Since biodiesel as bioenergy is defined as ester compounds formed by esterification of animal/vegetable oils, in this study three vegetable cooking oils (market, waste and refined waste ones) were esterified by reactions of alkali catalyst and immobilized enzyme. The fatty acid composition of the formed ester compounds was analyzed to investigate the feasibility of biodiesel production.
By lipolysis (i.e, hydrolysis of Triglyceride (TG)), all three vegetable oils used in this study were found to produce Diglyceride (DG), Monoglyceride (MD) and Fatty acid ethylester (FAEE). However, the amount of produced FAEE (which can be used as an energy source) was in the increasing order of market cooking oil, waste one and refined waste one. With NaOH catalyst, FAEE was produced about 24.92, 17.63 and 11.31 % for the respective oils while adding Lipozyme TL produced FAEE about 43.54, 38.16 and 24.47 %, respectively. This indicates that enzyme catalyst is more effective than alkali one for transesterification. In addition, it was found that the composition of fatty acids produced by hydrolysis of TG was unchanged with alkali and immobilized enzyme reactions. Thus it can be expected that stable conditions remain in the course of mixing with gasoline whose composition is similar to that of the fatty acids.

Abstract
 1. 서 론
 2. 재료 및 방법
  2.1. 사용 재료
  2.2. 점도 측정
  2.3. 비누화가 측정
  2.4. 요오드가 측정
  2.5. 산가 측정
  2.6. 과산화물가 측정
  2.7. 에탄올화 반응
  2.8. 에탄올화 반응의 분석 방법
 3. 결과 및 고찰
  3.1. 기초 물성
  3.2. HPLC에 의한 구조분석
  3.3. GC-FID 에 의한 지방산 조성 분석
 4. 결 론
 참 고 문 헌

• 신춘환(동서대학교 에너지환경공학과) | Choon-Hwan Shin (Department of Energy & Environmental Engineering, Dongseo University) Corresponding Author