A mild and efficient pretreatment strategy for the high-value utilization of cellulose derived from Sargassum spp

Algae are pivotal in biofuel production, with pretreatment serving as a crucial step in the process. Traditional methods predominantly rely on strong acids, bases, or high temperatures, which contradict the principles of green and sustainable development. To overcome these challenges, this study optimized a novel chemical pretreatment method for Sargassum spp. using ultrasound-assisted KMnO₄ and Na₂SO₃ at 20-60 °C. Key parameters, including reagent concentration, temperature, and reaction time, were refined, with optimal conditions established at 40 °C for 4 h. Ultrasound improved reagent permeability, while KMnO₄ and Na₂SO₃ disrupted the biomass structure through redox reactions. The cellulose content in the residual biomass increased from 11.99 wt% to 23.88 wt%, while AIR content decreased to 15.96 wt%. The maximum cellulose enzyme accessibility reached 19.56 mg/g. Compared to conventional methods, the glucose yield from Sargassum spp. hydrolysis increased from 51.62 mg/g to 107.75 mg/g, and ethanol yield from fermentation rose from 24.61 mg/g to 50.90 mg/g. This study presents a simple, cost-effective, efficient, and environmentally friendly pretreatment method for algal biomass, highlighting its significant industrial potential.