Synergistic removal of naproxen through photocatalytic activation of peroxymonosulfate using g-C3N4

Sulfate radical-based advanced oxidation processes have gained significant attention in recent years. In this research, potassium peroxymonosulfate (PMS) was employed to oxidize naproxen (NPX) in an aqueous solution. Promoted PMS activation for NPX degradation was studied in the presence of g-C3N4, both in the dark and under UVA-365 nm irradiation. The PMS/g-C3N4/UVA system remarkably promotes NPX degradation, reaching 99.6 % in only 15 mins, with a mineralization rate of 91 % within 8 h. The apparent rate constant 'k' of NPX degradation by PMS/g-C3N4/UVA system (0.49 +/- 0.01 min-1) was approximately 3.7 times higher than the sum of g-C3N4/UVA (0.116 +/- 0.003 min-1) and PMS/g-C3N4 (0.015 +/- 0.002 min-1). The promoted photo- catalytic performance is attributed to the synergistic effect between g-C3N4 and PMS. In this system, g-C3N4 serves as both an efficient photocatalyst and a promoter for PMS activation, while PMS acts as an electron acceptor, significantly boosting the efficiency of the system. The primary active species involved in NPX degradation in different systems were studied by adding various scavengers. The results indicate that photo- excited holes (h+) and superoxide radicals (O2 & sdot;-) are the main contributors. However, the role of SO4 & sdot;- and & sdot;OH becomes more significant as the concentration of PMS increases.