Search results for "Autohydrolysis"
showing 7 items of 7 documents
Spectroscopic analysis of hot-water- and dilute-acid-extracted hardwood and softwood chips
2017
Hot-water and dilute sulfuric acid pretreatments were performed prior to chemical pulping for silver/white birch (Betula pendula/B. pubescens) and Scots pine (Pinus sylvestris) chips to determine if varying pretreatment conditions on the original wood material were detectable via attenuated total reflectance (ATR) infrared spectroscopy. Pretreatment conditions varied with respect to temperature (130 °C and 150 °C) and treatment time (from 30 min to 120 min). The effects of the pretreatments on the composition of wood chips were determined by ATR infrared spectroscopy. The spectral data were compared to those determined by common wood chemistry analyses to evaluate the suitability of ATR spe…
PURIFICATION OF HARDWOOD-DERIVED AUTOHYDROLYSATES
2012
Carbohydrate-containing hydrolysates (1.1 to 14.9% of wood dry matter) obtained from autohydrolysis (at 130 to 150°C for 30 to 120 minutes) of birch (Betula pendula) chips prior to pulping were purified with respect to non-carbohydrate materials, without carbohydrate losses, either by ethyl acetate extraction or XAD-4 resin treatment. In the former case, about 50% of lignin and practically all the furanoic compounds (2-furaldehyde and 5-(hydroxymethyl)furfural) could be removed, whereas in the latter case, the corresponding amounts were about 30% and 50 to 90%, respectively. A partial recovery of various unsaturated impurities is of importance, because they may act as inhibitors when bioche…
Multivariate Correlation between Analytical Data for Various Organics Dissolved during Autohydrolysis of Silver Birch (Betula pendula) Chips and Trea…
2014
Autohydrolysis pre-treatments were performed for the production of hemicellulose-rich autohydrolysates from silver birch (Betula pendula) chips prior to chemical pulping. Pre-treatment conditions were varied with respect to time (from 30 to 120 min) and temperature (130 and 150 °C), covering a P-factor range from 10 to 238. Hydrolysates were analyzed in terms of carbohydrates, lignin, volatile organic acids, and furanoic compounds. The analytical data were subjected to various chemometric techniques to establish the relationships between dissolved organic components, hardwood and softwood used in the experiments, and applied pre-treatment conditions. Using this method, differences between t…
Organic material dissolved during oxygen-alkali pulping of hot-water-extracted spruce sawdust
2016
Untreated and hot-water-extracted (HWE) Norway spruce (Picea abies) sawdust was cooked using the sulfur-free oxygen-alkali (OA) method under the following conditions: temperature, 170 °C; liquor-to-wood ratio, 5:1 L/kg; and NaOH charge, 19% on the oven-dry sawdust. In comparison with earlier studies conducted with birch sawdust, the spruce cooking yield data, together with the amount of the pulp rejects (78% to 86% for reference pulps from the initial feedstock and 73% to 83% for pulps from the HWE feedstock), revealed that the pretreatment stage prior to spruce OA pulping caused different effects on pulping performance. The analyses of the three main compound groups (i.e., lignin, volatile…
Multivariate Correlation between Analysis Data on Dissolved Organic Material from Scots Pine (Pinus sylvestris) Chips and their Autohydrolysis Pre-Tr…
2013
Various chemometric techniques were used to establish the relationship between the autohydrolysis conditions prior to pulping and the chemical compositions of the soluble organic materials removed from Scots pine (Pinus sylvestris) wood chips. The aqueous chip pre-treatments (autohydrolysis) were administered at 130 °C and 150 °C for 30, 60, 90, and 120 min, and the hydrolysates obtained were characterized in terms of total carbohydrates (various mono-, oligo-, and polysaccharides together with uronic acid side groups), volatile acids (acetic and formic acids), lignin, and furans (furfural and 5-(hydroxymethyl)furfural). Based on the analytical data gathered, a relatively accurate model for…
Autohydrolysis pretreatment of Arundo donax: a comparison between microwave-assisted batch and fast heating rate flow-through reaction systems
2015
Background: Autohydrolysis of lignocellulosic biomass in liquid hot water has been widely studied owing to its high efficiency and relatively low cost. In the perspective of industrial applications, continuous or semi-continuous processes are more interesting than batch systems. Moreover, microwave heating of pretreatment systems has been proposed to intensify the kinetics of the process. In this study, the autohydrolysis of Arundo donax was performed in pure liquid hot water using a microwave-heated batch reactor and a semi-continuous flow-through reaction system with fast heating rate at the same operating conditions with the aim of performing a systematic comparison between the two diffe…
Chemical Pretreatments of Wood Chips Prior to Alkaline Pulping - A Review of Pretreatment Alternatives, Chemical Aspects of the Resulting Liquors, an…
2015
The chemical industry is being forced to evaluate new strategies for more effective utilization of renewable feedstocks to diminish the use of fossil resources. In this literature review, the integration of both acidic and alkaline pretreatment phases of hardwood and softwood chips with chemical pulping is discussed. Depending on the pretreatment conditions, high-volume sulfur-free fractions with varying chemical compositions can be produced. In case of acidic pretreatments, the major products include carbohydrates (mono-, oligo-, and polysaccharides), whereas under alkaline (i.e., aqueous NaOH) pretreatment conditions, the sulfur-free fractions of aliphatic carboxylic acids, lignin, and ex…