Influence of Metal Ions (me: Fe, Cu, Co, Ni, Mn, Cr) on Direct Z-scheme Photocatalysts CN/Me-BTC on the Degradation Efficiency of Tetracycline in Water Environment

Background: The World Health Organization (WHO) reports that antibiotic resistance contributes to approximately 700,000 deaths yearly, with estimate suggesting a rise to 10 million deaths over the next 35 years. Methods: In this study, direct Z-scheme heterojunction photocatalysts CN/Me-BTC (CN: graphite carbon nitride, Me: metal ions, BTC: benzene-1,3,5-tricarboxylic acid) were successfully synthesized using a hydrothermal combined microwave method, eliminating the need for toxic solvents and featuring a short crystallization time and low reaction temperature. Significant findings: The study also explores the influence of various metal ions (Fe, Ni, Co, Mn, Cr, and Cu) on the morphological, physicochemical properties, and photocatalytic efficiency of tetracycline (TC) degradation. The CN/Me-BTC photocatalysts exhibit remarkable characteristics, including high visible light absorption, high surface area, low recombination rate between electrons and holes, and fast charge transfer ability. Among the synthesized photocatalysts, CN/FeBTC stands out with the highest efficiency in TC degradation (97.18 %) and degradation rate (decay constant k = 0.0197 min-1), surpassing CN by four times. The study comprehensively investigates factors influencing the TC degradation process, including catalyst mass, pH, antibiotic concentration, participating radicals, anions, and water sources. The mechanism of the photocatalytic process is elucidated based on radical quenching experiments and electrochemical properties.