Synthesis of Exfoliated Graphitic Carbon Nitride (g-C3N4) for Tetracycline Hydrochloride (TCH) Degradation: Photocatalytic Efficiency and Mechanisms

Abstract

The article highlights the effectiveness and simplicity of thermally exfoliated graphitic carbon nitride (g-C₃N₄) for the degradation of tetracycline hydrochloride (TCH) in the presence of solar light. The study investigates the thermal exfoliation of g-C₃N₄ derived from thiourea at five distinct temperatures (450, 475, 500, 525, and 550 °C). Various characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer–Emmett–Teller (BET) analysis, were employed to analyze the materials’ shape, composition, crystallinity, and inherent photoresponsive qualities. With a catalyst dosage of 0.4 g/L, approximately 71% of TCH (initial concentration of 10 mg/L) was degraded after 60 min of direct sunlight exposure. The findings revealed that TOC elimination was 69% with 10 mg/L of TCH for 60 min, which corresponds to the degradation results. The degradation followed pseudo-first-order kinetics, with a rate constant of 0.020 min⁻¹ (R² = 0.997). Superoxide radicals \(O_{2}^{ - \cdot }\) were identified as the primary reactive species responsible for TCH degradation through scavenging agent trapping tests. The catalyst demonstrated excellent stability over five reuse cycles, indicating its potential for environmental applications.