Comparison of the Deep Euteutic Solvent (DES) Solvent for Extracting Lignin from the Lignocellulosic Material of Pineapple Leaves

Background: Lignocellulosic biomass is one of the materials that has the potential to produce cellulose. Lignocellulose material consists of lignin, hemicellulose and cellulose so that the three materials must be separated first to get pure cellulose. The main problem faced in the process of separating cellulose is the difficulty of separating lignin. One of the processes in separating lignin is by pretreatment of lignocellulosic material. Methods: In this study, Deep Euteutic Solvent (DES) choline (ChCl) as a hydrogen bond acceptor was synthesized and eight hydrogen bond donors (HBD) were mixed. Eight types of DESs, i.e. , choline chloride-acetic acid (ChCl-AA), ChCl: formic acid (ChCl-FA). ), choline chloride: Lactic acid (ChCl-LA), choline chloride:Citric acid (ChCl-SA), choline chloride: Glycerol (ChCl-G), choline chloride: Ethylenglycol (ChCl-EG), choline chloride: Sorbitol (ChCl-S), and choline chloride: Urea (ChCl -U) with a ratio of 1: 2 were investigated. Each. DES solvent was applied as a pretreatment for the lignocellulosic material of pineapple leaves. The results of the pretreatment formed were characterized by the Infra Red spectroscopic method to determine the typical functional groups. Result: The results showed that the pretreatment process using DES solvent resulted in a decrease in lignin levels in pineapple leaf powder, the highest in DES with linear saturated acid-based HBD, formic acid at 32.05%, glycerol at 30.18% and then in alpha hydroxy-based HBD, acetic acid at 29.90%. Meanwhile, the FT-IR results show that ChCl-FA has a high delignification ability during pretreatment. Pineapple leaves that have been pretreted with DES solvent can be a potential raw material for the next conversion process. This study presents DES as an effective and easy pretreatment method for lignin extraction.