Preparation of Fe3O4/polysulfone ultrafiltration membrane and its adsorption of phosphate from aqueous solution

ABSTRACT The fabrication of mixed matrix membranes (MMMs) is a promising method to improve the properties of polymer membrane. In this study, composite polysulfone (PSf) membrane was prepared by blending Fe 3 O 4 nanoparticles (NPs) via non-solvent induced phase separation (NIPS) method. The as-prepared Fe 3 O 4 /PSf membranes with different Fe 3 O 4 loadings (60% and 120%) were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The membrane porosity, pore size, water flux, water contact angle, and bovine serum albumin (BSA) rejection were also analyzed. The presence of Fe 3 O 4 NPs accelerated the phase inversion kinetics;therefore, membranes with opener finger-like structure and higher porosity were obtained. The Fe 3 O 4 /PSf membranes also demonstrated remarkable fouling resistance. When a 0.3 g·L –1 BSA solution was used as feed, the stable flux after 2 h filtration markedly increased by over 20 times compared to the pristine PSf membrane. Batch adsorption tests indicated that the composite membranes can effectively remove phosphate at pH ranging from 4 to 8. The adsorption kinetics can be fitted by both pseudo-first order and pseudo-second order models with correlation coefficients higher than 0.96. Intra-particle diffusion was not the rate-limiting step in the whole adsorption process. The maximum adsorption capacity obtained by Langmuir isotherm was 0.684 mg-P·g –1 for 120% Fe 3 O 4 /PSf membrane. In addition, the phosphate adsorption capability of the proposed Fe 3 O 4 /PSf membrane can be well recovered after regeneration using a 0.01 mol·L –1 NaOH solution.