Synthesis and Interfacial Properties of Bio-Based Zwitterionic Surfactants Derived from Different Fatty Acids in Non-Edible Vegetable Oils

Waste cooking oils and non-edible vegetable oils are abundant and renewable resources for bio-based materials which have showed great potential applications in many industries. In this study, five fatty acids commonly found in non-edible vegetable oils, including palmitic acid, stearic acid, linoleic acid, linolenic acid, ricinoleic acid, and their mixtures, were used to produce bio-based zwitterionic surfactants through a facile and high-yield chemical modification. These surfactants demonstrated excellent surface/interfacial properties with the minimum surface tensions ranging from 28.4 mN/m to 32.8 mN/m in aqueous solutions. The interfacial tensions between crude oil and surfactant solutions were remarkably reduced to lower values ranging from 0.0028 mN/m to 0.1983 mN/m without the aid of extra alkali, which particularly implied a great potential application in enhanced oil recovery. Meanwhile, these bio-based surfactants also showed good wetting properties (contact angles of similar to 51 degrees comparing with that of double distilled water, 92.04 degrees) and appropriate predicted biodegradability (degradation order of weeks for bio-based surfactants synthesized from saturated fatty acids, and months for those synthesized from unsaturated fatty acids). Bio-based surfactants synthesized from unsaturated fatty acids showed better interfacial properties in reducing interfacial tension between crude oil and formation water. The bio-based surfactants presented in this study are alternative substitutes for traditional petroleum-based surfactants in various surfactant application fields.