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Biodiesel, a promising alternative to traditional petroleum fuels, is a green energy solution. Photocatalysis is a facile, novel, economic, and efficient approach to biodiesel synthesis. Metal sulfides have been used extensively for various photocatalytic applications. The present study demonstrates, for the first time, the photocatalytic production of biodiesel using a novel metal sulfide‐based heterogeneous photocatalyst under visible light irradiation.A nano zero‐valent silver doped hydroxyapatite (Ag/HAp) was synthesized using a green bio‐reductant technique and decorated with tin sulfide nanoparticles (SnS2/Ag/HAp or SAH) for photocatalytic biodiesel synthesis. The hydroxyapatite (HAp) was extracted from waste fish scales to minimize the use of chemicals and to utilize waste for useful applications. The prepared SAH photocatalyst was characterized through X‐ray diffraction, UV‐visible diffuse reflectance spectroscopy, photoluminescence spectroscopy, Fourier transform infrared analysis, energy dispersive X‐ray analysis, scanning electron microscopy, high‐resolution transmission electron microscopy and X‐ray photoelectron spectroscopy analysis. The effect of reaction parameters was optimized, and under optimum conditions of 1 wt% photocatalyst loading, and 8:1 methanol‐to‐oleic‐acid ratio, for 60 min, a high yield of 98.0 ± 0.61% could be achieved using a SAH photocatalyst.Scavenger tests indicated the simultaneous generation of photoinduced electrons and holes necessary for photocatalytic biodiesel synthesis. A mechanism for the photocatalytic esterification reaction of oleic acid is proposed. The synthesized SnS2‐based photocatalyst could be easily recoverable and reusable for five consecutive runs, which can replace traditional industrial heterogeneous catalysts in the near future. [ABSTRACT FROM AUTHOR]

A novel Chitosan/Indium sulfide (CS/In2S3) nanocomposite was created by co-precipitating Chitosan and InCl3 in solution, resulting in In2S3 agglomeration on the Chitosan matrix with a remarkable pore diameter of 170.384 Å, and characterized it for the physical and chemical properties. Under optimal conditions (pH = 7, time = 60 min, catalyst dosage = 0.24 g L−1, and dye concentration = 100 mg L-1), the synthesized nanocomposite demonstrated remarkable adsorption capabilities for Victoria Blue (VB), attaining a removal efficiency of 90.81%. The Sips adsorption isotherm best matched the adsorption process, which followed pseudo-second-order kinetics. With a rate constant of 6.357 × 10–3 g mg−1 min−1, the highest adsorption capacity (qm) was found to be 683.34 mg g−1. Statistical physics modeling (SPM) of the adsorption process revealed multi-interaction and multi-molecular adsorption of VB on the CS/In2S3 surface. The nanocomposite demonstrated improved stability and recyclability, indicating the possibility for low-cost, reusable wastewater dye removal adsorbents. These results have the potential to have practical applications in environmental remediation. [ABSTRACT FROM AUTHOR]