Subcritical hydrolysis followed by methyl estrification was used to produce bio-diesel from low valued waste cooking oil at mild reaction conditions in this study. More than 90% fatty acid methyl esther (FAME) conversion was achieved by subcritical hydrolysis without using catalysts at 275℃ for 45 minutes. The highest conversion to linoleic acid (C18:2) was obtained at this condition. The higher content of free fatty acid (FFA) in waste cooking oil resulted in higher conversion to FAME. It was also observed more prominent at high temperature due to auto catalytic behavior of FFA. FAME yield found about 92% without using catalyst; whereas 98% yield was obtained using 80% TiO2 loading S-TiO2/MCM-41 catalyst at 220℃ and 20 minutes. The amount of FAME increased may be due to trans-esterification of un-reacted TG, DG, and MG with methanol remained during the hydrolysis stage. The higher FAME conversion means the better quality bio-diesel.

• Md Sufi Ullah Siddik Bhuyan(Department of Environmental Engineering, Sangji University)
• Eun Hei Lee(Department of Environmental Engineering, Sangji University)
• Abul Hasnat MD Ashraful Alam(Department of Environmental Engineering, Sangji University)
• Soa Choi(Department of Environmental Engineering, Sangji University)
• Ruri Lee(Department of Environmental Engineering, Sangji University)
• Kwanghyeon Song(Department of Environmental Engineering, Sangji University)
• Yong Chan Seo(Department of Environmental Engineering, Sangji University)