Extraction of starch, xylose and glucose from oil palm trunk for bioethanol production
Use of oil palm trunk as sugars resource of biomass is currently under intensive study as an alternative growth substrate for bio-based chemical an energy production. It will benefit the environmental and reduce the agricultural waste. The complexity of chemical compositions in lignocelluloses...
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/99435/1/FPAS%202021%2013%20UPMIR.pdf |
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| Summary: | Use of oil palm trunk as sugars resource of biomass is currently under intensive
study as an alternative growth substrate for bio-based chemical an energy
production. It will benefit the environmental and reduce the agricultural waste.
The complexity of chemical compositions in lignocelluloses as inhibits in
degradation of lignin, hemicelluloses and cellulose which contain starch, five-and six-carbon sugars; prior to hydrolyzed and followed by co-fermentation for
bioethanol production. Generally, this study aims to optimize the extraction of
starch and mixed xylose-glucose from oil palm trunk and co-fermentation
process of mixed sugars to bioethanol.
Chemical analysis was carried out based on TAPPI Test Methods (TAPPI, 2000)
in determination of the chemical compositions of different levels and different
portions of OPT. Low lignin and hemicelluloses and cellulose were found in this
batch of study. It shows that OPT contains considerable extractives content
which is valuable be source of chemical value added products like fermentable
sugars.
For the study 2 (Starch extraction by Distilled Water and Chemical from OPT),
starch in the oil palm trunk was extracted by 0.2 % sodium metabsisulphite (w/v)
and 0.5 % lactic acid (v/v), and aqueous water respectively treated with levels of
temperatures and times. Value P≤0.01 significance was observed for the main
effects (temperature and time) on the starch yield with water solution and
chemicals. A significant interaction was also found between two main effects
(temperature and time). 19.7 % of starch yield was obtained by distilled water at
50 °C, 1 h, whereas 14.0 % of starch was obtained by chemicals at 26 ± 2 °C, 1
h). From the Response Surface Methodology (RSM) optimization analysis,
optimum starch yield 12.8 % was extracted by room temperature 26 ± 2 °C and
1 h by chemical solution. Whereas, from the RSM optimization analysis, optimum starch yield 16.3 % was extracted by distilled water under parameter 50 °C and
1 h. From the findings for study 2, the optimum starch yield can be obtained in
lower temperature when OPT powder treated with chemicals solution than
aqueous water.
Continuous dilute acid hydrolysis and simultaneous acid hydrolysis (115 °C, 120
°C and 130 °C reacted with 15 min, 30 min and 60 min) for producing xylose and
glucose. 2 %, 4 % and 6 % of acid sulphuric was used for hydrolysis process.
For continuous acid hydrolysis, optimum parameter of starch extraction method
parameter (0.2 % sodium metabsisulphite (w/v) and 0.5 % lactic acid (v/v), 26 ±
2 ˚C and 1 h), the extracted starch was mixed with residue of oil palm trunk
powder for dilute acid hydrolysis process. Simultaneous acid hydrolysis used
untreated raw OPT powder for glucose and xylose production. The higher
glucose yield occurred at dilute acid hydrolysis with the parameter of 6 %
sulphuric acid concentration reacted for 60 min on 60 mesh of OPT powders at
100 °C with a total glucose yield of approximately 15.3 % by simultaneous
hydrolysis. The optimum xylose yield occurred with the parameter of 2 %
sulphuric acid concentration reacted for 30 min on 60 mesh of OPT powders at
115 °C with a total xylose yield of approximately 32.4 % by continuous acid
hydrolysis. Value P≤0.01 significance was observed for the main effects (acid
concentration, temperature and time). By RSM analysis, optimum glucose and
xylose can be obtained by conducting continuous hydrolysis temperature 130 °C
for 53 min with 2 % acid concentration. Conclusively, the total yield of glucose-xylose was improved and approximately range of 2.5 % - 28.8 % higher than
total glucose-xylose yield from untreated OPT powder.
Co-fermentation of glucose and xylose to bioethanol was carried out using
engineered strains of Saccharomyces cerevisiae 424A(LNH‐ST) and E.coli
strain B, respectively. There was a preferential order of sugar utilization: first
using glucose followed by xylose. Generally, the optimum ethanol yield of 85.41
% using yeast as fermentation microbes was obtained at temperature 30 °C, pH
4. While, the optimum ethanol yield obtained from E.coli strain B was 86.01 % at
temperature 34 °C, pH 6. Value P≤0.0001 significance was observed for the
main effects (pH and temperature). From the optimization analysis, 87.9 % of
ethanol conversion yield can be obtained by conducting the fermentation at
temperature 34 °C and pH 6 by E.coli strain B; whereas 82.1 % of ethanol
conversion yield can be obtained at 30 °C and pH 4 by S.cerevisiae 424A(LNH-ST).
Generally, Oil palm trunk contains considerable amount of extractives and lower
lignin which suitable for starch and sugars extraction especially glucose and
xylose and potentially be one of the biomass resource energy in bioethanol production. |
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