Integrated photocatalytic Process for Lactic Acid synthesis from Sugarcane Leaf (Saccharum officinarum): Biomass delignification and photocatalytic Conversion with oxygen-doped graphitic carbon nitride

Background: Photocatalytic upcycling of agro-biomass represents an advanced approach for simultaneously producing high-value products and managing organic waste. However, its commercial viability remains suboptimal, primarily due to challenges in developing efficient photocatalysts. The regulation and optimization of photocatalyst performance play a crucial role in enhancing biomass conversion efficiency and improving platform chemical production. Methods: This study investigates the efficiency of microwave-assisted seawater treatment for lignin fractionation from Saccharum officinarum leaf (SCL) biomass and its integration with high-value organic acid synthesis in a photobiorefinery framework. The treatment using seawater with sodium carbonate (SW-SC) exhibited superior fractionation performance, yielding 79.20 wt % cellulose in the treated SCL biomass (TSCL), which is enhancing its suitability for further conversion. Various oxygen-doped g-C₃N₄ photocatalysts were synthesized through oxygen coupling, among the g-C₃N₄-O_{50 %} exhibiting the highest photocatalytic activity. Under alkaline conditions, the photocatalytic conversion of TSCL resulted in a maximum lactic acid (LA) yield of 345.39 mg g⁻¹ TSCL and a formic acid (FA) yield of 30.45 mg g⁻¹ TSCL. Significant Findings: The one-thousand-fold scale-up experiment demonstrated the feasibility of industrial lactic acid production using this reaction system, considering its favorable reaction conditions, economic viability, and environmental benefits. This study introduces a novel photocatalytic approach for the selective oxidation of biomass-derived monosaccharides into lactic acid.