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Facile, room-temperature pre-treatment of rice husks with tetrabutylphosphonium hydroxide: Enhanced enzymatic and acid hydrolysis yields
- Lau, B.B.Y., Luis, E.T., Hossain, M.M., Hart, W.E.S., Cencia-Lay, B., Black, J.J., To, T.Q., Aldous, L.
- Bioresource technology 2015 v.197 pp. 252-259
- acid hydrolysis, ambient temperature, aqueous solutions, biomass, cellulose, delignification, endo-1,4-beta-glucanase, enzymatic hydrolysis, glucose, lignin, rice hulls, silica, solubility, sulfuric acid
- Aqueous solutions of tetrabutylphosphonium hydroxide have been evaluated as pretreatment media for rice husks, prior to sulphuric acid hydrolysis or cellulase enzymatic hydrolysis. Varying the water:tetrabutylphosphonium hydroxide ratio varied the rate of delignification, as well as silica, lignin and cellulose solubility. Pre-treatment with 60wt% hydroxide dissolved the rice husk and the regenerated material was thus heavily disrupted. Sulphuric acid hydrolysis of 60wt%-treated samples yielded the highest amount of glucose per gram of rice husk. Solutions with good lignin and silica solubility but only moderate to negligible cellulose solubility (10–40wt% hydroxide) were equally effective as pre-treatment media for both acid and enzymatic hydrolysis. However, pre-treatment with 60wt% hydroxide solutions was incompatible with downstream enzymatic hydrolysis. This was due to significant incorporation of phosphonium species in the regenerated biomass, which significantly inhibited the activity of the cellulase enzymes.