Hydrolytic pretreatment of softwood and almond shells. Degree of polymerization and enzymatic digestibility of the cellulose fraction
- Univ. Rovira i Virgili, Tarragona (Spain)
Autohydrolysis and dilute-acid hydrolysis were used as pretreatment methods to enhance the enzymatic digestibility of cellulose in two different lignocellulosic substrates, a softwood mixture and an agricultural residue of almond shells. The changes in the chemical composition of the softwood mixture during dilute-acid pretreatment were studied, and the results were grouped by using a severity parameter, KR{sub OH}, which was derived from the kinetics of hemicellulose solubilization. The average degree of polymerization of the cellulose retained in the pretreated substrate, DP{sub v}, was investigated and its trend compared with that of almond shells. Cellulose DP{sub v} decreased for both the substrates from a value of 700 for the untreated lignocellulosic to around 200, which corresponds to the leveling-off degree of polymerization, as there is no significant variation in DP{sub v} when severity increases. Glucose yields after enzymatic saccharification of the pretreated substrates turned out to be higher for almond shells than for the softwood mixture, which had a very low susceptibility to enzymatic hydrolysis throughout the spectrum of experimental conditions investigated. At KR{sub OH} = 15,000, the glucose yield for the softwood mixture is 44% of the potential fraction present in the pretreated pulp, while for almond shells the maximum yield surpasses 97% for KR{sub OH} = 3. The different behavior these lignocellulosic species is not caused by different degrees of cellulose depolymerization nor by the removal of different amounts of carbohydrates during pretreatments in equivalent conditions.
- Sponsoring Organization:
- Comision Interministerial de Ciencia y Tecnologia (Spain)
- OSTI ID:
- 458454
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 36, Issue 3; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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