Production of second-generation ethanol and carboxymethylcellulose from sugarcane bagasse pretreated with low-cost ionic liquids

Studies involving the use of residual biomass from processes have grown substantially. In this context, the efficiency of the production of second-generation ethanol and carboxymethylcellulose from sugarcane bagasse was evaluated in this work. Therefore, sugarcane bagasse was characterized and submitted to pretreatment with different low-cost ionic liquids [sec-butylammonium acetate (IL1); sec-butylammonium lactate (IL2); imidazolium acetate (IL3), and imidazolium lactate (IL4)]. After verifying the greater efficiency of the treatment performed with IL1, a new treatment was carried out with this ionic liquid. The pretreated material was subjected to enzymatic hydrolysis steps, modifying the hydrolysis time and the concentrations of treated sugar cane bagasse (%). The best pretreatment condition (63.8 h, 12.2% of pretreated bagasse, 50  °C, pH 4.8, enzyme concentration of 20 FPU.gram⁻¹ e, 250 rpm) enabled the conversion of pretreated sugarcane bagasse of 54.57 ± 0.28%. The sugarcane bagasse was submitted to the hydrolysis process using this condition, and the hydrolysate was used to the fermentation stage with a yield of 71.77% after 24 h. The residual holocellulose produced after hydrolysis produced a carboxymethylcellulose (CMC), making it possible to obtain it with a degree of substitution equal to 1.