Effect of water of crystallization on the dissolution efficiency of molten zinc chloride hydrate salts during the pre-treatment of corncob biomass

Abstract

BACKGROUND Agro-wastes albeit abundant and cheap, require pre-treatment steps tailored to overcome the characteristic recalcitrance of lignocellulosic biomass. In this study, zinc chloride hydrate salts were studied for their biomass deconstruction potential. The role of salts' hydration and to what degree it affects the dissolution efficiency was evaluated. Milled corn cobs from local farmlands were dissolved in the following solvent systems; ZnCl2.3H2O, ZnCl2 .4H2O, ZnCl2 .5H2O and ZnCl2 .7H2O at 70 °C for 60 mins at a biomass to solvent ratio of 1:12. RESULTS The difference between the least and most hydrated solvent systems in terms of total released sugars as a percentage of recoverable sugar is 70.1%. The ZnCl2.4H2O solvent system extracted up to 49.1% of glucose and 95% of xylose. There were significant differences in the crystallinity indices and surface morphologies between the untreated and treated biomass. CONCLUSION The findings as documented contribute to current insights on the mechanisms of disintegration of lignocellulosic biomass in molten hydrate salts. The extraction of sugar components of biomass by ZnCl2.4H2O solvation was about 43% glucan and 99% xylan. © 2017 Society of Chemical Industry