Process Enginering of Biodiesel Production from Residual Oil Contained in Spent Bleaching Earth by In Situ Esterification-Transesterification

Abstract

Biodiesel is an alternative diesel fuel that is produced from vegetable oils or animal fats. It consists of the mono alkyl esters formed by a catalyzed reaction of the triglycerides in the oil or fat with a simple monohydric alcohol. Biodiesel is a biodegradable, renewable, non-toxic and environmental friendly alternative fuel. It can be mixed with petroleum diesel in any proportion or used directly in diesel engines without modification. Spent Bleaching Earth (SBE) is an industrial solid waste of palm cooking oil industry that has a high residual oil and the potential to be utilized as biodiesel. This study aims to develop a biodiesel production process technology by utilizing the residual oil contained in SBE and to test the use of hexane in the transesterification process. Optimization was done by using the Response Surface Method.Variables studied included the catalyst concentration and reaction time. On the other hand, the deoiled SBE resulted from biodiesel production was tested as an adsorbent on biodiesel purification. The method used included an in situ acid catalyzed esterification followed by in situ base catalyzed transesterification. The results of the response surface analysis on transesterification showed that the optimum process was at NaOH concentration of 1.8% and reaction time of 104.73 minutes, with a predicted response rate of 97.18% and 95.63% for validation results. Furthermore, the effect the use of hexane can also increase the yield of biodiesel. It was obtained on the ratio hexane to methanol 0.4:1 (volume of hexane: volume of methanol). On the other hand, the reactivated bleaching earth and fresh bleaching earth were effective as an adsorbent in biodiesel production with still conform with the Indonesian National Standard (viscosity, density, acid number and saponification number)