Nanofiltration of dye solution using chitosan/poly(vinyl alcohol)/ZIF-8 thin film composite adsorptive membranes with PVDF membrane beneath as support.

Nanobiocomposite adsorptive membranes were engineered by integrating metal-organic frameworks (ZIF-8), into the chitosan/poly(vinyl alcohol) blend and coating the blend on PVDF membrane support for an enhanced separation performance. The membranes were characterized by SEM, AFM, BET, XRD, ATR-FTIR and tensile stress analyses. The central composite design was utilized to optimize the water flux and dye rejection. Using CCD, the effect of the membrane thickness, PEG (pore-former), and chitosan content on the flux and rejection were studied. The optimal conditions were obtained as; 10 wt% PEG, 3 wt% chitosan, and 200 μm membrane thickness. The optimized flux and rejection were obtained 78.94 L m-2 h-1 and 90.3 %, respectively. The antifouling of the membranes was also examined by the filtration of BSA protein solution. The membranes showed comparable performance; however, extremely higher permeability (78.94 L m-2 h-1 bar -1) compared to similar TFC membranes that guarantee the economic favorability of the filtration process.