Grasas y Aceites, Vol 54, No 2 (2003)

Use of residual soapstock from the refining of edible vegetable oils to make biodiesel


https://doi.org/10.3989/gya.2003.v54.i2.255

J. Pereda Marín
Departamento de Ingeniería Química. Facultad de Química. Universidad de Sevilla, Spain

F. Barriga Mateos
Departamento de Ingeniería Química. Facultad de Química. Universidad de Sevilla, Spain

P. Álvarez Mateos
Departamento de Ingeniería Química. Facultad de Química. Universidad de Sevilla, Spain

Abstract


A procedure to obtain Biodiesel from “Oleinas” is studied. Biodiesel is a suitable product to replace diesel oil currently used to power the Diesel engines. It consists of a mixture of methyl esters of the fatty acids presents as triglycerides in vegetables oils (olive, sunflower, soya, rape oils). As a result of the refining of these oils for their use as food, a waste product is formed, the “oleinas” (acidulated soapstock). The oleinas consist of a mixture of triglycerides and free fatty acids, the latter amounting to 50% or more of the mixture and are subject to a fluctuating market, therefore it exist at times a problem for their disposal. In our research work we have tried to obtain biodiesel from oleinas. The process resulting from our experimental work is as follows:
1. Sterification of the free fatty acids with methanol, by acid catalysis, centrifuging the reaction product and removal of the acid-methanol phase. Drying of the latter. At this stage we have a product containing about 70% of methyl esters.
2. Transesterification of the triglycerides present in the sterified product with methanol by alkaline catalysis, washing the reaction product with a water methanol solution. Centrifuging and removal of the water-methanol phase. At this stage a biodiesel product is obtained containing about 90% of methyl esters.
3. Fractional vacuum distillation of the 90% biodiesel gives a final product with a methyl esters content higher than 98%.

Keywords


Acidulated soapstock; Biodiesel; Fatty acid methyl esters; Oleinas; Vegetable oils

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