Pressure-assisted polydopamine modification of thin-film composite reverse osmosis membranes for enhanced desalination and antifouling performance

• Published in: Desalination 2022-05, Vol.530, p.115671, Article 115671
• Main Authors: Zhao, Die Ling, Zhao, Qipeng, Lin, Hongjun, Chen, Shing Bor, Chung, Tai-Shung
• Format: Article
• Language: English
• Subjects: Antifouling; Desalination; Polydopamine (PDA); Reverse osmosis (RO); Thin-film composite (TFC)
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2022.115671

Polydopamine (PDA) has been widely used to modify membrane surface with the aims to tune its hydrophilicity and to mitigate its fouling propensity. However, modifications at ambient pressure only occur on the membrane surface and often result in a drop in water permeance, and sometimes also salt rejection. In this work, a pressure-assisted coating method was employed to overcome the aforementioned drawbacks by tuning the inner structure of membranes with the aid of applying a hydraulic pressure during the PDA modification. The coating pressure and duration were varied to investigate their effects on water flux and NaCl rejection as well as surface microstructure. After coating with PDA under 2 bar for 3 h, the water permeance and salt rejection of the resultant membranes were respectively enhanced to 3.31 LMH/bar and 98.95%. Simultaneously, the PDA-modified membranes exhibited excellent antifouling behavior upon the exposure to alginate sodium. Thus, the overall desalination performance of TFC membranes is effectively promoted by the newly developed PDA coating method for water treatment and reuse. •Modifications of TFC membranes by polydopamine under hydraulic pressure are investigated.•The changes in inner structure of TFC layer help improve the water permeance and salt rejection.•The PDA-modified membranes also exhibit excellent rejection to boron and antifouling behavior.