Synergistic effects of the pyrite and graphitic carbon nitride-based bio-polymer composite for enhancing the photocatalytic degradation of reactive red-24 dye

Abstract

The design of photocatalysts with optimized properties to effectively degrade persistent and resilient pollutants, such as dyes, is a topic of great interest. Herein, we describe the use of a simple ultrasonic method to prepare a gelatin-based FeS₂-gC₃N₄ (GL/FS-CN) composite for the photocatalytic degradation of the reactive red 24 (RR 24) dye. The GL/FS-CN composite was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) spectroscopy, scanning electron microscopy (SEM), N₂ adsorption at −196 °C, zeta potential analysis, and X-ray photoelectron spectroscopy. The photocatalytic degradation of 91.78% achieved with GL/FS-CN demonstrates a notable improvement over FS and CN, highlighting the potential of this method for enhancing photocatalytic efficiency. The presence of gelatin with FS and CN helped enhance photocatalytic efficiency and reduce the recombination rate. The main active species involved in degradation were superoxide radicals (O₂˙⁻), as the degradation efficiency decreased to 78.22%, 80.13%, and 55% when EDTA, IPA, and BQ were added as sacrificial agents, respectively. The photocatalytic degradation of RR 24 dye followed pseudo-first-order kinetics, with a rate constant of 0.02944 min⁻¹. XRD analysis revealed a crystallite size of 8.92 nm. Thermodynamic parameters (ΔS°, ΔH°, and ΔG°) were measured at various temperatures, showing the endothermic and spontaneous nature of the reaction. Thus, the developed photocatalyst proves to be an excellent choice for eliminating this type of dye.