2.10. Liquid lipase SL-4 catalyzed biodiesel production
Transesterification reactions by liquid lipase SL-4 were conducted in 50 mL shaking flasks and incubated at 50◦C in ather most at shaking bed with a stirring rate of 200 rpm for 36 h.The reaction mixtures consisted of 0.55 g soybean oil, short-chainalcohol (methanol or ethanol, 3:1 molar ratio between alcohol andoil) by added in a step, 15% water content (w/w, based on the oil weight, g) and 0.4% enzyme (w/w, based on the oil weight, g). After these reactions, the optimum short-chain alcohol (methanol) was selected for the follow-up tests. The influence of crucial operational parameters such as molar ratio of alcohol/oil from 1:1 to 5:1, the methanol addition approach in three steps at intervals of 6 h, 8 h,10 h and 12 h, enzyme amount from 0.1% to 0.7% (w/w, based onthe oil weight, g), water content from 2% up to 35% (w/w, based on the oil weight, g), reaction temperature from 30◦C to 60◦C and reaction time up to 72 h on the biodiesel yield, was systematically studied. Except for the corresponding volume of Tris–HCl (pH 8.5)buffer instead of the free lipase, transesterification reactions in thesolvent-free system under the same conditions were employed as the controls. After a certain reaction period, 50 L samples weretaken from the reaction mixture and centrifuged to obtain theupper layer. Then, 10 L with drawn from the supernatant and 290 L of 1 mM heptadecanoic acid methyl ester, severed as theinternal standard, were precisely measured and mixed thoroughlyfor gas chromatography (GC) analysis for biodiesel yield according to the method reported in our previous work [10,17].
2.10 เอนไซม์ไลเปสของเหลว SL 4 catalyzed ผลิตไบโอดีเซลTransesterification reactions by liquid lipase SL-4 were conducted in 50 mL shaking flasks and incubated at 50◦C in ather most at shaking bed with a stirring rate of 200 rpm for 36 h.The reaction mixtures consisted of 0.55 g soybean oil, short-chainalcohol (methanol or ethanol, 3:1 molar ratio between alcohol andoil) by added in a step, 15% water content (w/w, based on the oil weight, g) and 0.4% enzyme (w/w, based on the oil weight, g). After these reactions, the optimum short-chain alcohol (methanol) was selected for the follow-up tests. The influence of crucial operational parameters such as molar ratio of alcohol/oil from 1:1 to 5:1, the methanol addition approach in three steps at intervals of 6 h, 8 h,10 h and 12 h, enzyme amount from 0.1% to 0.7% (w/w, based onthe oil weight, g), water content from 2% up to 35% (w/w, based on the oil weight, g), reaction temperature from 30◦C to 60◦C and reaction time up to 72 h on the biodiesel yield, was systematically studied. Except for the corresponding volume of Tris–HCl (pH 8.5)buffer instead of the free lipase, transesterification reactions in thesolvent-free system under the same conditions were employed as the controls. After a certain reaction period, 50 L samples weretaken from the reaction mixture and centrifuged to obtain theupper layer. Then, 10 L with drawn from the supernatant and 290 L of 1 mM heptadecanoic acid methyl ester, severed as theinternal standard, were precisely measured and mixed thoroughlyfor gas chromatography (GC) analysis for biodiesel yield according to the method reported in our previous work [10,17].
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