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

This study investigated the photodegradation of microplastics (MPs) by alpha-Fe2O3/g-C3N4. The effects of alpha-Fe2O3/g-C3N4 on MPs' surface were investigated through various techniques. With the addition of alpha-Fe2O3/g-C3N4 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 alpha-Fe2O3/g-C3N4 was added. Specifically, polystyrene films and particles in water showed 9.94% and 7.81% increased mass loss, respectively. The degradation of MPs using alpha-Fe2O3/g-C3N4 demonstrated the behavior consistent with the pseudo-first-order kinetic model. The presence of alpha-Fe2O3/g-C3N4 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 alpha-Fe2O3/g-C3N4 significantly increased, and the detection of carboxyl bands indicated the formation of carboxylic acid, ketones, and lactones as degradation products.