Synthesis of eco-friendly fatty acid based zwitterionic biosurfactants from coconut oil sources and characterization of their interfacial properties

Synthetic routes of FEA surfactants where R1 corresponds to lauryl group in FEA-1, cetyl group in FEA-2 and stearyl group in FEA-3 respectively and R corresponds to cocoyl group [Display omitted] •Fatty acid based biosurfactants were prepared from coconut oil and the synthesis was confirmed by FT-IR, 1H-NMR and 13C-NMR analysis.•Static and dynamic surface tensions, interfacial tension, emulsification power, contact angle and foam stability were measured.•Environmental compatibility tests such as biodegradability, acute oral toxicity and acute dermal and eye irritation were performed.•Detergency test was performed in order to investigate the potential application in detergent products formulation. In this study, three different types of fatty acid based biosurfactants were prepared from coconut oil and the successful synthesis was confirmed by using FT-IR, 1H-NMR and 13C-NMR analysis. Interfacial characteristics assessment has shown that all of the prepared FEA surfactants are excellent in surfactant activity and effective in reducing interfacial free energy. In particular, FEA-3 is found to possess good soil removal capacity and emulsification activity since the molecules of FEA-3 surfactant are more closely packed at the interface and thus more efficient at lowering the interfacial energy. Environmental compatibility tests such as biodegradability, oral toxicity, and skin/eye irritation revealed that FEA-3 surfactant is easily biodegradable, mild, non-toxic and non-irritating, suggesting that FEA-3 surfactant can be employed in detergent products formulation.