Self-cleaning and antifouling properties of plasma-grafted poly(vinylidene fluoride) membrane coated with ZnO for water treatment

Fouling is the main drawback in using membranes for water purification. This study focused on the investigation of coating ZnO onto the poly (vinylidene fluoride) (PVDF) membranes in order to alleviate fouling through the photooxidation process. Poly (acrylic acid) (PAA) was plasma-grafted on the PVDF to introduce functional groups on the membrane surface to support the adhering catalyst. ZnO particles were synthesized by co-precipitation of zinc acetate with oxalic acid at 60 degrees C. The synthesized ZnO was loaded on the membrane surface at varying dope concentrations (0.5, 1.5 and 3.0 wt% Zn0). Results showed that the membrane hydrophilicity was tremendously enhanced by the self-assembly of ZnO and the highest water flux was found at 0.5% ZnO. The membranes were then severely fouled on filtration of alginate (1 wt%) and the ZnO-coated membranes were able to fully recover their original fluxes upon UV irradiation for 30 min. Furthermore, the modified membranes exhibited excellent photocatalytic activity, wherein PVDF-g-PAA/ZnO-3% membrane could decolorize 86% of remazol black B under UV irradiation of 5 h. This indicates that PVDF-g-PAA/ZnO has a potential application in water treatment with its combined advantage of membrane filtration and photocatalytic oxidation to minimize membrane fouling and improve reusability of ZnO. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.