Evaluation of ethanolamide based nonionic biosurfactant materials from chemically modified castor oil and used palm oil waste

Abstract

Successful preparation of the ethanolamide based nonionic biosurfactant materials from castor oil and used palm oil waste through a chemical modification process has been reported. Both oil wastes have been transesterified with methanol under the alkaline condition to yield 93.32 and 80.30% of methyl esters. The ricinoleic acid and 9,10,12-trihydroxystearic acid compounds are obtained in 93.44 and 94.86% yield; while the amidation of the methyl esters in a solvent-free reaction gives ricinoleyl ethanolamide in 49.81% yield, and biomaterials containing lauryl ethanolamide, myristyl ethanolamide, palmityl ethanolamide, and oleoyl ethanolamide derivatives yielded in 74.48%. The chemical structures of the products have been confirmed by FTIR, GC-MS, and ¹H-NMR spectrometers. Almost all biosurfactant materials gave higher HLB and lower surface tension compared with the Tween 80 as a positive control. Even though only ricinoleic acid and ethanolamide derivatives exhibit lower critical micelle concentration than the positive control, the ethanolamide derivatives from used palm oil give a stable foam volume up to 70 mL for 90 min and also give a stable emulsion between distilled water and gasoline to 5 days, which is remarkable. These findings show that the ethanolamide derivatives from castor oil and used palm oil waste are promising nonionic biosurfactant materials for industrial applications.