Studies on the third generation of Ionic liquids - Halophillic Cellulase system for Lignocellulose hydrolysis

• Main Author: Ahmad Anas, Nagoor Gunny
• Other Authors: Assoc. Prof. Dr. Dachyar Arbain
• Format: Thesis
• Language: English
• Published: Universiti Malaysia Perlis (UniMAP) 2019
• Subjects: Lignocelluloses; Lignocellulosic biomass; Biomass; Ionic Liquids (ILs); Lignocellulosic biomass > Product
• Online Access: http://dspace.unimap.edu.my:80/xmlui/handle/123456789/59825

The conversion of lignocellulosic biomass into value-added products requires pretreatment, hydrolysis (saccharification) and the conversion of simple sugar into end products. The limiting factor of these three processes lies in the pre-treatment steps. Conventional pre-treatment methods normally use strong acids or alkali which pose environmental problems. Recently pre-treatment using the third generation of Ionic Liquids (ILs), also known as Deep Eutectic Solvents (DESs) has been considered green and cost-effective. However, the main drawback of DESs pre-treatment is that it is not fully compatible with the enzyme required in saccharification. This compatibility issue was addressed in the present study by producing a salt tolerant enzyme (halophilic enzyme) and formulating low viscosity, thermal stable DES. The halophilic enzyme was produced from a newly isolated halophilic fungus, identified as Aspergillus terreus UniMAP AA-6; DESs were synthesized and screened using choline chloride as a hydrogen bond acceptor and selected carboxylic acids and polyol alcohols as hydrogen bond donors. The compatibility between halophilic cellulase and DESs was evaluated by monitoring the stability of halophilic cellulase in the presence of various concentrations of commercial ILs and DESs. The applicability of the DES-cellulase system for lignocelluloses hydrolysis was evaluated based on glucose production, energy consumption and kinetic performance. It was found that halophilic cellulase showed higher stability in the presence of 10% (v/v) ILs and also was stable and retained 90 % of its original activity in the presence of 10% (v/v) DESs. The DESs- Cellulase system exhibited higher glucose percentage enhancement and lower energy consumption as compared to diluted alkali system, while in terms of kinetic performance, DES exhibited good kinetic performance, which reflects the ability of DESs to serve as good saccharification media for the DESs-cellulase system. Finally, with regard to glucose production, rice husk treated with DESs-halophilic cellulase system were as good as the typical IL pre-treatment method but with extra benefits in terms of cost and environmental aspects. These findings have demonstrated a better approach for the in situ saccharification of DESs pre-treated lignocelluloses.