Development of a Two-Step Hydrothermal Pretreatment for Sugarcane Bagasse Delignification Surpassing Acidic and Chemical Methods

Sugarcane bagasse (SCB), a plentiful underutilized agricultural residue holds great potential as a feedstock for biofuel and other chemical constituents’ production. In the current study, an eco-friendly two-step hydrothermal pretreatment approach was developed for efficient delignification of sugarcane bagasse, surpassing traditional acidic and chemical methods. Initially, sugarcane biomass underwent a mild hydrothermal treatment to open the lignin structure, followed by a cost-effective mechanical step to remove lignin effectively. The two-stage hydrothermal pretreatment strategy reduced 53.01% lignin and also increased the total available sugars by 1.71-fold from sugarcane biomass. In contrast, a lower level of lignin degradation was observed when the biomass was delignified with different alkali, acidic, and oxidative methods. Lignin degradation of 33.12%, 38.28%, 35.30%, and 33.04% was achieved during sulfuric acid, sodium hydroxide, sodium carbonate, and sodium chlorite pretreatment. The pretreatment efficacy was validated using various microscopic and spectroscopic techniques (FESEM, FTIR, and XRD). These findings suggest that a two-step hydrothermal process may provide a promising and eco-friendly alternative for the sustainable development of lignocellulosic biorefinery.