High-Performance Polyacrylic Acid-Grafted PVDF Nanofiltration Membrane with Good Antifouling Property for the Textile Industry

• Main Authors: Yu-Hsuan Chiao, Shu-Ting Chen, Micah Belle Marie Yap Ang, Tanmoy Patra, David Alfonso Castilla-Casadiego, Rong Fan, Jorge Almodovar, Wei-Song Hung, S. Ranil Wickramasinghe
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Polymers
• Subjects: poly-(acrylic acid); loose nanofiltration; UV-grating; dye removal; superoleophobic
• Online Access: https://www.mdpi.com/2073-4360/12/11/2443

In the textile industry, a high-efficiency dye removal and low-retention of salt is demanded for recycling wastewater. In this study, polyvinylidene fluoride (PVDF) ultrafiltration membrane was transformed to a negatively charged loose nanofiltration (NF) membrane through UV-grafting of acrylic acid. At the optimal exposure of PVDF membrane in UV light for 5 min, the membrane had a high dye recovery above 99% (Congo red and Eriochrome^® Black T) and a low sodium chloride (NaCl) rejection of less than 15% along with pure water flux of 26 L∙m⁻²∙h⁻¹∙bar⁻¹. Its antifouling and oleophobicity surface properties were verified using fluorescent- bovine serum albumin (BSA) and underwater mineral oil contact angle, respectively. According to the fluorescent microscopic images, the modified membrane had ten times lower adhesion of protein on the surface than the unmodified membrane. The underwater oil contact angle was raised from 110° to 155°. Moreover, the salt rejection followed this sequence: Na₂SO₄ > MgSO₄ > NaCl > MgCl₂, which agreed with the typical negatively charged NF membrane. In addition, the physicochemical characterization of membranes was further investigated to understand and link to the membrane performance, such as surface functional group, surface elements analysis, surface roughness/morphology, and surface hydrophilicity.