Title:
Hydrolysis of Sunflower Stalks Using Nitric, Phosphoric and Sulphuric Acids
Author(s):
Martinez, M.L., Sánchez, S., Bravo, V.
Document(s):
Paper
Abstract:
The total or partial solubilization of the hemicellulose or cellulose fractions of sunflower stalks by acid hydrolysis can provide a sugar solution. The subsequent fermentation of these hydrolysates by microorganisms, which are capable of fermenting both hexoses and pentoses, can give rise to bioproducts of industrial interest, such as ethanol and xylitol. The aim of this work was to analyze, in a comparative manner, the effect that different concentrations of nitric, sulphuric and phosphoric acids may exert in the hydrolysis of sunflower-stalks, considering the conversions of hemicellulose and cellulose fractions, D-glucose yields, total reducing-sugars yields, and hydrolysis rates. The hydrolysis was carried out in a stirred batch reactor of 1 dm3 capacity, with 50 g of sunflower-stalk, a liquid/solid relationship of 20, and a temperature of 372 K. The nitric acid concentrations (CAo) were varied in the interval 0.0-2.0 M. In case of phosphoric acid, concentrations were modified in the range of 0.0-2.67 M and for sulphuric acid between 0.0-5.0 M. The hydrolysis time was 240 min and agitation 200 rpm. The results showed that the hydrolysis of the hemicellulose fraction was almost complete at a phosphoric acid concentration of 2.67 M, complete for concentrations of nitric acid 0.3 M and sulphuric acid 0.5 M. The percentage of converted cellulose also increased with the acid concentration, reaching a value of 13.9% with phosphoric acid 2.67 M and 36.6% with nitric acid 2 M. In the case of sulphuric acid, it was necessary to supply an acid concentration 2.5 M, to reach the maximum value in the conversion of the cellulose fraction. The analysis of the hydrolysis kinetic, by the proposed model, has allowed determine a reaction order of 1.3.
Keywords:
acid hydrolysis, sunflower stalks, nitric acid, D-xylose, D-glucose, phosphoric acid, sulphuric acid
Topic:
Biomass Conversion Technologies for Heating, Electricity and Chemicals
Subtopic:
Recycling of conversion residues (session 2)
Event:
19th European Biomass Conference and Exhibition
Session:
VP2.8.6
Pages:
1858 - 1861
ISBN-13:
978-88-89407-55-4
ISBN-10:
88-89407-55-7
Paper DOI:
10.5071/19thEUBCE2011-VP2.8.6
Price:
FREE
