Solar-driven photocatalytic degradation of reactive red 24 using tragacanth gum-stabilized FeS2/g-C3N4 heterostructures for sustainable water remediation.

Abstract

Biopolymeric heterostructure semiconductors are continuously being improved for efficient charge separation. Herein, a Tragacanth gum-mediated FeS₂/g-C₃N₄ heterostructure (TFCN) was successfully prepared for solar-driven degradation of organic dyes. The composite was characterized using XRD, FTIR, SEM, UV-Vis Spectroscopy, Zeta Potential and Brunauer-Emmett-Teller (BET) surface analysis. TFCN produced well-defined and evenly distributed grains measuring 0.56 µm. The zeta potential of -54.10 mV disclosed that the TFCN photocatalyst possessed strong electrostatic repulsion and good colloidal stability. TFCN showed superior sunlight-driven photocatalytic degradation of RR 24 (93.57%) compared to FeS₂ (FS), g-C₃N₄ (CN)_, following pseudo first order kinetics, exhibiting rate constant of 0.03122 min^-1 and R² value of 0.99087. The high degradation efficiency of TFCN is due to synergism between TG, FS, and CN, which enhances the separation of the photogenerated electron/hole pairs. The proposed photocatalytic mechanism confirmed the prominent role of superoxide (O₂^•-) radicals in the degradation of RR 24 dye. The negative ΔG° (-7.41 J mol^-1 K) and the positive ΔH° (41.47 J mol^-1) of TFCN indicated its thermodynamically feasible endothermic nature, making it an attractive candidate for water purification.