Visible light driven g-C3N4 photocatalytic pretreatment of rice straw for enhanced biogas production

Abstract

This study investigates the utilization of Graphitic Carbon Nitride (g-C₃N₄) as a photocatalytic material for enhancing biofuel production from rice straw, an agricultural residue with potential for sustainable energy generation. The melamine-synthesized g-C₃N₄ is used as a pretreatment agent, where rice straw is immersed in a g-C₃N₄ solution and exposed to 450-600 nm solar irradiation for varying durations. This pretreatment process modifies the biomass structure, resulting in a reduction of the silica content to 72.05% and an increase in the carbon percentage to 41.58% within the rice straw. Methane production demonstrates the effectiveness of g-C₃N₄-based pretreatment, with methane production from raw rice straw at 231 mL/g_VS. Co-digestion with waste activated sludge increases methane production to 507 mL/g_VS, while a 3 h pretreatment further enhances it to 547.16 mL/g_VS, and a 6 h pretreatment leads to 595.5 mL/g_VS. Comprehensive characterization techniques confirm the successful modification of biomass structure using g-C₃N₄.