Cadmium Sulfide-Modified Carbon Nitride/Graphite for Photocatalytic Removal of Sulfamethoxazole From Aqueous Solutions

Background: Sulfamethoxazole (SMX), a sulfonamide antibiotic, is frequently detected at high concentrations in surface and drinking water, indicating widespread contamination. Methods: In this experimental study, a graphitic carbon nitride (g-C3 N4 )/cadmium sulfide (CdS) nano-composite was synthesized using a co-precipitation method. The crystal structure, morphology, and surface chemistry of the synthesized nanocomposite were characterized using X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX), respectively. The Experiments were conducted under varying conditions, including pH (3–11), nanocatalyst dosage (0.2–1 g/L), contact time (0–120 minutes), and initial SMX concentration (5–20 mg/L). Results: XRD and SEM analyses confirmed the hexagonal structure of CdS, with SEM images showing well-dispersed nanoparticles and no agglomeration. The distinct peaks in the XRD pattern indicated well-crystallized CdS nanoparticles. Optimal removal efficiency was achieved at pH 5, with a nanocatalyst dosage of 0.7 g/L, a contact time of 60 minutes, and an SMX concentration of 5 mg/L. Kinetic studies revealed that the photocatalytic degradation followed first-order kinetics (R2=0.9955). Conclusion: Based on the results and the physical and chemical properties of the synthesized CdS-modified carbon nitride nanocomposite, this photocatalytic process offers a promising, effective, and efficient method for the treatment of antibiotic-contaminated wastewater, particularly for removing SMX.