Pretreatment of crop wastes from edible biomass with a protic ionic liquid

The use of protic ionic liquids (PILs) in biomass processing has attracted significant attention in the recent years due to their synthesis in a relatively cheaper and easier way in comparison with their aprotic counterparts. In this study, PIL, triethylammmonium hydrogen sulfate (TEAHSO4) was explored in terms of its effects on the deconstruction of industrial crop wastes; corn cob, corn husk and wheat bran. Characterization of the pretreated biomass samples via scanning electron microscopy (SEM) and compositional analysis demonstrated structural changes and improvements in the cellulose content of the biomass. TEAHSO4 led to favorable modifications in the composition of wheat bran. It enhanced cellulose content of wheat bran from 40% to 60%, through removal of 67% of the lignin present in the biomass. Pretreated biomass samples were evaluated in terms of their conversion to glucose. At the 24th hour of the enzymatic reaction, cellulose in the pretreated corn cob, corn husk and wheat bran samples were converted into glucose with roughly 85%, 71% and 96% yields, respectively. TEAHSO4 pretreatment enhanced the enzymatic accessibility of wheat bran almost 10-fold. Ionic liquid media recovered following the pretreatments were analyzed for their content regarding the platform chemicals; 5-hydroxymethylfurfural (5- HMF) and levulinic acid (LA). The highest yield for 5-HMF was obtained as 47% in the ionic liquid medium obtained upon TEAHSO4 pretreatment of corn husk. On the other hand, corn cob pretreatment resulted in the highest LA yield which was 93%.