Photocatalytic degradation of polyethylene and polystyrene microplastics by α-Fe2O3/g-C3N4

Abstract This study investigated the photodegradation of microplastics (MPs) by α-Fe 2 O 3 / g -C 3 N 4 . The effects of α-Fe 2 O 3 / g -C 3 N 4 on MPs' surface were investigated through various techniques. With the addition of α-Fe 2 O 3 / g -C 3 N 4 and under visible light irradiation, cracks and folds were observed on the MP films and particles. Compared to the treatment without photocatalyst addition, the mass loss of MPs increased with irradiation time when α-Fe 2 O 3 / g -C 3 N 4 was added. Specifically, polystyrene films and particles in water showed 9.94% and 7.81% increased mass loss, respectively. The degradation of MPs using α-Fe 2 O 3 / g -C 3 N 4 demonstrated the behavior consistent with the pseudo-first-order kinetic model. The presence of α-Fe 2 O 3 / g -C 3 N 4 led to an increase in surface oxygen-containing functional groups and crystallinity while decreasing the average molecular weight of MPs. After 30 days of irradiation, the characteristic tensile bands of MPs with α-Fe 2 O 3 / g -C 3 N 4 significantly increased, and the detection of carboxyl bands indicated the formation of carboxylic acid, ketones, and lactones as degradation products.