Microplastic removal from water using modified maifanite with rotating magnetic field affected

Abstract

Magnetic separation of microplastics from water is a new generation technology that is cost effective and environmentally friendly, and can avoid secondary pollution. The influence of magnetic Maifanite on polystyrene removal from water was investigated under a magnetic field action time, solution pH, magnetic carrier dosage, and polystyrene concentration, using a developed rotating magnetic field generator. Additionally, the polystyrene removal mechanism by the rotating magnetic field was revealed based on characterization and process simulation. The results showed that Maifanite can increase the number of surface adsorption sites and improve the adsorption performance after high temperature and acid impregnated modification. Specifically, the surface morphology of the modified Maifanite exhibited skirted stripes and a multilayered pore structure. And the specific surface area increased from 3.26 to 20.83 m2/g. The removal process is based on chemical adsorption, supplemented by physical adsorption. The magnetic carrier is tightly wrapped around the polystyrene surface by π bonds between the metal and hydroxy groups, ensuring agglomeration strength. Additionally, the rotating magnetic field generator designed can provide a rotating dynamic magnetic field, and the magnetic particles in the mixed system present a multi-directional helical motion trajectory, thus the walking displacement increases and the capture time decreases. And the probability of collision with non-magnetic particles and the formation of magnetic agglomerates are greatly increased. Thus the adsorption and removal of microplastics are enhanced theoretically. The polystyrene removal efficiency from water using modified Maifanite by rotating magnetic field affected increased by 19.49 %, reaching 98.46 %, and stabilizing at 86.53 % over 25 operation cycles. This study holds promise for advancing magnetic separation technology for microplastics from water.