Dissolution of rubber biomass in imidazoliumbased ionic liquid for regeneration of cellulose / Dazylah Darji

Darji, Dazylah (2016) Dissolution of rubber biomass in imidazoliumbased ionic liquid for regeneration of cellulose / Dazylah Darji. PhD thesis, University of Malaya.

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    Abstract

    Biomass is an organic material and important to utilize its chemical extraction as a source for renewable energy. In the present research, imidazolium-based ionic liquid as pretreatment solvent for extraction of the valuable chemical from rubber biomass was investigated. The conditions optimization was carried out by using different types of anions of imidazolium-based ionic liquids, temperature, various particle sizes of rubber biomass, rubber biomass loading in ionic liquids and different modes of heating (conventional and microwave). The effects of pretreatment parameter were studied on the chemical composition, cellulose crystallinity, surface morphology and enzymatic hydrolysis of the regenerated rubber biomass. The type of ionic liquids was found to have impacts on the dissolution yield of the rubber biomass. The results show that the mass regenerated yield of 1-ethyl-3-methylimidazolium acetate ([Emim] [OAc]) is 95% and indicates the most suitable solvent for rubber biomass solvation compared to 1- ethyl-3-methylimidazolium chloride ([Emim]Cl) (70%) by using the conventional and microwave heating methods. The optimum process pretreatment conditions for conventional dissolution heating were at the temperature of 110 oC and the particle size ranging from 10-50 μm. These conditions significantly enhanced the dissolution rate, regeneration yield and provided a higher conversion yield of cellulose to glucose. Comparing with conventional heating methods, dissolution of rubber biomass with microwave heating was attained at the lower dissolution time (2 minutes) and can be used as a potential alternative method to extract cellulose from rubber biomass. The physico-chemical analysis of the biomass properties such as the changes in the crystallinity was carried out by using field emission scanning electron microscopy (FESEM), Fourier Transform infrared (FTIR) and X-ray diffraction (XRD). From FESEM’s result, the smaller particle size (10–50 μm) displayed a disorganized structure iii and collapse of cell wall surfaces due to decreasing of cellulose crystallinity and the removal of lignin. The enhanced digestibility is attributed to the decrease of cellulose crystallinity as confirmed by FTIR and XRD analysis. The obtained cellulose was hydrolyzed by trichoderma reesei and cellobiase using HPLC which is resulting in a final glucose yield of 84 w/w % at the optimal condition for dissolution of rubber biomass (110 °C for 12 h at 5.0% solids loading). Recyclability of ionic liquid was also studied for evaluation of the economic efficiency of the pretreatment method. It was demonstrated that [Emim][OAc] can be recycled up to four times with 90% recovery and reused as a solvent for dissolution of rubber biomass. Thermogravimetric analysis (TGA) and Nuclear Magnetic Resonance (NMR) spectroscopy showed no structural changes in the recovered ionic liquids. This work has shown that ionic liquid can be a greener alternative towards the recovery of lignin and cellulose due to its excellent reusability.

    Item Type: Thesis (PhD)
    Additional Information: Thesis (Ph.D.) – Faculty of Science, University of Malaya, 2016.
    Uncontrolled Keywords: Rubber biomass; Organic materials; Energy renewal; Regeneration of cellulose
    Subjects: Q Science > Q Science (General)
    T Technology > T Technology (General)
    Divisions: Faculty of Science
    Depositing User: Miss Dashini Harikrishnan
    Date Deposited: 15 Nov 2016 12:08
    Last Modified: 15 Nov 2016 12:08
    URI: http://studentsrepo.um.edu.my/id/eprint/6557

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