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

Yu-Hsuan Chiao,Micah Belle Marie Yap Ang,Tanmoy Patra,Rong Fan,S Ranil Wickramasinghe,Shu-Ting Chen,Jorge Almodovar,Wei-Song Hung,David Alfonso Castilla-Casadiego

doi:10.3390/polym12112443

Abstract

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.

Highlights

In recent years, dye removal from textile wastewater is considered as a critical issue because of the potential environmental hazard and associated difficulties in terms of dye recycling [1]
XPS elemental analysis is listed in Table 1, which would verify that the PAA fully covered the polyvinylidene fluoride (PVDF) surface
Chemical characterization confirmed that the PAA chain was successfully grafted and covered on top of the membrane, as evident from the appearance of characteristic peaks of carboxylic acid groups and disappearance of peaks related to –CF2 groups

Summary

Introduction

Dye removal from textile wastewater is considered as a critical issue because of the potential environmental hazard and associated difficulties in terms of dye recycling [1]. Polymers 2020, 12, 2443 such as biological, chemical treatment, and catalytic degradation, were investigated for the dye removal from wastewater [6,7]; the expensive cost and less scale-up possibility are the two factors limiting their application in terms of commercialization. In this context, membrane technology is considered as a promising solution for textile wastewater due to high-quality production without sludge generation and relatively low operational cost compared to the nonphysical separation process. During optimal design of such NF membrane-based processes, one must consider the specific separation mechanism between the membrane and components in the feed

Methods

Results

Conclusion