Hybrid polystyrene nanoparticle-ultrafiltration system for hormone removal from water

Occurrence of hormones in water resources even at low concentrations of ng/L is a potential risk for both environmental and public health. Hybrid sorbent-ultrafiltration (UF) systems are among the technologies under investigation for their potential as a sustainable and energy-efficient process for the removal of hormones from water. In this study polystyrene (PS) nanoparticles were explored as sorbent in a hybrid system. Estrone adsorption capacity of 52 nm PS nanoparticles was found to be 79.6 ng/g at equilibrium estrone concentration of 5.9 ng/L. The performance of the hybrid PS nanoparticle-UF system was studied in terms of adsorption and membrane permeability under varying solution pH, particle size and particle concentration. The results indicated that neutral pH range is optimal for operation of the system and estrone removal with nanoparticles above 465 nm is negligible. The highest estrone removal (40%) was achieved by the hybrid system using a 100 kDa UF membrane and 84 mg/L PS (52 nm) nanoparticle concentration. The capacity of the system to remove estrone was found to be lower than most nanofiltration/reverse osmosis (NF/RO) systems but with a final permeability of 75 L/m² h bar, at least five times higher than most of the NF/RO systems.