Photocatalytic degradation of tetracycline and metronidazole in wastewater using Cu-chalcogenides/g-C3N4 composites

Abstract

The contamination of water resources by pharmaceutical compounds such as tetracycline (TC) and metronidazole (MZ) poses a significant environmental challenge. This study reports the synthesis, characterization, and application of g-C₃N₄-modified copper dichalcogenoimidodiphosphinate complexes as novel photocatalysts for the degradation of these pollutants under solar irradiation. Three composite materials (M408, M410, M409) were synthesized via solventless pyrolysis of g-C 3 N 4 with three Cu-chalcogenide complexes (Cu[(SePⁱPr 2 ) 2 N] 2 (C408), Cu[(SPⁱPr 2 )(SePⁱPr 2 )N] 2 (C410), and Cu[(SPⁱPr₂) 2 N] 2 (C409)). Among them, the M409 composite (Cu[(SPⁱPr 2 ) 2 N] 2 /g-C 3 N 4 ) demonstrated superior photocatalytic activity, achieving 88% and 85% degradation of TC and MZ (1 mg/L), respectively, within 180 min. Kinetic studies revealed that the degradation followed a pseudo-first-order Langmuir-Hinshelwood model, with the highest rate constants (k) observed at an initial concentration of 1 mg/L and a photocatalyst dose of 200 mg/L. The enhanced performance is attributed to the effective suppression of charge carrier recombination, as evidenced by photoluminescence spectroscopy. This work establishes these modified metal chalcogenide complexes as effective solar-active photocatalysts for wastewater remediation.