Determination of Organic Impurities in Lignocellulosic Bioethanol Product by GC-FID

Abstract

In recent, production of bioethanol in Indonesia is produced primarily from sugarcane molasses and cassava as the 1st generation. But related with its development, it is quite hard to be a major feedstock in bioethanol conversion because there is conflict in using between consumption food and energy resources. Due to abundant lignocellulose biomass resources in Indonesia, such as empty fruit bunch (EFB) of oil palm, sugarcane bagasse and other forrest residue, the research in the development of process for 2nd generation bioethanol production is being increase. This case can be a right solution to solve the problem because lignocellulose is unused material. Processing of lignocellulosic biomass into bioethanol consists of four major unit operations: pre-treatment, hydrolysis, fermentation and product separation/distillation. Although ethanol is the dominant alcohol produced in the fermentation of sugars process, there are some byproducts in bioethanol product, such as organic impurities, water and organic acid. Determination of the impurity is important to prove the quality of produced bioethanol. Some of the impurities is not allowed in the product, such as methanol and others organic, that should be limited to control the performance from bioethanol as substituted fuel. Organic impurities of the bioethanol product was analyzed by using GC-FID while the water content was analyzed by using Karl Fischer Coulometric Moisture Titrator. In this research, the lignocellulosic bioethanol analyzed for the moisture content and organic impurities was undenatured one. The water content of the bioethanol sample was analyzed in 7 replicates where the average was 0.1776%-w (% RSD 2.0460). There are eight compounds of organic impurities detected in GC-FID that are acetaldehyde (0.0217%-w), acetone (0.0102%-w), ethyl acetate (0.0368%-w), methanol (0.0224%-w), isopropyl alcohol (0.0035%-w), n-propyl alcohol (0.0188%-w), isobutanol (0.0437%-w) and isoamyl alcohol (0.0377%-w).