Styrene-maleic anhydride/polyethersulfone blending membranes modified by PEI functionalized TiO2 to enhance separation and antifouling properties: Dye purification

Abstract Nanofiltration membrane with good separation performance can effectively remove dyes from wastewater. A new type of composite membrane (TiO2/PEI/PDA-SMA/PES), which possesses excellent dye/salt separation property, was facilely manufactured by a combined strategy of mixing styrene-maleic anhydride (SMA) with polyethersulfone (PES), polydopamine (PDA) coating, titanium dioxide (TiO2)/polyethylenimine (PEI) co-deposition and cross-linking. The as-prepared membranes were characterized using SEM, AFM, FTIR, surface zeta potential, water permeability and contact angle measurement. The effect of TiO2 content on permeability and retention of membrane was discussed. Results demonstrate that TiO2/PEI/PDA-SMA/PES membrane is hydrophilic and positively charged, and it exhibits high permeability for pure water (73.2 L·m−2·h−1·bar−1), reasonable retention to dyes (98.6%, 92.3% and 90.4% for Congo Red, Rhodamine B and Crystal violet, respectively) and satisfactory transport to salts (39.5, 36.4, 30.6 and 29.4 L·m−2·h−1·bar−1 for Na2SO4, NaCl, MgSO4 and MgCl2, respectively). In addition, the membrane shows a great antifouling performance and long-term stability during the filtration of dye/salt simulated wastewaters. Further, the membrane is used to treat actual textile wastewater. It also shows good separation performance (permeability 10.6 L·m−2·h−1·bar−1, COD retention 98.2%, and color retention 99.7%). Perhaps it is fit for potential treatment of textile wastewater.