Wastewater treatment using a hybrid system combining adsorption, photocatalytic degradation and membrane filtration processes

Abstract

In the present study, Chooka’s Wastewater treatment was investigated using different combinations of adsorption, photocatalytic degradation, and membrane filtration process. Polymeric membranes were fabricated using wet phase inversion method employing polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and dimethylformamide (DMF) as a polymer matrix, hydrophilic additive, and solvent, respectively. Activated carbon and TiO2 nanoparticles were selected as an adsorbent and photocatalyst, respectively. TiO2 nanoparticles were synthesized using the sol-gel method and activated carbon was purchased from Merck Company. Liquid-liquid displacement (LLDP), scanning electron microscope (SEM) and contact angle tests were implemented to characterize the fabricated membranes. FT-IR and XRD analysis were also used for TiO2 nanoparticles characterization. The wastewater of Iran pulp and paper factory (Chooka) was used as the feed in separation processes. In hybrid separation systems, 6 different configurations were considered and wastewater compositions were measured to determine the effectiveness of the utilized processes before and after treatment. Accordingly, the mean pore size of the fabricated PAN/PVP (16%/3%) membrane obtained from LLDP analysis was 9.72 nm. SEM results also indicated thicker active layer for the PAN/PVP membrane than that of the neat PAN membrane. According to the results of the contact angle tests, with the increasing of PVP content in the polymer matrix, the hydrophilicity of membranes improved. It was also found that membrane filtration had the best performance among single stage processes and the best separation performance was achieved when photocatalytic degradation, adsorption, and membrane filtration were used in series, respectively.