An adsorptive sulfonated polyethersulfone/functionalized graphene ultrafiltration membrane for hardness removal

A sulfonated polyethersulfone/functionalized graphene membrane (SPES/CSrGO) was developed through a facile ‘one-pot’ method for hardness removal. The concentrated sulfuric acid (H 2 SO 4 ) was used as both sulfonating agent for PES materials and solvent for preparing casting solution of SPES/CSrGO. The sulfonic acid group of SPES could form hydrogen bond with carboxyl group on CSrGO, improving the dispersibility of CSrGO in membrane. The SPES/CSrGO membrane with uniform dispersion of CSrGO showed good adsorption–desorption behavior in static adsorption. The SPES/CSrGO membrane with CSrGO content of 30 wt% (SPES/CSrGO-30) showed the highest static adsorption capacities for Ca 2+ (82.52 mg/g) and Mg 2+ (74.21 mg/g), respectively. In artificial seawater, the SPES/CSrGO-30 membrane also exhibited good adsorption performance and the adsorption capacities of Ca 2+ and Mg 2+ reached 26.27 mg/g and 50.1 mg/g. In dynamic adsorption, the adsorption capacities of SPES/CSrGO-30 for Ca 2+ and Mg 2+ were 43.63 mg/g and 34.29 mg/g, respectively. More importantly, the hydrophilicity CSrGO endowed the excellent antifouling property of SPES/CSrGO membrane. This strategy showed a high potential for the removal of hardness during the ultrafiltration process and provided a promising direction to the design of high-performance adsorptive membranes.