Post-treatment of soft drink industrial wastewater using a new antibacterial ultra-filtration membrane prepared of Polyethersulfone blended with boehmite-tannic acid-graphene quantum dot.

Polymeric membranes have garnered great interest in wastewater treatment; however, fouling is known as their main limitation. Therefore, the blending of hydrophilic nanoparticles in polymeric membranes' structure is a promising approach for fouling reduction. Herein, a hydrophilic boehmite-tannic acid-graphene quantum dot (BM-TA-GQD) nanoparticle was synthesized and blended in a polyethersulfone polymeric membrane in different percentages. The fabricated membranes were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) images, water contact angle, porosity measurement, and antibacterial and antifouling properties. Surface SEM images of the modified membranes showed good dispersion of nanoparticles up to 0.5 wt%, which resulted in hydrophilicity and pure water flux enhancement. Based on AFM images, the mean roughness (Sa) of the fabricated membranes decreased from 2.07 to 0.84 nm for the bare and optimum membranes, respectively. In terms of performance, increasing the nanoparticle percentages up to 0.5 wt% resulted in the flux recovery ratio developing from 44.58% for the bare membrane to 71.35% for the 0.5 wt% BM-TA-GQD/PES membrane (optimum membrane). The antibacterial property of fabricated membranes was studied against biologically treated soft drink industrial wastewater (BTSDIW) as a bacterial source. The results showed that the turbidity of solutions containing permeated wastewater from the modified membranes (0.1, 0.5, and 1 wt% of BM-TA-GQD) was lower than that obtained from the unmodified membrane. These results confirmed the antibacterial properties of fabricated membranes. Finally, the optimal membrane (0.5 wt% BM-TA-GQD) was examined for post-treatment of the BTSDIW. An effluent COD of 13 mg/L and turbidity of 2 NTU showed a successful performance of the filtration process. PRACTITIONER POINTS: Ultrafiltration PES membranes were modified by different loadings of BM-TA-GQD. Hydrophilicity improvement was achieved by adding BM-TA-GQD nanoparticles. Expansion of size and number of macro-voids in modified membranes was confirmed. Membrane roughness was reduced in the BM-TA-GQD blended membranes. The optimum membrane was efficient in COD and turbidity removal.