Abstract
This work addresses a novel microwave-assisted, acid-catalysed, organosolv (EtOH/H2O) system for the selective fractionation of bamboo, examining the effects of the temperature (110–190 °C), solvent system (EtOH/H2O) and catalyst amount (0–5 vol.% formic acid) on the process. The statistical analysis of the results revealed that the operating variables have a significant influence on bamboo fractionation, allowing the selective production of (i) a cellulose-rich solid fraction, (ii) a hemicellulose rich water-soluble fraction and (iii) a lignin rich solid fraction. The yields of each of these fractions varied between 51 and 94%, 2 and 23% and 2 and 32%, respectively. Increasing temperature exerted a positive effect on bamboo decomposition, increasing the overall bamboo conversion and influencing the effect that the solvent system (EtOH/H2O) has on the process. At low tem- perature (110 °C) the solvent system does not have much influence, while a synergetic interaction between EtOH and H2O took place at higher temperatures, which allowed better results to be obtained with EtOH/H2O mix- tures than with the pure solvents alone. The effect of the catalyst was relatively weak, being greatest when using a high temperature (190 °C) and high proportions of water (> 85 vol.%) in the solvent system. With respect to the properties of each fraction, the cellulose rich solid fraction was made up of un-reacted cellulose (44–83 wt. %), hemicellulose (0–21 wt.%) and lignin (12–34 wt.%); the water-soluble hemicellulose rich fraction consisted of a mixture of oligomers, sugars, carboxylic acids, ketones and furans; and the solid rich lignin fraction com- prised high purity (> 95 wt.%) organosolv lignin. The optimisation of the process revealed that by using a temperature of 190 °C, a solvent system consisting of 45 vol.% EtOH and 55 vol.% H2O with a concentration of formic acid of 5 vol.% it is possible to fractionate bamboo into a high purity (84 wt.%) cellulose solid fraction, very pure (> 95%) organosolv lignin and a rich water-soluble hemicellulose fraction consisting of a mixture of oligomers (27 wt.%), sugars (56 wt.%) and carboxylic acids (14 wt.%); thus converting this process into a very promising method for the selective fractionation of bamboo.
Original language | English |
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Article number | http://dx.doi.org/10.1016/j.enconman.2017.10.077 |
Pages (from-to) | 147-160 |
Number of pages | 14 |
Journal | Energy Conversion and Management |
Volume | 155 |
Issue number | 1 |
Early online date | 13 Nov 2017 |
DOIs | |
Publication status | Published - 1 Jan 2018 |
Bibliographical note
Crown Copyright © 2017 Published by Elsevier Ltd. All rights reserved.This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy.Keywords
- Bamboo
- Biomass fractionation
- Microwaves
- Organosolv
- Value-added products