Abstract

Many pretreatment techniques were used to change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates for conversion to fuel. A hydrothermal (HT) combined chemical treatment (acid or alkaline) and steam explosion (SE) at various pretreatment conditions were applied on bamboo biomass to study the hydrolysis of hemicelluloses and celluloses to their corresponding reducing sugars and evaluated these hydrolysis yield process. The results showed that the yield of pretreatment using sulfuric acid is more effective than using sodium hydroxide at the same hydrothermal condition. By treatment raw bamboo in 1.2% sulfuric acid, at 121 °C for 60 min and ratios of 1:15 (g/mL), the hydrolysis yield was 20%, exceeding than 10% that in 2.5% NaOH. Consecutive immersed in H₂SO₄ for 24 h before the steam explosion at 230 °C in 3 min, hydrolysis efficiency significantly increased to 72% compared to other methods. Whereas treated in NaOH then steam exploding, the cellulose and hemicellulose were not strongly affected to increase soluble sugars. Alkaline pretreatment in HT or SE conditions had extracted lignin the most of over 39%. The inhibitory concentration of furfural in the hydrolysate of immersed sulfuric acid and steam explosion showed the highest value of 0.402 g/L.

Graphic Abstract

In this study, bamboo biomass was carried out two pretreatment processes including hydrothermal and steam explosion with variations of acid and alkaline conditions. The carbohydrate content and dissolved sugar content in bamboo biomass were determined via HPLC-RID analysis technique to investigate the effect of conditions and processes on hydrolysis. The results prove that treated biomass by sulfuric acid then steam exploding is remarkably effective process that can be applied to large-scale for bamboo biomass.