Improving ofloxacin removal and antifouling performances of polysulfone-based mixed matrix membranes using chitosan-grafted UiO-66-NH2 MOFs

Polymeric membranes are widely used these days for wastewater treatment applications; however, in pressure-driven filtration processes, their intrinsic hydrophobicity often leads to severe fouling and reduced separation efficiency. In this study, a novel chitosan (CTS)-grafted metal-organic framework (UiO-66-CTS MOF) was synthesized and used as a stable filler in a polysulfone (PSF) matrix to enhance the hydrophilicity of resulting mixed matrix membranes (MMMs) and prevent nanoparticle agglomeration. CTS was grafted onto UiO-66-NH2 via a Schiff-base reaction, utilizing glutaraldehyde (GA) as a linker due to the presence of amino groups in both components. The successful synthesis of MOFs was confirmed by various characterization techniques, with the results demonstrating their effective formation. Separation performances of the prepared membranes were evaluated by pure water flux, pollutant rejection, and antifouling properties. Results revealed that UC-1.25 (containing 1.25% UiO-66-CTS) exhibited the best performance in the evaluation compared with pure PSF and U-1 (containing 1% UiO-66-NH2) membranes. UC-1.25 showed a significantly enhanced pure water flux of 2.92 L/m2.h, compared to 0.39 L/m2.h for the pristine PSF and 2.27 L/m2.h for U-1. In terms of pollutant rejection, UC-1.25 achieved 94.95% rejection of ofloxacin (OFL) antibiotics, outperforming PSF (71.33%) and U-1 (91.99%). Furthermore, UC-1.25 demonstrated improved antifouling behavior, with a flux recovery ratio (FRR) of 95.14%, whereas PSF and U-1 exhibited FRRs of 61.72% and 91.74%, respectively. These findings confirm that grafting CTS onto the UiO-66-NH2 MOFs effectively enhances the membrane’s hydrophilicity and separation performance.