High-performance f-GO/MWCNTs-COOH nanohybrid-based polylactic acid mixed matrix membrane for wastewater treatment

To enhance the green polylactic acid (PLA) membrane's efficiency for removing organic materials, self-assembled functionalized graphene oxide carboxylic multi-walled carbon nanotubes (f-GO/MWCNTs-COOH) was incorporated into the membrane matrix followed by immersion precipitation. The successful formation of the negatively charged f-GO/MWCNTs-COOH nanohybrid was verified by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and zeta potential analyzer. The effect of different nanohybrid contents (1.5, 3 and 6 wt%) on the PLA membrane performance was investigated. The prepared mixed matrix membranes were analyzed by FT-IR, XRD, SEM, contact angle, porosity, and pore size analysis. Synthetic organic foulant bovine serum albumin (BSA), humic acid (HA) solutions were utilised to test the antifouling behaviour of membranes. In addition, raw wastewater from a wastewater treatment plant (WWTP) was used to further assess the performance of the membranes. The results indicated that with only 3 wt% f-GO/MWCNTs-COOH nanohybrid in the PLA membrane matrix, the fouling tendency was attenuated (superior rejection rates for BSA and HA of 96 % and 98 %, respectively.) and the pure water flux was increased to almost 80 L/m2hbar, compared to the neat PLA membrane (27 L/m2hbar), without compromising the high organic removal efficiency. According to the results of this study, the f-GO/MWCNTs-COOH nanohybrid has great potential to enhance the performance of mixed matrix membranes in raw wastewater treatment applications.