Biodiesel production from oilseed plants using ferric sulfate and sodium hydroxide

Abstract

To study possibility of 30 oilseed plant species in Thailand to use as raw materials to produce biodiesel. The amount of oil, free fatty acid (FFA), saponification number (SN) and iodine value (IV) of these oilseed plants were in the range of 13-69%, 0.64-30.13%, 161.23-209.54 mgKOH/g and 45.13-164.38 mgI2/g, respectively. Biodiesel from these oilseed plant species could be synthesized by both transesterification reaction and esterification reaction. Transesterification reaction was carried out by using 12:1 molar ratio of methanol to oil and 1%wt of NaOH at 65?C for 1.5 h for oils having FFA content less than 3%. Esterification reaction was carried out by using 10:1 molar ratio of methanol to oil and Fe2(SO4)3 at 65?C for oils having FFA content more than 3%. For the reaction time and amount of catalyst of esterification reaction, 3% wt of Fe2(SO4)3 for 1 h, 3% wt of Fe2(SO4)3 for 2 h and 5% wt of Fe2(SO4)3 for 3 h were used for oils having FFA 10%, 20% and 30%, respectively. All of these oilseed plant species gave biodiesel having flash point more than 120?C and viscosity, density, acid value and ester content in the range of 3.2-5.5 cSt, 866.95-887.64 g/cm3, 0.1252-0.4404 mgKOH/g and 91.71-96.83%, respectively. According to the %oil content, saponification number, iodine value, viscosity, density, flash point, acid value and ester content, the biodiesel from 15 oilseed plant species could be potentially used and they met the major specification of biodiesel standards.