Comparative analysis of pretreatment methods on sorghum (Sorghum durra) stalk agrowaste for holocellulose content

摘要

This study compares different types of pretreatment methods, such as thermal pretreatment at 120 degrees C, autoclaving, microwaving and ultrasonication in the presence of water, dilute acid (1% H2SO4) or dilute alkali (1% NaOH) on Sorghum stalk with respect to the holocellulose and Acid Detergent/Insoluble Lignin content. Among all the methods, pretreatment with 1% NaOH along with autoclaving at 121 degrees C and 15psi for 30min was the most effective method for Sorghum stalk. Fourier Transform Infra-Red spectroscopy analysis of this pretreated biomass showed the removal of lignin and Field Emission Scanning Electron Microscope analysis displayed enhanced surface roughness. The enzymatic hydrolysis of raw and best pretreated Sorghum stalk using recombinant endo--1,4-glucanase (CtCel8A) and -1,4-glucosidase (CtBgl1A) both from Clostridium thermocellum gave glucose yields, 22.4mg/g raw biomass and 34mg/g pretreated biomass, respectively, resulting in 1.5-fold increase of glucose yield after the pretreatment.