One-Pot Microwave-Assisted Hydrolysis of Cellulose and Hemicellulose in Selected Tropical Plant Wastes by NaOH-Freeze Pretreatment

In this work, in order to achieve one-pot hydrolysis of cellulose and hemicellulose in lignocellulosic biomass, freeze pretreatment with 0–5 wt % NaOH (3 wt% was chosen as the best concentration) and subsequent microwave-assisted dilute sulfuric acid hydrolysis were applied to tropical plant wastes. Single factor optimization of hydrolysis of the pretreated bagasse was studied, and the best conditions (140 °C, 30 s, substrate/solvent ratio of 1/60 and 0.4 M H₂SO₄) were further applied to Jatropha and Plukenetia hulls. Under the best conditions, yields of sugars from cellulose (glucose) and hemicellulose (xylose, mannose, and arabinose) in the pretreated bagasse were 84.0% and 92.7%, enhanced by 273.4% and 59.3% as compared with untreated sample, respectively. For the pretreated Jatropha and Plukenetia hulls, yields of glucose and hemicellulose sugars were 85.7% and 93.3% (increased by 225.9% and 75.4%) and 85.0% and 92.9% (increased by 214.8% and 81.4%), respectively.