The Effects of Mild Alkaline Pretreatment on the Enzymatic Hydrolysis of Eucalyptus pellita Wood

Abstract

In this study, a dilute alkaline pretreatment (sodium carbonate and calcium hydroxide mixture) was evaluated for saccharification of extruded Eucalyptus wood. The hydroxide ions produced by the alkaline combination is remarkably more effective than using the alkaline compounds individually. Three critical factors for the simultaneous pretreatment and saccharification process, such as the pretreatment time, temperature, and molar concentration of Na₂CO₃:Ca(OH)₂, were optimized to maximize bio sugar yield. The results show that although the lignin amount of hardwoods (i.e., Eucalyptus ) is high (34.8%), but it is possible to overcome the recalcitrant of wood and improve glucose yields by employing this combined pretreatment (mechanical and chemical). The results also show that the glucose conversion by the enzyme was improved by approximately 14% for every 10% increase in delignification rate. However, simultaneously, the yield of glucose was reduced by approximately 7% during every 10% increase in delignification rate during alkaline pretreatment. This study indicated that mild sodium carbonate and calcium hydroxide pretreatment effectively reduced biomass recalcitrance and subsequently improved the digestibility of lignocellulosic biomass.