Hexane replacement for soybean extraction using microemulsion systems

Abstract

Hexane is commonly used as a solvent in vegetable oil extraction process. However, hexane has high volatility which results to the environmental problem from its process. So, the main objective of this study was to apply the microemulsion formation for soybean oil extraction. In order to investigate an alternative for vegetable oil extraction, this study proposed a technique by using surfactant-based aqueous extraction for replacing organic solvent extraction in conventional industrial process. This alternative can be categorized as one of Clean Technologies. The study aimed to introduce a surfactant system that was able to maximize soybean oil mobilization while minimize soybean oil solubilization. For this study, the result showed that the surfactant mixture of 3% Comperland KD and 0.1% Alfoterra 5PO and the surfactant mixture of 4% Span 80 and 0.1% Alfoterra 5PO were able to form microemulsion with soybean oil. These two systems were then selected for further study on soybean oil extraction. The results showed that only the system of mixed of 3% Comperland KD and 0.1% Alfoterra 5PO was able to extract and yield free soybean oil while the system of 4% Span 80 and 0.1% Alfoterra 5PO only yielded an aqueous emulsion phase. This may be because the solubilization that occurred in a microemulsion system. Therefore, a single surfactant; Comperland KD at different concentrations were carried out for soybean seeds extraction in comparison since it was expected that the single surfactant may reduce interfacial tension but not to enhance solubilization. However, the result of the single surfactant systems showed less efficiency for oil extraction as compared to the mixed surfactants system. Conclusively, from the condition used in this study, the mixed of 3%Comperland KD and 0.1% Alfoterra 5PO with 7.5% NaCl showed the maximum soybean oil extraction (85.77%) from soybean seeds at size 0.212 mm-0.425 mm. In addition, the contact time and soybean load were also varied and it was found that the extraction yielded the optimum efficiency for the extraction were at 30 min and1g load of soybean load per the surfactant solution 10 mL respectively.