Dilute acid pretreatment of starch-containing rice hulls for ethanol production
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Yoney López
Abstract
Rice hulls are potential low-cost feedstocks for fuel ethanol production in many countries. Most of the relevant publications are devoted to homogenous (high quality) hulls generated in industrial mills. On the other hand, small-scale mills give rise to hulls containing grain fragments and bran. In the present work, the dilute-acid pretreatment of such heterogeneous rice hulls was investigated based on a central composite rotatable experimental design. The variables were: temperature (140–210°C), biomass load (5–20%), and sulfuric acid concentration (0.5–1.5% based on reaction mixture). A total of 16 experimental runs were carried out, including a 23-plan, two replicates at the central point and six star points. Low temperatures were found to be favorable for the hydrolysis of xylan and of the easily hydrolyzable glucan fraction. High glucose formation (up to 15.3% of the raw material dry weight), attributable to starch hydrolysis, was detected in the hydrolysates obtained under the least severe pretreatment conditions. Several models were developed for predicting the effect of the operational conditions on the yield of pretreated solids, xylan and glucan conversion upon pretreatment, and on enzymatic convertibility of cellulose. The pretreatment temperature exerted the most significant effect on the conversion of the polysaccharides. Optimum results were predicted for the conversion of easily-hydrolyzable glucan in the material pretreated at 140.7°C, and for the enzymatic saccharification of cellulose in the material pretreated at 169°C. These results are interpreted that a two-step acid hydrolysis may be the best pretreatment strategy for heterogeneous rice hulls produced in small mills.
©2011 by Walter de Gruyter Berlin Boston
Articles in the same Issue
- Editorial
- EWLP 2010, 16th–19th August 2010, Hamburg, Germany
- Review
- Bio based fuels and fuel additives from lignocellulose feedstock via the production of levulinic acid and furfural
- Original Papers
- Optimization of steam pretreatment conditions for enzymatic hydrolysis of poplar wood
- Fungal pretreatment of pine wood to reduce the emission of volatile organic compounds
- Dilute acid pretreatment of starch-containing rice hulls for ethanol production
- Studies of the chemoenzymatic modification of cellulosic pulps by the laccase-TEMPO system
- Development of an integrated thermal and enzymatic hydrolysis for lignocellulosic biomass in fixed-bed reactors
- A larch based biorefinery: pre-extraction and extract fermentation to lactic acid
- Lignins as agents for bio-protection of wood
- Isolation and characterization of the phenolic fractions of wood pyrolytic oil
- Purification of Eucalyptus globulus water prehydrolyzates using the HiTAC process (high-temperature adsorption on activated charcoal)
- Disintegration and dissolution kinetics of wood chips in ionic liquids
- Ionic liquids as media for biomass processing: opportunities and restrictions
- Autohydrolysis of birch wood
- Solvent extraction as a means of preparing homogeneous lignin fractions
- Conditioning of SO2-ethanol-water spent liquor from spruce for the production of chemicals by ABE fermentation
- Total mass balances of SO2-ethanol-water (SEW) fractionation of forest biomass
- Lignin oxidation mechanisms under oxygen delignification conditions. Part 1. Results from direct analyses
- Lignin oxidation mechanisms under oxygen delignification conditions. Part 2: Advanced methods for the detailed characterization of lignin oxidation mechanisms
- Lignin oxidation mechanisms under oxygen delignification conditions. Part 3. Reaction pathways and modeling
- Simplified determination of total lignin content in kraft lignin samples and black liquors
- Xylan deposition onto eucalypt pulp fibers during oxygen delignification
- Dissolution of dissolving pulp in alkaline solvents after steam explosion pretreatments
- Structure and antioxidant activity of diarylheptanoids extracted from bark of grey alder (Alnus incana) and potential of biorefinery-based bark processing of European trees
- Short Note
- Binding affinities of different metal ions to unbleached hardwood kraft pulp
- Meetings
- Meetings
Articles in the same Issue
- Editorial
- EWLP 2010, 16th–19th August 2010, Hamburg, Germany
- Review
- Bio based fuels and fuel additives from lignocellulose feedstock via the production of levulinic acid and furfural
- Original Papers
- Optimization of steam pretreatment conditions for enzymatic hydrolysis of poplar wood
- Fungal pretreatment of pine wood to reduce the emission of volatile organic compounds
- Dilute acid pretreatment of starch-containing rice hulls for ethanol production
- Studies of the chemoenzymatic modification of cellulosic pulps by the laccase-TEMPO system
- Development of an integrated thermal and enzymatic hydrolysis for lignocellulosic biomass in fixed-bed reactors
- A larch based biorefinery: pre-extraction and extract fermentation to lactic acid
- Lignins as agents for bio-protection of wood
- Isolation and characterization of the phenolic fractions of wood pyrolytic oil
- Purification of Eucalyptus globulus water prehydrolyzates using the HiTAC process (high-temperature adsorption on activated charcoal)
- Disintegration and dissolution kinetics of wood chips in ionic liquids
- Ionic liquids as media for biomass processing: opportunities and restrictions
- Autohydrolysis of birch wood
- Solvent extraction as a means of preparing homogeneous lignin fractions
- Conditioning of SO2-ethanol-water spent liquor from spruce for the production of chemicals by ABE fermentation
- Total mass balances of SO2-ethanol-water (SEW) fractionation of forest biomass
- Lignin oxidation mechanisms under oxygen delignification conditions. Part 1. Results from direct analyses
- Lignin oxidation mechanisms under oxygen delignification conditions. Part 2: Advanced methods for the detailed characterization of lignin oxidation mechanisms
- Lignin oxidation mechanisms under oxygen delignification conditions. Part 3. Reaction pathways and modeling
- Simplified determination of total lignin content in kraft lignin samples and black liquors
- Xylan deposition onto eucalypt pulp fibers during oxygen delignification
- Dissolution of dissolving pulp in alkaline solvents after steam explosion pretreatments
- Structure and antioxidant activity of diarylheptanoids extracted from bark of grey alder (Alnus incana) and potential of biorefinery-based bark processing of European trees
- Short Note
- Binding affinities of different metal ions to unbleached hardwood kraft pulp
- Meetings
- Meetings
