧酸根离子(―COO~-)含量从0.8%增加至7.6%,乙二胺与羧基形成的酰胺结构被破坏;相应的,碱化后的膜水通量高达(307.0±11.0)L/(m^(2)·h),是碱化前的44倍。以络合态重金属Cu-EDTA为目标污染物,rbGO/PVDF膜展现出较高的去除能力,具有深度去除工业废水中重金属络合物的潜力。Graphene oxide(GO) membranes with layered sub-nanochannels are ideal 2D materials for size-dependent molecular screening. The crosslinking strategy is one of key approaches to stabilize layer spacing to prevent membrane swelling and ensure the removal of the target contaminants. Ethylene diamine(EDA), commonly used as the cross-linking agent for GO membrane modification, always decreases the surface hydrophilicity and water flux. In this study, alkalinization was utilized to convert the amide structure(formed by EDA modification)at the edge of graphene oxide membranes along with unreacted carboxyl groups into more hydrophilic carboxylate ions, which was proved to be efficient in promoting water molecules entering the interlayer channels and thus improving the hydrophilicity of GO membranes. The water contact angle of alkalinized EDA-functionalized graphene oxide membrane(rbGO/PVDF)decreased from(59±1.3)° to(17±0.2)°, indicating the significantly improved hydrophilicity of rbGO/PVDF membrane. In addition, FT-IR and XPS characterizations both demonstrated the carboxylate ion(―COO) contents in the rbGO/PVDF membrane increased from 0.8% to 7.6%,suggesting the destruction of amide structure. A fast and selective water permeation was observed through separation of Cu-EDTAfrom water, with the permeance of(307.0±11.0)L/(m^(2)·h),nearly 44 times higher than that of the control pristine GO membranes, suggesting the great potential in deep removal of heavy metal complexes in industrial wastewater.

关 键 词：氧化石墨烯复合膜 化学交联 碱化改性 亲水性 

分 类 号：X703[环境科学与工程—环境工程]