Preparation and Characterization of Antifouling Mixed Matrix Ultra filtration Membranes Tailored by UiO-66 and Zeolite 4A for the Removal of Humic Acid

Abstract

Polysulfone (PSf) has intrinsic hydrophobic nature which makes it prone to organic fouling due to the occurrence of organic matter present in water. In this study, in order to prepare antifouling Mixed Matrix Membranes (MMMs), two kinds of porous fillers; UiO-66 and Zeolite 4A and their combination (Zeolite4A@UiO-66) are incorporated in PSf matrix with different loadings (0.5 wt%, 1 wt%, 2 wt%). All membranes were prepared by phase inversion technique. The complimentary effects of nanofillers were investigated on membrane morphology and performance;pure water flux, humic acid rejection, static humic acid adsorption and antifouling properties i.e. Relative Flux Reduction (RFR) and Flux Recovery Ratio (FRR). The morphological characteristics of membranes were investigated with Atomic Force Microscopy (AFM) which showed that all MMMs possessed lower roughness as compared to neat PSf membrane. SEM cross section of membranes confirmed that all MMMs possessed wider macrovoids with high nanofiller loadings as compared to neat PSf membrane. According to surface morphology of membranes, all MMMs are prone to agglomeration with high nanofiller loadings and membranes with combine fillers (Zeolite4A@UiO-66) showed more tendency of agglomeration than single filler membranes. Water contact angle results showed that all MMMs exhibited better hydrophilicity than neat PSf membrane and therefore possessed low static humic acid adsorption than neat PSf membrane. All MMMs except Zeolite4A@UiO-66 (1%) membrane showed higher pure water flux than neat PSf membrane. Typical tradeoff between permeability and selectivity was witnessed within single filler MMMs (PSf/Zeolite4A and PSf/UiO-66). PSf/Zeolite4A@UiO-66 membranes didn’t show this tradeoff. All MMMs exhibited low nanofiller loadings (0.5 wt% and 1 wt%) showed improved FRR. Overall, PSf/Zeolite 4A@UiO-66 membranes presented better FRR among all MMMs.