Evaluation of the activated charcoals and adsorption conditions used in the treatment of sugarcane bagasse hydrolysate for xylitol production
| Autor: | A. Pessoa Júnior, J. B. Almeida e Silva, J. M. Marton, Maria das Graças de Almeida Felipe |
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| Jazyk: | angličtina |
| Rok vydání: | 2006 |
| Předmět: |
General Chemical Engineering
Lignocellulosic biomass Xylose Xylitol Hydrolysate chemistry.chemical_compound Hemicellulosic hydrolysate medicine Factorial design Food science lcsh:Chemical engineering Powdered activated charcoal Waste management lcsh:TP155-156 food and beverages sugarcane bagasse carbohydrates (lipids) Activated charcoal chemistry Fermentation Bagasse Activated carbon medicine.drug Overlaying plot |
| Zdroj: | Brazilian Journal of Chemical Engineering, Volume: 23, Issue: 1, Pages: 21-9, Published: MAR 2006 Brazilian Journal of Chemical Engineering v.23 n.1 2006 Brazilian Journal of Chemical Engineering Associação Brasileira de Engenharia Química (ABEQ) instacron:ABEQ Scopus-Elsevier Brazilian Journal of Chemical Engineering, Vol 23, Iss 1, Pp 9-21 (2006) |
| Popis: | Xylitol has sweetening, anticariogenic and clinical properties that have attracted the attention of the food and pharmaceutical industries. The conversion of sugars from lignocellulosic biomass into xylitol by D-xylose-fermenting yeast represents an alternative to the chemical process for producing this polyol. A good source of D-xylose is sugarcane bagasse, which can be hydrolyzed with dilute acid. However, acetic acid, which is toxic to the yeast, also appears in the hydrolysate, inhibiting microbe metabolism. Xylitol production depends on the initial D-xylose concentration, which can be increased by concentrating the hydrolysate by vacuum evaporation. However, with this procedure the amount of acetic acid is also increased, aggravating the problem of cell inhibition. Hydrolysate treatment with powdered activated charcoal is used to remove or decrease the concentration of this inhibitor, improving xylitol productivity as a consequence. Our work was an attempt to improve the fermentation of Candida guilliermondii yeast in sugarcane bagasse hydrolysate by treating the medium with seven types of commercial powdered activated charcoals (Synth, Carbon Delta A, Carbon Delta G, Carbon 117, Carbon 118L, Carbon 147 and Carvorite), each with its own unique physicochemical properties. Various adsorption conditions were established for the variables temperature, contact time, shaking, pH and charcoal concentration. The experiments were based on multivariate statistical concepts, with the application of fractional factorial design techniques to identify the variables that are important in the process. Subsequently, the levels of these variables were quantified by overlaying the level curves, which permitted the establishment of the best adsorption conditions for attaining high levels of xylitol volumetric productivity and D-xylose-to-xylitol conversion. This procedure consisted in increasing the original pH of the hydrolysate to 7.0 with CaO and reducing it to 5.5 with H3PO4. Next, the hydrolysate was treated under adsorption conditions employing CDA powdered activated charcoal (1%) for 30 min at 60ºC, 100 rpm and pH 2.5. The optimized xylitol volumetric productivity (0.50 g/L h) corresponded to a D-xylose-to-xylitol conversion of 0.66 g/g. |
| Databáze: | OpenAIRE |
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