Simultaneous photodegradation of antibiotics and non-steroidal anti-inflammatory drugs in different aquatic environments using Z-scheme Ag/Ag₃PO₄/g-C₃N₄ photocatalyst under simulated sunlight irradiation.

The widespread presence of pharmaceuticals and antibiotics in aquatic environments poses a serious ecological and public health risk, necessitating effective removal strategies. This study investigates a Z-scheme Ag/Ag₃PO₄/g-C₃N₄ photocatalyst for the simultaneous photodegradation of sulfamethoxazole, trimethoprim, naproxen, and diclofenac under visible light, a topic that has not been previously reported. The photocatalyst was comprehensively characterized using XRD, XPS, FTIR, BET, FESEM-EDX, TEM, EIS, PL, and DRS. Among the synthesized variants, Ag/Ag₃PO₄/g-C₃N₄ (80%) exhibited the highest photocatalytic efficiency. Optimal operational parameters (pH 6, 30 min irradiation, and 1.170 g L⁻¹ catalyst dosage) were established using response surface methodology based on a central composite design. Under these conditions, complete pollutant removal was achieved, with a total organic carbon (TOC) reduction of 88.62% after 180 min. Kinetic studies followed a pseudo-first-order model, and scavenger tests identified photogenerated holes (h⁺) as the dominant reactive species. Transformation products were identified using LC/MS. The photocatalyst retained high activity after five reuse cycles, confirming its stability and reusability. The superior performance is attributed to the Z-scheme mechanism and silver-induced surface plasmon resonance (SPR). The integration of advanced nanostructuring, heterojunction interface engineering, and statistical optimization enables efficient degradation of pharmaceutical mixtures at environmentally relevant concentrations in real water samples, highlighting its strong potential for sustainable water purification applications.