Fabrication, characterization, and application of PSf/Ni@ZnO amalgamated membrane for photocatalytic degradation of dyeing wastewater from batik industry

The ultraviolet-light-driven composite membrane incorporated with nickel@zinc oxide (Ni@ZnO) photocatalyst for batik wastewater treatment is demonstrated in this study. Co-precipitation and non-solvent-induced phase separation techniques were directed to fabricate the nanocomposite membranes. Based on characterization results, the scanning electron microscope and energy dispersive X-ray analyses showed a large surface pore of the polysulfone (PSf)/Ni@ZnO membrane with a well-arranged loose-spongy structure and a predominant presence of elemental O, compared to the pristine membrane. The improved photocatalytic activity was observed by a decreased ZnO band-gap energy from 3.31 to 3.07 eV after nickel doping. Based on the atomic force microscope results, the addition of Ni@ZnO promoted a rougher surface membrane, while also increasing the porosity, hydrophilicity, water uptake ability, and mechanical strength of PSf membrane. Furthermore, PSf/Ni@ZnO 1% (w/w) showed the best performance in photodegradation-filtration systems with 10 times higher permeability than pristine PSf; total dissolved solid, chemical oxygen demand, and dye removal were 26.4%, 33.5%, 92.2%, respectively; with photodegradation efficiency reaches 53.26%. The photodegradation stability test for five consecutive cycles also revealed that PSf/Ni@ZnO 1% (w/w) was 62.5% more reactive than PSf/ZnO, which was established by its fresh and recycled crystal structure membranes. Thus, the PSf/Ni@ZnO 1% (w/w) membrane was out to be the most outstanding ultraviolet-light-driven photocatalytic membrane for efficient batik wastewater treatment.