Facile Surface Modification of Polyamide Membranes Using UV-Photooxidation Improves Permeability and Reduces Natural Organic Matter Fouling

Hojung Rho, Sung Ju Im, Omar Alrehaili, Sungyun Lee, Am Jang, François Perreault, Paul Westerhoff

Research output: Contribution to journalArticlepeer-review

Abstract

A new optimized ultraviolet (UV) technique induced a photooxidation surface modification on thin-film composite (TFC) polyamide (PA) brackish water reverse osmosis (BWRO) membranes that improved membrane performance (i.e., permeability and organic fouling propensity). Commercial PA membranes were irradiated with UV-B light (285 nm), and the changes in the membrane performance were assessed through dead-end and cross-flow tests. UV-B irradiation at 12 J·cm-2 enhanced the pure water permeability by 34% in the dead-end tests without decreasing the mono- or divalent ion rejections, as compared with the pristine PA membrane, and led to less fouling by natural organic matter in the cross-flow tests. Scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) confirmed that UV-B irradiation opened the pore structure and created carboxylic and amine groups on the PA surface, leading to increased membrane surface charge and hydrophilicity. Thus, an optimal UV-B dose appears to modify only a thin layer of the PA membrane surface, which favorably enhances the membrane performance. UV-B did not alter the structure, flux, or salt rejection for cellulose triacetate (CTA)-based membranes. While other membrane surface modifications include oxidants, strong acids, and bases, the UV-B facile treatment is chemical-free, thus reducing chemical wastes, and easy to apply in roll-to-roll fabrication processes of PA membranes. The results also showed that a low UV irradiation dose could be applied to PA or CTA membranes for disinfection or photocatalytic oxidation.

Original languageEnglish (US)
JournalEnvironmental Science and Technology
Volume55
Issue number10
DOIs
StatePublished - May 18 2021

Keywords

  • desalination
  • fouling
  • membrane
  • ultraviolet
  • water treatment

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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