Rapid and eco-friendly technique for surface modification of TFC RO membrane for improved filtration performance

Date

2021-06-01

Author

Khoo, Ying Siew
Lau, Woei Jye
Liang, Yong Yeow
Karaman, Mustafa
Gürsoy, Mehmet
Lai, Gwo Sung
Ismail, Ahmad Fauzi

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In this work, an environmentally friendly plasma enhanced chemical vapor deposition (PECVD) technique was employed to rapidly alter the surface properties of commercial thin film composite extra-low energy (XLE) reverse osmosis (RO) membrane to improve its fouling resistance and desalination performance. Hereafter, two different hydrophilic precursors, i.e., aniline monomer and oxygen (O-2) gas were respectively introduced to the membrane's polyamide surface at different plasma treatment duration (15 s and 60 s). At 15-s plasma treatment, our results revealed that the O2-modified membrane outperformed the polyaniline (PANI)-modified membrane and unmodified membrane, attributed to the polar functional groups presented on the polyamide surface. Compared to plasma polymerization of aniline, O-2 plasma etching can lower polyamide densification degree which potentially reduce membrane resistance. Evidently, the O-2-modified membrane exhibited higher pure water permeability (6.64 L/m(2).h.bar) compared to the PANI-modified membrane (5.57 L/m(2).h.bar). The enhanced surface hydrophilicity of O-2-modified membrane could be noticed when its water contact angle was reduced from 88.39 degrees (unmodified) to 79.46 degrees in just 15-s plasma treatment. Furthermore, this O-2-modified membrane achieved an outstanding NaCl and Na2SO4 rejection with an increment of 4.2% and 2.6%, respectively compared to the unmodified membrane. However, prolonged gas plasma treatment (60 s) should be avoided as it can damage polyamide selective layer. With respect to fouling resistance, the best O-2-modified membrane demonstrated higher flux recovery rate (96%) than that of unmodified membrane (76.5%) after being used to filter 1000-ppm sodium alginate solution. These results highlighted the versatility of O-2 plasma treatment to improve RO membrane performance.

URI

https://hdl.handle.net/11511/116315

Collections

Department of Metallurgical and Materials Engineering, Article