Removal of organic pollutants from rubber wastewater using hydrophilic nanocomposite rGO-ZnO/PES hybrid membranes

The introduction of membrane filtration for rubber wastewater treatment, the utilization of treated wastewater as recycled process water to minimize water demand during processing becomes possible. In this work, novel polyethersulfone (PES) nanohybrid membranes incorporating low loadings of ZnO nanoparticles (NPs), reduced graphene oxide (rGO), and their combination were investigated. Characteristics alteration of the membrane were confirmed using a scanning electron microscope (SEM), Fourier transform infra-red (FTIR), x-ray diffraction (XRD), contact angle, and porosity structure. The SEM images showed a reduction of NPs agglomeration by the addition of rGO. The dual filler rGO/ZnO has exhibited significant improvement in the membrane structure, wettability, and mechanical strength. The modified membranes also exhibited better separation performances as compared to the neat PES membrane. The average permeate flux was enhanced from 2.69 to 11.51 L m⁻²h. a remarkable pollutant reduction was shown by the chemical oxygen demand (COD), NH₃, and turbidity rejection up to 92%, 88%, and 99%, respectively for PES-rGO/ZnO membrane. The flux recovery ratio of the modified membrane was recorded to be 82%, 80.21%, and 83% for PES-ZnO, PES-rGO, and PES-rGO/ZnO, respectively which was 7–12% higher than neat PES membrane. The cleaning under UV light can increase the flux recovery ratio (FRR) up to 14% due to the photocatalytic activity of ZnO and rGO that helped to degrade the organic fouling. The results obtained in this study are expected to have great potential on membrane studies, particularly for high-organic content wastewater treatment.