Kinetics And Optimization Studies Of Pressed Pericarp Fibers Pretreated With Organosolvent
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Date
2012-07
Authors
Hii, Kiew Ling
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The existence of lignin in pressed pericarp fibres (PPF) could inhibit the
cellulolytic microorganisms from reacting with cellulose which directly inhibits the
cellulolytic enzyme activities. In order to increase the susceptibility of cellulose, PPF
was treated with organic solvent under high pressure and temperature in a high
pressurized reactor (HPR). Monohydric alcohols (propanol) showed better
delignification and hydrolysis at 38.5% and 46.1%, respectively. Ethanol was chosen
as pretreatment solvent for further screening of catalyst due to its wide availability
and economical perspective. Results showed that ethanol catalysed by nitric acid
gave the highest delignification (48.9%) and hydrolysis (96%) of PPF, an increase of
7.4-times from the untreated PPF (raw PPF). In this study, optimization of conditions
for PPF pre-treatment was also carried out using one-factor-at-a-time method (OFAT)
and a statistical tool. It was found that an optimal PPF pretreatment was achieved at
180oC, ethanol to water ratio of 0.65 aided with 0.8% (w/w) of nitric acid. For the
response surface methodology (RSM) via central composite design (CCD), it was
found that ethanol to water ratio 0.61 catalysed by 0.69 % (w/w) nitric acid at 183 oC
with reaction time of 92 min was the best condition for delignification (55.2 %) and
hydrolysis of PPF (90 %) as compared to the untreated condition. The irreversible
simultaneous reaction rate model involving 3 species of lignin was proposed and
modified, and found that it fitted well with the experimental data at co-efficient of
determination (R2) 0.91. As for the cellulose retained and PPF hydrolysis, a
conventional reaction rate model with slight modification and a basic enzymatic
reaction mechanism were proposed, respectively.
Description
Keywords
Kinetics and optimization studies of pressed pericarp fibers , pretreated with organosolvent