Biorefining of lignocellulosic feedstock and waste materials using ionic liquid

Abstract

The ionic liquid trihexyltetradecylphosphonium hydrogen sulphate (THTDP HSO4) was used to extract cellulose from various lignocellulosic sources:- wheat straw, perennial ryegrass, willow, anaerobic digestate (AD) and spent mushroom compost (SMC). This was compared with a traditional dilute sulphuric acid extraction to evaluate the potential for this ionic liquid to be of use in the biorefining industry. The use of ultrasonication to facilitate the reaction was also tested. Results showed that this ionic liquid, which combines the features of a hydrophobic solvent with an acidic catalyst was effective in hydrolysing lignocelluloses. Compared to the use of dilute sulphuric acid, the ionic liquid produced purer, more thermally stable cellulosic fibres. It was also shown to be as effective as the dilute sulphuric acid in pretreating lignocelluloses for enzymatic hydrolysis. Finally, ultrasonication was shown to be compatible with the ionic liquid and suggests an energy efficient method for pretreatment of lignocellulose.