Graphitic carbon nitride nanotubes decorated with ruthenium: New efficient visible-light-driven photocatalyst

Abstract

The discharge of effluents containing antibiotics into the environment poses a significant challenge, contributing to the proliferation of resistant bacterial pathogens. Consequently, the removal and degradation of these contaminants from aqueous environments, particularly through photodegradation with potent photocatalysts, has attracted considerable research interest. In this research, A novel generation of visible-light photocatalyst was developed by immobilizing a ruthenium complex on modified graphitic carbon nitride nanotubes, with a focus on degrading the commonly used antibiotic, tetracycline. To achieve this, the synthesis of graphitic carbon nitride nanotubes (g-C₃N₄ NTs) was successfully conducted using the hydrothermal method, followed by functionalization with the 1,10-Phenantroline-5,6-dione ligand. Subsequently, the functionalized g-C₃N₄ NTs were further enhanced through the immobilization of dichloro(p-cymene)ruthenium(II) dimer. The structure and morphology of the prepared photocatalyst were analyzed using X-ray diffraction (XRD), Fourier transform infrared (FT-IR)spectroscopy, and scanning and transmission electron microscopy (SEM & TEM). Subsequently, the photocatalyst’s efficiency in optically degrading tetracycline antibiotics was evaluated in a suspension reactor equipped with a 60 W LED lamp. Key parameters such as catalyst dosage, irradiation duration, temperature, and pH were systematically optimized. The results indicated that the immobilization of the Ru complex onto functionalized g-C₃N₄ NTs significantly enhanced photocatalytic activity, resulting in a 43 % increase in degradation efficiency. Furthermore, Chemical Oxygen Demand (COD) analysis demonstrated that approximately 90 % mineralization of a 10 mg/L tetracycline solution could be achieved using 20 mg of Ru (II) complex/g-C₃N₄ NTs at pH 7 after 480 min, without the need for additional oxidants.