Optimization Of Various Pretreatments In The Enzymatic Hydrolysis Of Kapok, Oil Palm Empty Fruit Bunch And Kenaf Core Fibres For The Production Of Cellulosic Alcohol

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dc.contributor.authorTye, Ying Ying
dc.date.accessioned2017-11-10T01:08:59Z
dc.date.available2017-11-10T01:08:59Z
dc.date.issued2014-06
dc.description.abstractThe original kapok (Ceiba pentandra), oil palm (Elaeis guineensis) empty fruit bunch (EFB) and kenaf (Hibiscus cannabinus) core fibres were hardly to be hydrolyzed by enzyme without any pretreatments, which yielded only 0.8%, 2.6% and 0.4% of reducing sugar (glucose), respectively. Various pretreatments, namely water, acid and alkaline pretreatments prior to enzymatic hydrolysis of the three fibres for sugar production were optimized in this study. Response Surface Methodology (Expert Design®) was applied to statistically analyze and optimize pretreatments conditions based on total glucose yield as response variable. Moreover, the effects of chemical composition and physical structure of the fibre on the total glucose yield were discussed comprehensively. Based on the statistical analysis of RSM, the response surface models built for each pretreatment of all the three raw materials were polynomial equations. Besides, the optimum pretreatment condition for kapok fibre was the alkaline pretreatment with condition of 120 ºC for 60 min in 2.0% NaOH solution. While the optimum pretreatment conditions for EFB and kenaf core fibres were the same, which was the water pretreatment with condition of 170 ºC for 45 min. Among the fibres, alkaline pretreated kapok fibre achieved the highest total glucose yield (glucose yield calculated baed on the untreated fibre) (39.6%), followed by the water pretreated EFB fibre (38.1%) and kenaf core fibre (25.5%). Alkaline pretreated kapok fibre exhibited the highest total glucose yield, mainly due to its high tendency on lignin elimination and the most severe structural destructive effect. On the other hand, water pretreatment was the most effective method in enhancing the enzymatic hydrolysability of EFB and kenaf core fibres due to the removal of hemicellulose in a large amount (>77%). However, unlike EFB fibre, kenaf core fibre did not show better enzymatic hydrolysability after the pretreatment, which resulted in a low structural alteration and high lignin retained in the fibre. Moreover, it was believed that the increased of crystallinity index and decreased of crystallite size of all pretreated fibres might be parts of the reasons that improved the enzymatic hydrolysability of fibre. Fermentation of sugar hydrolyzate by yeast without supplement of nutrient had yielded 19.1%, 18.5% and 12.7% of total ethanol for kapok, EFB and kenaf core fibres, respectively. Based on the results obtained, it was found that fibres with different physical properties required different pretreatment process to have a better enzymatic hydrolysability. Moreover, the removal of the entire recalcitrant polymers (lignin and hemicellulose) from biomass by pretreatment was not necessary to maximize the conversion of cellulose into reducing sugar by enzymatic hydrolysis.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/5272
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectOptimization of various pretreatmentsen_US
dc.subjectin the enzymatic hydrolysisen_US
dc.titleOptimization Of Various Pretreatments In The Enzymatic Hydrolysis Of Kapok, Oil Palm Empty Fruit Bunch And Kenaf Core Fibres For The Production Of Cellulosic Alcoholen_US
dc.typeThesisen_US
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