ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Effect of Antioxidants and Additives on the Oxidation Stability of Jatropha Biodiesel)

ผู้เขียน:เดือนเพ็ญ ฉายทองดี, จรัญ ฉัตรมานพ, ดร.เพ็ญจิตร ศรีนพคุณ, ศาสตราจารย์

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Abstract

Jatropha biodiesel was produced by a transesterification reaction, using potassium hydroxide at 1.5% by weight of Jatropha oil as a catalyst. The mole ratio of methanol and Jatropha oil was 7:1. The temperature, speed of mixing and reaction time used were 45?C, 600 rpm and 1.5 h, respectively. Antioxidants and additives were added to Jatropha biodiesel. The range of antioxidant and additive concentrations was 0-750 and 0-1,000 ppm, respectively. The three antioxidants used were PG (3,4,5- trihydroxybenzoic acid propyl ester, propyl gallate), TBHQ (t-butyl hydroquinone) and BHA (butylated hydroxyanisole). The three commercial additives used were ZEP additive, NITROX and L-power. The induction time of biodiesel with either antioxidant or additive was measured according to EN14112, using a Rancimat instrument. The results showed that PG was the best antioxidant for the production of Jatropha biodiesel at concentrations of 50, 150, 250, 350, 500, 650 and 750 ppm, which improved the induction time from 4.21 with no additive to 18.93, 26.35, 30.20 32.98, 34.04, 36.01 and 37.55 h respectively. Regarding the effect on storage for 20 weeks, Jatropha biodiesel with PG added at a concentration of 150 ppm, resulted in an induction time from the first week storage of 26.35 h and this reduced to 23.59 h in the final week (10.47% reduction from the first week). The Jatropha biodiesel properties that resulted from the addition of PG at a concentration of 150 ppm were within the acceptable range, according to ASTM and EN Standards.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 044, Issue 2, Mar 10 - Apr 10, Page 243 - 250 |  PDF |  Page

ที่มา:วิทยาสารเกษตรศาสตร์ สาขา วิทยาศาสตร์

หัวเรื่อง:ไม่มีชื่อไทย (ชื่ออังกฤษ : Optimization of Medium Composition for L-phenylalanine Production from Glycerol using Response Surface Methodology)

ผู้เขียน:เมธี ขำดวง, จรัญ ฉัตรมานพ, Kanoktip Packdibamrung, ดร.เพ็ญจิตร ศรีนพคุณ, ศาสตราจารย์

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Abstract

L-phenylalanine was produced by genetically modified bacterium, Escherichia coli BL21(DE3), using glycerol as an alternative carbon source. Response surface methodology (RSM) involving central composite design (CCD) was adopted to evaluate the amount of L-phenylalanine produced. In this work, the optimum concentrations were determined of the major nutrients in the fermentation medium, which included glycerol, (NH4)2SO4, MgCl2, K2HPO4, KH2PO4, yeast extract and thiamine-HCl. Analysis using biomass weight (gL-1) and amino acid production (gL-1), indicated that the optimum medium composition and concentration for the biomass production were: glycerol 10 gL-1, (NH4)2SO4 10 gL-1, MgCl2 0.98 gL-1, K2HPO4 2.94 gL-1, KH2PO4 2.94 gL-1, yeast extract 0.878 gL-1 and thiamine-HCL 0.0878 gL-1, with a maximum biomass weight of 5.0 gDCWL-1. In addition, the optimum medium composition for L-phenylalanine production was: glycerol 10 gL-1, (NH4)2SO4 100 gL-1, MgCl2 0.64 gL-1, K2HPO4 1.91 gL-1, KH2PO4 1.91 gL-1, yeast extract 0.823 gL-1 and thiamine-HCl 0.0823 gL-1. The highest L-phenylalanine weight at the optimum nutrient concentration was 6.2 gL-1.

Article Info

Agriculture and Natural Resources -- formerly Kasetsart Journal (Natural Science), Volume 043, Issue 4, Oct 09 - Dec 09, Page 727 - 737 |  PDF |  Page