Photocatalytic polysulfone membrane incorporated by ZnO-MnO2@SiO2 composite under UV light irradiation for the reliable treatment of natural rubber-laden wastewater

Abstract

The effects of adding zinc oxide-manganese oxide @ silicon dioxide (ZnO-MnO2@SiO2) photocatalyst composite to polysulfone (PSf) membrane that was performed for natural rubber-laden wastewater (NRW) treatment are presented in this study. The sol–gel method was adopted to synthesize the photocatalyst composites, and the non-solvent induced phase separation (NIPS) technique was applied to synthesize the membranes. The PSf/ZnO-MnO2@SiO2 membrane has a smooth surface with a well-constructed finger-like structure and a fairly uniform dispersion of photocatalyst elementals on its surface, according to SEM and EDX mapping data. From AFM results, the addition of ZnO-MnO2@SiO2 photocatalyst resulted in a rougher surface image. In the FTIR spectrum of PSf/ZnO-MnO2@SiO2 membrane, many new polar functional groups such as Zn-O, Mn-O, and Si-O-Si were identified. The MnO2 doping in the composite successfully increased the photo-sensitivity and photocatalytic activity of the composite, implying that the bandgap energy was reduced from 3.10 eV to 2.65 eV, promoting photocatalytic improvement. The membrane porosity, hydrophilicity, water absorption ability, and mechanical strength are all enhanced with the addition of the ZnO-MnO2@SiO2 photocatalyst. Performing the PSf/ZnO-MnO2@SiO2 membrane under UV light irradiation significantly improved the flux stability, membrane recyclability, and antifouling properties that prevented the fouling formation and prolonged the usability of the membrane. In conclusion, the PSf/ZnO-MnO2@SiO2 membrane is determined to be the most promising UV light-driven photocatalytic membrane for successful NRW treatment based on all attributes and performance.