• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.589-593
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• 2007

재생 가능한 자원인 동식물성 기름을 원료로 제조되는 수송용 연료 바이오디젤은 낮은 대기오염물질 배출과 $CO_2$ Neutral 특성으로 환경친화적인 연료로 인정을 받으며 전세계적으로 그 생산량이 급격히 증가하고 있다. 대부분의 상용화 공정은 염기촉매를 이용한 전이에스테르화 반응에 근거하고 있으며 높은 생산성을 위해 연속 공정을 채택하고 있다. 원료유 중의 유리지방산(free fatty acid, FFA)은 염기 촉매와 반응하여 지방산염(Soap)과 수분을 생성하며 반응촉매의 투입양을 증가시카고 반응 후에 글리세롤과 지방산 메틸에스테르와의 분리를 어렵게 만든다. 높은 수율과 후속공정의 부하를 줄이기 위해서는 식물성 원료유 중의 FFA는 고체 산촉매 하에서 메탄올과 에스테르화 반응시켜 전환 제거되어야 한다. 본 연구에서는 고체산 촉매인 Amberlyst-15을 충전한 4단 PBR(Packed Bed Reactor, 충전율 60%(v/v))에서 반응시간과 반응온도에 따른 대두원유의 전처리 효율을 조사하였으며 최적 전처리 조건을 도출하였다. 최적 전처리 조건에서 대두원유는 초기 산가 1.6에서 0.4-0.6으로 연속 전처리할 수 있었다. 본 연구에서는 연속 흐름 반응기인 PFR(Plug Flow Reactor)와 4단 CSTR(Continuous Stirred Tank Reactor)에서 균질계 촉매인 KOH 존재하에 대두유와 메탄올과의 전이에스테르화 반응 특성을 조사하였으며 각 연속 반응시스템에서 최적 운전 조건을 도출하였다. PFR 반응기에서 반응온도, 반응시간, 반응물 흐름방향, static mixer(SM) 개수에 따른 반응특성을 조사한 결과, PFR에서의 최적 반응조건은 하향류 흐름 방향과 3개의 SM를 설치한 조건에서 반응시간 5.8분, 반응온도 90$^{\cdot}C$, 메탄올:오일 몰비 9:1, KOH 농도 0.8%로 도출되었다. CSTR 반응기에서는 반응온도와 체류시간에 따른 반응특성을 조사하였으며 최적반응 조건으로 반응온도 80$^{\cdot}C$, 메탄올/오일 몰비 9:1, KOH 농도 0.8%, 체류시간 18.4분, 교반속도 250rpm로 조사되었다.

• Clean Technology
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• v.30 no.1
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• pp.47-54
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• 2024

Jatropha oil extracted from the seeds of Nepalese Jatropha curcas, a non-edible crop, was used as a raw material and converted to biodiesel through a two-step process consisting of an esterification reaction and a transesterification reaction. Amberlyst-15 catalyst was applied to the esterification reaction between the free fatty acids contained in the Jatropha oil and methanol. The acid value of the Jatropha oil could be lowered from 11.0 to 0.26 mgKOH/g through esterification. Biodiesel was synthesized through a transesterification reaction between Jatropha oil with an acid value of 0.26 mgKOH/g and methanol over NaOH/γ-Al₂O₃ catalysts. As the loading amount of NaOH increased from 3 to 25 wt%, the specific surface area decreased from 129 to 28 m²/g and the pore volume decreased from 0.249 to 0.129 cm³/g. The amount and intensity of base sites over the NaOH/γ-Al₂O₃ catalysts increased simultaneously with the NaOH loading amount. It was confirmed that the optimal NaOH loading amount for the NaOH/γ-Al₂O₃ catalyst was 12 wt%. The optimal temperature for the transesterification reaction of Jatropha oil using the NaOH/γ-Al₂O₃ catalyst was selected to be 65 ℃. In the transesterification reaction of Jatropha oil using the NaOH/γ-Al₂O₃ catalyst, the reaction rate was affected by external diffusion limitation when the stirring speed was below 150 RPM, however the external diffusion limitation was negligible at higher stirring speeds.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.11
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• pp.1401-1407
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• 2008

1-Deoxynojirimycin (DNJ) is a strong $\alpha$-glucosidase inhibitor which inhibits hyperglycemia in animals. To select the Bacillus strains highly producing DNJ, 4,000 strains were isolated from soil and grain samples. By the inhibitory activity against $\alpha$-glucosidase, nine Bacillus strains were selected and then identified by 16S rDNA sequencing. B. subtilis S10 was finally selected as the best strain for the production of DNJ. Various carbon sources and nitrogen sources in culture medium were evaluated for the highest production of DNJ. As the results, the optimized concentration of carbon source and nitrogen source was 1.0% galactose and 1.6% polypeptone and the concentration of DNJ produced was 0.75 g/L. The effect of culture supernatant of B. subtilis S10 on lowering blood glucose level was investigated in streptozotocin (STZ)-induced diabetic mice model. Mice were randomly assigned to control group (saline) and three test groups such as acarbose group, silkworm powder group and B. subtilis S10 group. After eight-week oral feeding, blood glucose levels of the B. subtilis S10 and silkworm powder groups were respectively $209.1{\pm}19.6\;mg/dL$ (59.1%) and $208.6{\pm}39.8\;mg/dL$ (59.0%) lower than $510{\pm}10\;mg/dL$ of the control group. These results indicated that the culture supernatant of B. subtilis S10 was able to reduce the blood glucose level in STZ-induced diabetic mice.