Pretreatment of Leucaena Leucocephala Using Deep Eutectic Solvent for Ethanol Production by Kluyveromyces Marxianus UniMAP 1–1

Conventional pretreatment methods such as alkaline and acid pretreatment which were used in biorefineries to dissolve lignin and hemicellulose faces many drawbacks. These pretreatment methods were considered as toxic not only to the environment, but also to the biomass as further treatment using these solvents will lead to the production of hydroxymethyl furfural (HMF) and furfural, which can inhibit the production of ethanol. Recently, deep eutectic solvents (DES) have grown in popularity as an alternative solvent to substitute conventional pretreatment solvents. DES have a great number of advantages such as biodegradability, non-toxic, low volatility and low cost. Furthermore, DES also is a powerful solvent to dissolve lignin, thus this makes DES a superior solvent to be used in biorefineries compared to alkaline and acid pretreatment. In this study, Leucaena leucocephala seeds and pods were treated with choline chloride – glycerol (ChCl – Gly) based DES at 1:2 molar ratio, and the performance subjected to sugar released and ethanol production were analyzed using high performance liquid chromatography (HPLC). The values were then compared with the conventional pretreatment methods as the controls. The results suggested that DES pretreatment released slightly higher total sugar, 29.28 g/L compared to alkaline and acidic pretreatment at 28.77 and 24.94 g/L, respectively. On the other hand, the yield of ethanol after fermentation in DES treatment were among the highest, which was 0.287 g ethanol/g glucose with 56.27% conversion compared to theoretical yield. The purpose of this report is to offer further information in the interest of making DES as a good replacement for the conventional pretreatment method.