Lignocellulosic biomass is composed of cellulose, hemicellulose and lignin which are not readily available for conversion in their native form. It is widely accepted that lignin acts as the glue that binds cellulose and hemicellulose, giving rigidity and resistance to lignocellulose. The use of non-ionic surfactants during pretreatment can help alter the structure of lignocellulosic biomass to improve cellulose digestibility and ethanol yields.
Tween 80, Tween 20, PEG 4000, or PEG 6000 was used with ammonium hydroxide for the pretreatment of sugarcane bagasse. The pretreatment was carried out by mixing sugarcane bagasse, ammonium hydroxide (28% v/v) and water at a ratio of 1: 0.5: 20, adding 3% (w/w) surfactant based on the weight of dry biomass, and heating the mixture to 160 °C for 1 h. The final concentration of ammonium hydroxide was 0.65% w/w at 4.7% solids loading. Chemical compositions were determined before and after pretreatment. Fibers were hydrolyzed using commercial enzymes, Spezyme CP and Novozyme 188. Fermentable sugars and ethanol concentrations were analyzed by HPLC. The results indicated that PEG 4000 and Tween 80 gave the highest cellulose digestibilities (62%, 66%) and ethanol yields (73%, 69 %), respectively.
Tween 80 was selected over PEG 4000 because of its low cost. The effect of two concentrations of ammonium hydroxide 0.26% w/w (1: 0.2: 20, biomass: ammonium hydroxide: water ratio) and 0.65% w/w (1: 0.5: 20, biomass: ammonium hydroxide: water ratio), and Tween 80 (1.5%, 3% and 5% w/w, based on the weight of dry biomass) were evaluated during pretreatment at 4.7% solids loading. The greatest lignin removal (37%), cellulose digestibility (66%) and hemicellulose digestibility (43%) were observed at 1: 0.5: 20 ratio supplemented with 3% (w/w) Tween 80. These pretreatment parameters were selected for scale-up experiments at a higher solids loading (10.5%) in a 20 L bioreactor. The greatest lignin removal (55%), cellulose digestibility (72%) and hemicellulose digestibility (57%) were observed with 3% Tween 80-dilute ammonia pretreatment at 1: 0.5: 8 ratio with a final concentration of ammonium hydroxide of 1.47% w/w. Morphological changes in the structure of non-ionic surfactant-dilute ammonia pretreated sugarcane bagasse were observed.
| Identifer | oai:union.ndltd.org:LSU/oai:etd.lsu.edu:etd-11112012-190037 |
| Date | 20 November 2012 |
| Creators | Cao, Shuo |
| Contributors | Aita, Giovanna, Finley, John, King, Joan |
| Publisher | LSU |
| Source Sets | Louisiana State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lsu.edu/docs/available/etd-11112012-190037/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached herein a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to LSU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below and in appropriate University policies, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0014 seconds