Photocatalytic degradation of tetracycline using visible-lightdriven porous g-C3N4 nanosheets catalyst

Abstract

Tetracycline is one of the most widely prevalent antibiotics, and it is used for both veterinary and human medical care purposes. Tetracycline is not fully absorbed in the digestive tract of humans and animals, and it is estimated that approximately 50% is excreted through urine and faeces and enters the environment as the parent compound of one of its metabolites. Conventional wastewater treatment processes have been shown to be inefficient in degrading tetracycline resulting in bioaccumulation of the compound. Advanced Oxidation Processes (AOPs) such as heterogeneous photocatalysis have been shown to be an efficient and eco-friendly technology for the removal of refractory organic pollutants from wastewater. This study investigates the use of graphitic carbon nitride as a photocatalyst for the degradation of tetracycline in wastewater. The catalyst was synthesized through pyrocondensation polymerization. X-ray diffraction analysis confirmed formation of the desired material. The efficacy of the synthesized material was investigated using a batch reactor set-up under ultraviolet and visible light irradiation. The control adsorption experiments showed 4.4 % tetracycline removal after 2 h, while visible light photolysis resulted in 21.9 % degradation in the same period. These results were markedly lower than the 76.7 % degradation observed under visible light activated photocatalysis conditions. Process parameter optimization experiments revealed that a catalyst loading of 1 gL-1 and pH of 7.00 resulted in 77 % tetracycline degradation after 2 h of visible light irradiation.