膜科学与技术

PDA与PEI共沉积和分步沉积方法对纳滤膜性能的影响

作者：苏婉，张文娟，张宇峰

单位： 1 天津城建大学水质科学与技术天津市重点实验室，天津 300384；2 天津工业大学省部共建分离膜与膜过程国家重点实验室，天津 300387

关键词：聚多巴胺；聚乙烯亚胺；共沉积；分步沉积

出版年,卷(期):页码： 2020,40(3):14-21

摘要：

本研究通过采用聚多巴胺（PDA）与聚乙烯亚胺（PEI）共沉积和分步沉积两种方法对聚砜（PSf）基膜进行改性，对比两种方法改性后纳滤膜性能的差异。研究中对改性前后膜的接触角、通量、截留率及稳定性进行了测试，并通过SEM、AFM、ATR-FTIR、XPS等方法对改性前后膜表面形貌结构、官能团种类、元素组成等进行表征。结果表明，改性时间为8h时，PDA与PEI分步沉积改性后的膜接触角为49.85°，小于共沉积的68.55°；对MgSO4的截留率为95.2%，高于共沉积改性后的83.0%，但分步沉积对膜通量的影响更大。连续七天的过滤实验表明两种方法改性后的纳滤膜的盐渗透通量和截留率具有长期稳定性。Zeta电位显示两种沉积方法均使膜表面电负性降低。膜表面表征表明两种方法均能使PDA与PEI交联涂层牢牢粘附在PSf基膜上，但两种改性方法的反应机理有所不同：PDA/PEI共沉积更易发生Schiff base反应，而分步沉积法更倾向于发生Michael addition反应。研究结果对于不同功能改性膜的发展提供理论基础，为PSf膜表面改性提供参考依据。

In this study, polydopamine（PDA）and polyethylenimine（PEI）co-deposition and step deposition were used to modify the polysulfone (PSf) membrane, and the performance differences of the modified nanofiltration (NF) membrane were compared. The contact angle, flux, rejection, and stability of the modified membranes were tested. The surface morphology, functional groups and element composition of the modified membranes were characterized by SEM, AFM, ATR-FTIR and XPS, etc. The results showed that after modification for 8 h, the contact angle of PDA and PEI step deposition modified membrane was 49.85°, less than 68.55° of the membrane with PDA/PEI co-deposition. The rejection of MgSO4 was 95.2%, which is higher than 83.0% of the co-deposition, but step deposition had a greater impact on membrane flux. The continuous filtration experiments for seven days showed that the salt permeation flux and rejection rate of the modified NF membranes by the two methods had long-term stability. The Zeta potential showed that both deposition methods caused the membrane surface potential becoming less negative. The characterization of the membranes showed that both methods could make PDA and PEI cross-linked coatings stick firmly to PSf base membrane, but the reaction mechanisms of the two modification methods are different: PDA/PEI co-deposition was more inclined to Schiff base reaction, while step deposition method was more prone to Michael addition reaction. The results provide a theoretical basis for the development of different functional modified membranes and a reference for the surface modification of PSf membranes.

第一作者简介：苏婉（1996-），女，河南平舆人，硕士，主要从事方向为膜材料与膜改性方面的研究，E-mail: 2587103926@qq.com. *通讯作者，E-mail: wenjuanvivian@126.com, zyf9182@163.com

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