GO-PTFE复合膜强化膜蒸馏深度处理焦化废水
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摘要
为了提高膜的抗污染抗润湿性能,采用表面涂覆法将氧化石墨烯(GO)结合在聚四氟乙烯(PTFE)膜表面,制备亲水-疏水复合膜用于膜蒸馏深度处理焦化废水,并对比了改性复合膜与未改性原膜的表面特性和膜蒸馏效果,分析了GO表面改性对膜蒸馏效果的强化机制。结果表明,膜表面经过GO改性后接触角由144.2°下降至103.9°,且表面出现羟基、羧基等亲水性官能团,说明膜表面亲水改性成功。GO-PTFE复合膜相比原膜通量提高了36.6%,产水电导率保持在25μS/cm,出水的荧光峰强度明显减弱,说明GO-PTFE复合膜能有效截留焦化废水中的无机盐和有机物,相比原膜的抗污染抗润湿性能显著提高。这种强化过程主要归因于GO良好的亲水性、导热性和特有的纳米孔道对污染物的截留效应。
In order to improve the membrane resistance to fouling and wetting, a novel hydrophilic-hydrophobic composite membrane was fabricated by coating graphene oxide(GO) on the polytetrafluoroethylene(PTFE) substrate. The prepared membrane was used for advanced treatment of coking wastewater in membrane distillation(MD), the surface characteristics and MD performance of modified and un-modified membrane were compared, and the enhancement mechanism of GO surface modification to MD performance was analyzed. Results showed that the water contact angle of membrane decreased from 144.2° to 103.9° after GO surface modification, hydrophilic functional groups such as hydroxyl and carboxyl were detected on the surface of composite membrane, indicating hydrophilic modification of membrane surface was successful. The permeate flux of GO/PTFE composite membrane increased 36.6% compared with original membrane, the permeate conductivity maintained at 25 μS/cm, and without significant fluorescence peaks detected in the distillate.This demonstrated the GO/PTFE composite membrane could effectively reject salts and organics in coking wastewater, the membrane resistance to fouling and wetting improved significantly compared to original membrane, which might be ascribed to the presence of hydrophilic functional groups, higher thermal conductivity and nanocapillary for pollutant rejection.
In order to improve the membrane resistance to fouling and wetting, a novel hydrophilic-hydrophobic composite membrane was fabricated by coating graphene oxide(GO) on the polytetrafluoroethylene(PTFE) substrate. The prepared membrane was used for advanced treatment of coking wastewater in membrane distillation(MD), the surface characteristics and MD performance of modified and un-modified membrane were compared, and the enhancement mechanism of GO surface modification to MD performance was analyzed. Results showed that the water contact angle of membrane decreased from 144.2° to 103.9° after GO surface modification, hydrophilic functional groups such as hydroxyl and carboxyl were detected on the surface of composite membrane, indicating hydrophilic modification of membrane surface was successful. The permeate flux of GO/PTFE composite membrane increased 36.6% compared with original membrane, the permeate conductivity maintained at 25 μS/cm, and without significant fluorescence peaks detected in the distillate.This demonstrated the GO/PTFE composite membrane could effectively reject salts and organics in coking wastewater, the membrane resistance to fouling and wetting improved significantly compared to original membrane, which might be ascribed to the presence of hydrophilic functional groups, higher thermal conductivity and nanocapillary for pollutant rejection.
引文
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[3]XU L,WANG J,ZHANG X,et al.Development of a novel integrated membrane system incorpo-rated with an activated coke adsorption unit for advanced coal gasification wastewater treat-ment[J].Colloids&Surfaces A Physicochemical&Engineering Aspects,2015,484:99-107.
[4]WIJEKOON K C,HAI F I,KANG J,et al.Rejection and fate of trace organic compounds(Tr OCs)during membrane distillation[J].Journal of Membrane Science,2014,453(3):636-642.
[5]LI J,WU J,SUN H,et al.Advanced treatment of biologically treated coking wastewater by mem-brane distillation coupled with precoagulation[J].Desalination,2016,380:43-51.
[6]REN J,LI J,CHEN Z,et al.Fate and wetting potential of biorefractory organics in membrane distillation for coke wastewater treatment[J].Chemosphere,2018,208:450.
[7]SALEHI S M,PROFIO G D,FONTANANOVA E,et al.Membrane distillation by novel hydrogel composite membranes[J].Journal of Membrane Science,2016,504:220-229.
[8]李英,高云霄,李保安.膜蒸馏用PVDF抗复合污染膜的制备与测试[J].化学工业与工程,2016,33(6):49-55.
[9]HU M,MI B.Enabling graphene oxide nanosheets as water separation mem-branes[J].Environmental Science&Technology,2013,47(8):3715-3723.
[10]WANG K,HOU D,WANG J,et al.Hydrophilic surface coating on hydrophobic PTFE membrane for robust anti-oil-fouling membrane distillation[J].Applied Surface Science,2018,450:57-60.
[11]ZHANG J,XUE Q,PAN X,et al.Graphene oxide/polyacrylonitrile fiber hierarchical-structured membrane for ultra-fast microfiltration of oil-water emulsion[J].Chemical Engineering Journal,2017,307:643-649.
[12]杨鸿鹰,张文存,高小媛,等.氧化石墨烯薄膜的制备及其在水处理应用中的研究进展[J].应用化工,2016,45(4):760-764.
[13]代婷,武春瑞,吕晓龙,等.典型污染物对膜蒸馏过程膜污染的影响[J].水处理技术,2012,38(8):9-14.
[14]HUANG Y X,WANG Z,JIN J,et al.A novel janus membrane for membrane distillation with simul-taneous fouling and wetting resistance[J].Environmental Science&Technology,2017,51(22):13304.
[15]贺润升,徐荣华,韦朝海.焦化废水生物出水溶解性有机物特性光谱表征[J].环境化学,2015(1):129-136.
[16]OU H S,WEI C H,MO C H,et al.Novel insights into anoxic/aerobic(1)/aerobic(2)biological flu-idized-bed system for coke wastewater treatment by fluorescence excitation-emission matrix spectra coupled with parallel factor analysis.[J].Chemosphere,2014,113:158-164.
[17]WANG Z,LIN S.Membrane fouling and wetting in membrane distillation and their mitigation by novel membranes with special wettability.[J].Water Research,2017,112:38-47.
[18]LEAPER S,ABDEL-KARIM A,FAKI B,et al.Flux-enhanced PVDFmixed matrix membranes in-corporating APTS-functionalized graphene oxide for membrane distillation[J].Journal of Membrane Science,2018,554.
[19]张飞龙,王莉,俞树荣,等.氧化石墨烯及其导热纳米流体的制备与性能[J].功能材料,2015,46(16):16138-16141.