Fatty acids methyl esters from soybean oil for biobased surfactants industry: Obtention C16 / C18 concentrate for use as feedstock

Abstract

Soybean fatty acid methyl esters (FAMEs) are used as biodiesel, a co-fuel according to current consumption figures. In addition, FAMEs are becoming increasingly important as biodegradable substitutes for mineral oils, such as oil for chainsaws, gearboxes, hydraulics, and lubricants for crude oil production. Therefore, the possibility of producing a wide spectrum of value-added products in oleochemical industry will guarantee the competitiveness of biodiesel plants in the market. In this way, soybean FAMEs of local production were modified to obtain the desired characteristics to produce biobased surfactants as methyl ester sulfonated (MES). In order to incorporate soybean FAMEs into the conventional MES manufacturing process, their lipid profile must be similar to that of the traditionally used raw material, that is, palm oil. This oil is composed of acids with a length between C12 and C18 and 44–50 % of unsaturated acids, a higher concentration of unsaturated acids is not convenient because generated impurities could affect the final color of the product. Thus, the objective of this work is to achieve a ratio between soybean C16/C18 FAMEs of 60/40, the maximum possible ratio from the initial C16/C18 of 11.0/87.6. In this study, molecular distillation and urea complexation were used as individual and combined techniques to obtain C16/C18 concentrate. In the molecular distillation a ratio of 16.2 / 83.1 was obtained with a yield of 23.2 % (evaporation temperature of 70 °C) while by urea complexation a ratio of 35.4/ 60.8 was obtained with a yield of 32.0 % (urea: FAMEs mass ratio of 1: 1). The most suitable combination of both techniques was a urea complexation stage followed by a molecular distillation stage. The obtained product had a ratio of 56.7 / 43.3 and a yield of 41.8 %. The results of this study could be applied to other vegetable sources to obtain an appropriate profile of FAMEs. Also, the developed process in this work could be used in the industry of green surfactants to produce the segmentation of biodiesel industry.