Diatomite-Supported SnO ₂ /g-C ₃ N ₄ Nanocomposites for Efficient Degradation of Organic Pollutants Under Visible Light

Worsening water contamination by organic pollutants, such as industrial dyes, mineral processing reagents, and medical antibiotics, calls for the design of efficient and inexpensive remediation technologies. Herein, a new ternary nanocomposite photocatalyst SnO 2 /g-C 3 N 4 /Dt was prepared by a simple hydrothermal method and calcination, exploiting the strong photocatalytic activity of SnO 2 and g-C 3 N 4 , and the structural dispersion ability of diatomite (Dt) to construct a stable heterojunction system. Characterization results indicated that a large specific surface area, optimized pore structure, and abundant active sites were obtained, while agglomeration of nanoparticles was effectively suppressed. Under simulated visible-light irradiation, the ternary composite exhibited a broad photocatalytic activity with degradation percentages of Methyl Orange (MO), Sodium Ethyl Xanthate (SEX), and Tetracycline Hydrochloride (TCH) of 94.29%, 99.63%, and 93.31% in 60 minutes - significantly better than its single and binary counterparts. The degradation process followed pseudo-first-order kinetic behavior, with degradation rates improved by 3.5-4.1 times compared to the pristine materials. Recycling experiments also demonstrated that the SnO 2 /g-C 3 N 4 /Dt nanocomposite exhibit excellent reusability as photocatalysts and hold significant potential for application in the treatment of industrial wastewater containing organic pollutants.