Rejection of antibiotics using modified polyvinylidene fluoride (PVDF) membranes with polyethyleneimine co-blending: Relating membrane performances to operating conditions

Modified polyvinylidene fluoride (PVDF) membranes were prepared using co-blending modification with polyethyleneimine (PEI). The rejection of target antibiotics, sulfamethoxazole (SMX) and tetracycline (TC) and the improvement of PEI on the various properties of PVDF based membrane were explored. The GH-1 membrane, formulated with 0.1 g PEI per 100 g casting solution, exhibited excellent performance with a stable water flux of 280 L/(m²·h) at 0.10 MPa and high rejection rates of 98.7% for SMX and 57.7% for TC in simulated water, and 90.7% for SMX and 83.1% for TC in river water. GH-1 featured nano-sized micropores, enhanced hydrophilicity, and was influenced by operating conditions such as trans-membrane pressure, pH, feed concentration, and ionic strength. Antibiotic removal was affected by charge interactions between the membrane and antibiotics at varying pH levels. While humic acid and cations promoted fouling, they enhanced antibiotic removal. GH-1's removal mechanism included spatial hindrance, porous adsorption, pH-induced Donnan exclusion, and fouling layer effects. The membrane showed good anti-fouling properties with 87.0-96.0% flux recovery after cleaning. • PEI co-blending modified PVDF membrane GH-1 had high flux and antibiotic rejection. • Rejection of sulfamethoxazole and tetracycline from water reached 98.7% and 57.7%. • GH-1 showed its good membrane anti-fouling performance. • Rejection resulted from spatial site hindrance, Dannon exclusion, fouling layer, etc. • GH-1 had high removal of antibiotics and conventional pollutants from river water.