热处理前溶剂活化对芳香聚酰胺反渗透膜结构的影响机制  

Impact of Solvent Activation Before Heat Treatment on the Structure of Aromatic Polyamide Reverse Osmosis Membrane

作　　者：王志[1,2,3,4] 吴浩文 王纪孝 Wang Zhi;Wu Haowen;Wang Jixiao(School of Chemical Engineering and Technology,Tianjin University,Tianjin 300350,China;Tianjin Key Laboratory of Membrane Science and Desalination Technology,Tianjin 300350,China;State Key Laboratory of Chemical Engineering,Tianjin University,Tianjin 300350,China;Collaborative Innovation Center of Chemical Science and Engineering(Tianjin),Tianjin 300350,China)

机构地区：[1]天津大学化工学院,天津300350 [2]天津市膜科学与海水淡化技术重点实验室,天津300350 [3]化学工程联合国家重点实验室(天津大学),天津300350 [4]天津化学化工协同创新中心,天津300350

出　　处：《天津大学学报（自然科学与工程技术版）》2023年第6期553-563,共11页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金重点资助项目(U2006220).

摘　　要：热处理前对芳香聚酰胺反渗透膜进行溶剂活化(或称润洗)是一类提高膜透过性的手段.普遍认为,在热处理前溶剂活化的过程中,芳香聚酰胺层内残留的芳香聚酰胺低聚物将溶于溶剂且溶剂可溶胀重整聚酰胺层,因而膜结构与性能发生变化.然而,热处理前溶剂活化多使用非极性溶剂,这类溶剂与芳香聚酰胺的溶解度参数相差较大,对芳香聚酰胺层的溶胀与溶解作用均较弱,因此,热处理前溶剂活化引起的膜结构改变不能完全归因于非极性溶剂与膜的相互作用.近期有研究表明,芳香聚酰胺层内残留物可在水中溶出,推测热处理前溶剂活化可能通过影响残留物在水中的溶出而改变膜结构.基于此,进一步探究热处理前溶剂活化对膜结构的影响机制.对比了水浸泡前后的膜结构与性能,分析了活化膜与未活化膜在水中溶出物质的紫外-可见光谱,对比了未活化膜和活化膜的结构与性能.结果表明,热处理后芳香聚酰胺层内仍有大量易溶于水的亲水性残留物.热处理前利用正己烷对膜进行溶剂活化可除去未反应单体及低聚物,削弱热处理过程中聚酰胺层的进一步交联,加剧芳香聚酰胺层内亲水性残留物在水中的溶出.因此,活化后的膜分离层厚度、粗糙度和分离层内酰胺含量均降低,膜透过性提升.本工作完善了热处理前溶剂活化对膜结构的影响机制.Solvent activation or solvent rinse of aromatic polyamide reverse osmosis membrane before heat treatment typically improves membrane permeance.Generally,during solvent activation before heat treatment,the residual polyamide oligomers in the polyamide layer dissolve in the solvent,which can swell and rearrange the polyamide layer,thus changing the structure and performance of the membrane.However,the solvent used for solvent activation before heat treatment is typically a non-polar solvent whose solubility parameter is substantially different from aromatic polyamide.Consequently,the swelling and dissolution of the aromatic polyamide layer should be weak with these non-polar solvents;thus,the change in the membrane structure caused by solvent activation before heat treatment cannot be completely attributed to the interaction between the non-polar solvent and membrane.Recent studies have shown that residues in the aromatic polyamide layer can be dissolved in water.The solvent activation before heat treatment may affect the dissolution of residues in water and later change the structure of the membrane.To further explore how solvent activation before heat treatment affects the membrane structure and properties,the cases before and after water immersion were compared.The ultraviolet-visible spectra of the substances dissolved in water from the activated and inactivated membranes were analyzed,and their structures and properties were compared.The results indicate that numerous water-soluble hydrophilic residues remained in the aromatic polyamide layer after heat treatment.Solvent activation of the membrane with hexane before heat treatment removed unreacted monomers and oligomers,weakening further the cross-linking of the polyamide layer during the heat treatment and accelerating the dissolution of residues in the aromatic polyamide layer in water.Therefore,the thickness,roughness,and polyamide content of the separation layer of the activated membrane are reduced,and the membrane permeance is improved.In this study,the

关 键 词：反渗透膜 芳香聚酰胺 溶剂活化 热处理 

分 类 号：TQ028.8[化学工程]