Exploring interfacial properties and thermodynamic parameters of synthesized biodegradable surfactants from Brassica Juncea and their emulsification characteristics

Abstract

This study investigates the synthesis and characterization of four non-ionic surfactants of different spacer lengths derived from Brassica Juncea (mustard oil) and explore their potential applications. The chemical structures of the surfactants were confirmed by FTIR, 1HNMR spectroscopy and GC. Surface tension values of the surfactants were measured at various temperatures, unveiling temperature-dependent behaviour and associated thermodynamics. The critical micelle concentrations (CMC) of different surfactants were found to be very low (0.064–0.096 mmol/l at 303 K) compared to conventional surfactants. The CMC and the surface tension further decrease significantly with an increase in temperature. Surface-active thermodynamic parameters of the surfactants demonstrate their lower interfacial characteristics and enhanced self-aggregation capability. At CMC, the synthesized surfactants effectively decrease the interfacial tension (IFT) between water and dodecane to a notably low range of 9.5 to 12.1 mN/m, which is further reduced to a range of 3.2 to 6.1 mN/m at optimal salinity. The surfactants also show good emulsification properties, the emulsions formed in the water-dodecane system using the gemini surfactants as emulsifiers were extensively characterized, encompassing phase behaviour and droplet size distribution analysis. These emulsions exhibit favourable viscous properties, with viscosities ranging from 5 to 20 mPa.s at a 5 s-1 shear rate. This study establishes that the synthesized Gemini surfactants are viable candidates for Enhanced Oil Recovery (EOR), showcasing robust stability, interfacial activity, and favourable rheological properties, alongside biodegradability.