The removal characteristics and mechanisms of polystyrene microplastics with various induced photoaging degrees by CuFe2O4

Environmental microplastics play an important role in the transmission of pollutants due to their complex properties. To remove microplastics from water, a magnetic material CuFe2O4 was used to remove microplastics with different photoaging degrees, which has the advantage of being fast and efficient. CuFe2O4 had an excellent characteristic in the removal of polystyrene microplastics and its superparamagnetic nature ensured its magnetic recovery. When the dosage of CuFe2O4 was 0.2 g L-1, the removal efficiencies of 98.02, 94.07 and 96.93% could be achieved for the pristine, aged 36 h and aged 84 h polystyrene microplastics (PSMP) with initial concentration of 0.04 g L-1, respectively. In addition, the high removal efficiency was also achieved in actual water. The impacts of different environmental factors on the removal efficiency were in the order of dissolved organic pollutants > pH > salt ion concentration. Hydrogen bonding played a key role in the removal of pristine polystyrene microplastics and the destruction of C = O by Fe-OOH also played an important role in the removal of aged polystyrene microplastics. Pyrolysis at 500 degrees C of 4 h can regenerate it, and the removal efficiency for PSMP can still reach 83.88% after four times of reuse.