Improving selectivity and antifouling properties of a PES hollow fibre membrane with a photo-enzyme for the removal of ciprofloxacin and sulfamethoxazole

A multifunctional hollow fibre was prepared by the modification of polyethersulfone (PES) with laccase (Lac) and phosphorus-doped graphitic carbon nitride (P-gC₃N₄) for the removal of ciprofloxacin and sulfamethoxazole. The properties and structure elucidation of the prepared membranes were evaluated using contact angle analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), correlative light electron microscopy (CLEM), atomic force microscopy (AFM), tensile strength, water-intake capacity, and pure water flux. The modified multifunctional hollow fibre membranes showed increased root mean square surface roughness from 50 nm for neat PES to 104 nm, which contributed to the significantly higher water flux of 90 L.m⁻²h⁻¹ compared to 54 L.m⁻²h⁻¹ for pristine PES. The hydrophilicity also improved after modification as the contact angle reduced from 72° ± 1.01° to 42° ± 2.26°. The modified hollow fibre membranes showed an enhanced removal of ciprofloxacin (77%) and sulfamethoxazole (80%). Moreover, antifouling properties towards bovine serum albumin were 89% for FRR, 7% for R_r, 9% for R_ir and 17% for R_t. Regeneration studies showed that the multifunctional hollow fibre membrane obtained a high removal percentage of 79% towards sulfamethoxazole after five cycles. Hence, this work proposes a new system that can be successfully utilized in the treatment of emerging pharmaceutical pollutants in water.