Preparation and characteristics of antibacterial PVDF ultrafiltration membrane modified with co-blending of ciprofloxacin and sulfamethoxazole

Abstract

Ciprofloxacin (CIP) and sulfamethoxazole (SMX) were used for the co-blending modification of polyvinylidene fluoride (PVDF) ultrafiltration membranes. The modified membranes were prepared by adding 0.4 g, 0.6 g, 0.8 g, and 1.0 g of CIP and SMX (mass ratio at 1:1) to each 100 g of casting solution, marked as SC0.4, SC0.6, SC0.8, SC1.0, respectively. The -COOH and -NH2 groups on the CIP and SMX molecules would narrow the mixing gap between the solvent and non-solvent, promote phase separation in PVDF membrane formation, and increase thermodynamic instability, leading to more pores in the modified membrane. The modified membranes, with the addition of CIP and SMX, resisted the attachment of bacteria while inactivating them. They all showed good inhibition of non-specific bacteria in urban rivers, with SC0.6 (about 5 cm in diameter) producing a bacteriostatic circle width of 0.50–0.92 mm. Also, they showed excellent algal removal effects. The antibiotics had good stability inside the modified membranes which could keep a stable antibacterial performance. The filtration performances were found to be best in SC0.6. Compared with the base membrane, the flux recovery rate of SC0.6 was improved by 16.6 % and the adsorption of BSA was reduced by 69.7 % due to the increased hydrophilicity and porosity as well as reduced pore size of the modified membrane. In addition, the removal of conventional pollutants in urban rivers for the modified membranes was also improved. Therefore, the co-blending modification with CIP and SMX could effectively improve the anti-biofouling and filtration performances of the membranes.