Sustainable oxidative desulfurization of fuel via lignin-derived heterogeneous catalysis: Optimized by Box-Behnken...

This study evaluates the oxidative desulfurization of dibenzothiophene (DBT) in model fuel using Kraft lignin-functionalized sulfur-doped graphitic carbon nitride (KL@S-g-C₃N₄), an eco-friendly heterogeneous photocatalyst. The photocatalyst's formation was confirmed through Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, photoluminescence (PL), UV-visible spectroscopy, X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA) analyses, Brunauer-Emmett-Teller (BET), field revealing successful adsorption of Kraft lignin onto S-g-C₃N₄. The functional groups of lignin enhanced interfacial interactions, active site availability, and dispersion of S-g-C₃N₄, while synergistic effects improved optical absorption and catalytic reactivity. Process optimization via Box-Behnken design (BBD) identified catalyst dosage (0.05 g), reaction time (37.5 min), and temperature (40 °C) as optimal parameters, achieving 98.1 % sulfur removal (200 ppm initial concentration) with 1 mL H₂O₂. Statistical validation through ANOVA confirmed the quadratic model's reliability (R² = 0.98) and non-significant lack of fit (p = 0.95). The photocatalyst retained structural integrity and performance over five reuse cycles, demonstrating robust durability. These findings position KL@S-g-C₃N₄ as a sustainable, efficient photocatalyst for desulfurization processes, combining enhanced catalytic activity with environmental compatibility.