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

Nanofiltration membrane with good separation performance can effectively remove dyes from wastewater. A new type of composite membrane (TiO 2 /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 (TiO 2 )/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 TiO 2 content on permeability and retention of membrane was discussed. Results demonstrate that TiO 2 /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 Na 2 SO 4 , NaCl, MgSO 4 and MgCl 2 , 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.