Oil extraction from jatropha seeds using mixed surfactants aqueous-based solution for elimination of phorbol esters in the oil

Abstract

Due to the energy crisis and food demand, an exploration of non-edible oil bearing plants for biofuel and oleochemical production has been attended to protect the competition between food supply and biodiesel feedstock. The importance has been given on Jatropha curcas L. for fulfilling energy requirement. The innovation of Jatropha oil extraction using mixed surfactant aqueous-based solution could be the alternative extraction method for hexane extraction replacement because hexane is considered to be harmful to the environment and human health. However, the detoxification of phorbol esters in Jatropha oil, which considered to be the main toxic compound in term of tumor promoter and suspected to be carcinogen, is recommended prior to industrial utilization. The contamination of phorbol esters limit the application of methyl ester and glycerol from Jatropha-biodiesel production. Hence, this work proposed a new approach for Jatropha oil extraction using mixed surfactants aqueous-based solution. Theoretically, nonionic surfactant was selected to be mixed with extended anionic surfactant under the appropriate chemical proportion and physical conditions to obtain the highest oil yield. More importance, this method is expected to reduce phorbol esters in Jatropha oil. Experimental design includes the investigation of surfactant systems for the extraction, the optimum conditions, yield of oil extraction and the concentration of phorbol esters in the oil. The result shows that the optimal extraction system was 3% fatty alcohol C12-14 (2) ethoxylate nonionic surfactant, 0.02% Alfoterra 145-4PO and 0.6% sodium chloride which could yield the oil up to 73% for single extraction and could reach to 90% for double extraction. The appropriate extraction condition in this study were grain size 8-35 mesh, 1 min contact time with 130 rpm orbital shaking and 1 g of Jatropha kernel load per 10 mL of mixed surfactants aqueous-based solution or 1:10 solid to liquid ratio. Moreover, the phorbol esters concentration in the oil was reduced down to 1.84 mg/g which is significantly less than the oil obtained from hexane and compress extraction. Conclusively, this extraction method is considered to be clean technology concept and can be potentially useful for further development and application in the future.