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  • 學位論文

重金屬對於狼尾草生質物生產纖維酒精之影響

Effect of heavy metal ions in bioethanol production from Pennisetum purpureum

指導教授 : 柯淳涵
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摘要


本研究為利用狼尾草作為試材,本實驗分為三部分進行:(1)重金屬對於純糖發酵之影響、(2)重金屬對於狼尾草生質物之吸附及(3)含重金屬之生質物對於酵素水解的影響。第一部分是探討含重金屬之葡萄糖液,對其發酵之影響。反應條件為於37度水浴槽中,以轉速100�每分鐘去做72小時之搖瓶試驗。當添加微量重金屬時,有提高發酵產率的現象發生;一旦超過一定濃度則會明顯抑制發酵反應。第二部分生質物之前處理方法為將10公分長之試材浸泡於1.5 %硫酸中96小時,接著放入蒸氣槽後通入蒸氣,處理條件為180oC下持溫10分鐘。再將蒸爆漿進行重金屬吸附試驗,試材濃度為5克�100毫升,對不同含量之重金屬於37oC環境下進行水浴搖瓶48小時,最後利用火焰式原子吸收光譜儀測得吸附情況。由結果發現,當反應至36小時,吸附量會達到一平衡狀態,繼續搖瓶反應則不會有顯著的改變;第三部分為含有重金屬之漿料對於酵素水解影響之試驗,材料濃度為 5克�100毫升,並利用cellulase、β-glucosidase以及xylanase等酵素於37oC的環境下進行48小時水解反應,而酵素添加量比例為:4毫升酵素�100克絕乾重、12毫升酵素�100克絕乾重與24毫升酵素�100克絕乾重,最後利用HPLC測得葡萄糖含量。最後結果測得,在含重金屬鋅(Zn2+)濃度為836毫克�公升的情況下,其產率為145.92毫克�克絕乾重;而另一方面,在鉻(Cr6+)濃度為9.61毫克�公升的情況下有最高的產率864.04毫克�克絕乾重。由本試驗結果可得知,利用植生復育於重金屬污染土壤,其種植生質能源作物之可行性,亦可作為未來實際應用在污染地做試驗之參考依據。

並列摘要


Napier grass is one of the plants with high yield of full lignocellulose. This study used acid steam-exploded napier grass pulp to conduct assays. It was divided into three portion: (i) inhibition degree of glucose fermentation with heavy metal ions, (ii) adsorption of heavy metal ions on napier grass biomass and (iii) effect of heavy metal ions in enzyme hydrolysis process. First, in glucose fermentation, all heavy metal ions in trace amount was promoted bioethanol production, but when dosing overdosage of metal ions, the yield was decreased rapidly and inhibited ethanol production. Second, in part of adsorption, the equilibrium for adsorption of heavy metal ions was occurred after 36 h. After this equilibrium point, the amounts of adsorbed ions did not significantly change with time. Finally, for the saccharification of pretreated napier grass biomass, cellulase formulations were applied with three dosages: 4, 12, 24 percent to dried pulp (v/w). The flasks were water bathed at 37°C, shaken at 100 rpm for 48 h, and the samples were analyzed with HPLC. The optimal yield occurred in 24 mL/100 g DS and dosing the least concentration of Cr6+ (9.61 mg/L) for 864.04 mg/g. This study demonstrated the potential of phytoremediation in polluted places with heavy metal ions.

參考文獻


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