Polyethersulfone membranes modified with CZTS nanoparticles for protein and dye separation: Improvement of antifouling and self-cleaning performance

Abstract

In this study, a novel polyethersulphone (PES) nanocomposite membrane incorporated with copper zinc tin sulfide (Cu2ZnSnS4) nanoparticles (CZTS NPs) was prepared through the phase inversion method. First, the samples containing different copper and zinc ratios in CZTS stoichiometry were prepared and characterized. The effect of copper and zinc ratio changes were examined on the photocatalytic properties of both NPs and nanocomposite membranes. The photocatalytic effect was tested and BR18 dye was degraded at 88.0% efficiency when exposed to visible light for 180 min in the presence of CZTS1.0 NPs catalyst. The results also exhibited that CZTS NPs blended membrane showed good self-cleaning performance. Second, we investigated the antioxidant, DNA cleavage, and biofilm inhibition activities of CZTS NPs. The antimicrobial activities of CZTS NPs were tested against seven microbial strains. The highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging and chelating activities were found as 81.80 ± 1.75% and 72.19 ± 4.63%, respectively. CZTS NPs exhibited double-strand DNA cleavage activity at 500 mg/L. They showed significant biofilm inhibition as 92.15 ± 5.67% against Staphylococcus aureus. CZTS NPs displayed moderate antimicrobial effects against tested microorganisms. Third, CZTS NPs were blended in polyethersulphone (PES) membrane and the morphology as well as performance of the fabricated nanocomposite membranes were systematically investigated by SEM-EDX, porosity, water contact angle, antifouling, and rejection measurements. The water flux of resulting nanocomposite membranes was markedly enhanced due to the introducing of CZTS NPs. Meanwhile, the nanocomposite membranes demonstrated remarkable antifouling properties (flux recovery ratio ∼94%) in contrast with the bare PES (flux recovery ratio ∼51%) when BSA was filtrated. The high retention of BSA (100%) as well as high permeation flux (73.8 ± 9.8 L/m2/h) of the CZTS2.00 wt% membrane demonstrated that the constructed nanocomposite membrane possessed the characteristics of a promising membrane for purification of proteins.