In situ enzymatic conversion of biomass into glucose in biodegradable enzyme compatible ionic liquids
Yang, Dong (2015) In situ enzymatic conversion of biomass into glucose in biodegradable enzyme compatible ionic liquids. PhD thesis, Dublin City University.
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This thesis is focused on the wood swelling, dissolution and regeneration in ionic liquids and cellulase digestibility after wood pretreatment in ionic liquids. Various ILs and their mixtures were used to swell wood chips of accurately measured linear dimensions. The change in the swelling of the wood chips was correlated to cellulase digestibility.
A series of novel chiral prolinate ionic liquids were designed, synthesized and characterized in order to measure their thermal stability, biodegradability and anti-microbial toxicity. The amino acids and natural alcohol derivatives (i.e. proline, trans-4-hydroxyl-proline and cis-4-hydroxyl-proline are raw materials for green synthesis of ionic liquids. Tetrabutyl ammonium hydroxide solution, tetraethyl ammonium hydroxide solution, tetrapropyl ammonium hydroxide solution and tetramethyl ammonium pentahydrate are the other starting materials for the ionic liquid synthesis. The synthesis of these ILs was carried out conveniently in one pot in air; a single-step, followed by purification. All the prolinate ILs made were in the thesis were characterized by a range of spectroscopic techniques including: 1H and 13C NMR, IR and HRMS. The biodegradability of 24 synthesized prolinate chiral ILs were analyzed by using with a wastewater microorganism the medium for the target chemicals. Antifungal activity of the 24 prolinate chiral ILs were determined against twelve fungal strains, and antimicrobial toxicity was determined against eight bacterial strains. All prolinated based chiral ILs were found to be low toxicity towards eight strains of bacteria and twelve strains of fungi. The effects of stereochemistry and cation structure on the toxicity also have been discussed.
A series prepared chiral prolinate ILs have also been applied in wood expansion, dissolution and regeneration. Cellulose and lignocellulose dissolution studies with ionic liquids have shown the ionic liquid cation plays a significant role, with the tetraalkylammonium prolinate series yielding good results for lignocellulose pretreatment, before enzymatic hydrolysis of the complex biomass structure.
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