Depollution of Effluents in Industrial Wastewater by Integrated Membrane and the Photocatalytic Processes: New Green Synthesis of Nanosized ZnO

New green synthesized ZnO nanostructures and ZnO-cellulose acetate (ZCA) integrated membrane exhibited a remarkable photodegradation efficiency for malachite green (MG) and methylene blue (MB) and Congo red dyes. Nano-sized ZnO powder was green synthesized through using Lycium barbarum L. leaf extract. The X-ray diffraction (XRD) analysis verified the formation of pure hexagonal ZnO structure. The transmission electron microscope (TEM) and scanning electron microscope (SEM) images displayed the well distribution ZnO particles with hexagonal and semi-spherical shapes. The green synthesized ZnO nanoparticles revealed a band gap energy of 3.02 eV. The Fourier transform infrared (FTIR) spectrum of ZnO powder demonstrated the characteristic absorption peaks of ZnO and –OH group of adsorbed water. Under natural sunlight, the green synthesized ZnO nanoparticles exhibits high photodegradation characteristics for malachite green (10–30 mg/L), methylene blue (20 mg/L) and Congo red (20 mg/L) in 100 min. The photodegradation efficiency of the ZnO catalyst was reached to 97, 95 and 98% for MG, MB and CR dyes, respectively. For practical photocatalytic process and catalyst recovering issue, ZnO nanoparticles-cellulose acetate (ZCA) integrated membrane was fabricated and examined for the photodegradation of the three dyes. The ZCA integrated membrane exhibits a remarkable photocatalytic degradation with efficacy of 80, 78 and 82% for MG, MB and CR dyes in 100 min of natural sunlight irradiation. The reusability of the green synthesized ZnO and ZCA integrated membrane continued with high photo-removal efficiencies for three cycles. The total organic carbon (TOC) analysis confirmed the high mineralization efficiency of ZnO and ZCA integrated membrane for MG, MB and CR dyes.