Preparation and physicochemical characterization of highly efficient ZrO2/g-C3N4 composite catalysts for visible-light-driven removal of tetracycline antibiotics

Abstract

The increasing usage of antibiotics ultimately gave rise to potentially harmful effects for both the aquatic ecosystem and human well-being. The use of visible-light-driven photocatalysts is regarded as a very efficient approach for eliminating antibiotics present in wastewater. The primary objective of this work was the fabrication of zirconium dioxide modified with graphitic carbon nitride (ZrO₂/g-C₃N₄) composites to remove tetracycline (TC) antibiotics. The composites were analyzed using various characterization techniques, including XRD, FTIR, XPS, SEM, DLS, and BET analysis. The ZrO₂/g-C₃N₄ achieved a high removal efficiency of 93.18 % for TC in only 56 min under optimal reaction conditions (pH = 6, catalyst dose = 0.32 g/L, and TC concentration = 30 ppm), much higher than that of pristine ZrO₂ (67.73 %) and g-C₃N₄ (29.57 %). The enhanced catalytic efficacy of ZrO₂/g-C₃N₄ composites may be attributable to the great surficial area of ZrO₂/g-C₃N₄ (121.64 m²/g), in contrast to ZrO₂ (97.44 m²/g). The effects of pH, catalyst dose, and initiating concentration on the degrading efficiency of TC were thoroughly investigated. Radical quenching experiments and ESR analysis demonstrated that the major radicals responsible for the breakdown of TC were the hydroxyl (^•OH) and superoxide (O₂^•−) radicals, accompanied by the minor roles of electrons (e⁻) and holes (h⁺). This study presents a straightforward and economical approach for producing ZrO₂/g-C₃N₄ catalysts, which have excessive potential for practical applications in wastewater treatment and reclamation of the environment.