Synthesis, surface and thermodynamic parameters of some biodegradable nonionic surfactants derived from tannic acid

A series of nonionic surfactants derived from tannic acid were synthesized by reaction of tannic acid with different molar ratios of hydrolyzed caster oil. The chemical structures of the prepared surfactants were confirmed using FTIR and 1H NMR spectra. The molecular weights of the compounds were determined using viscosity measurements and Gel permeation chromatography (GPC). The surface properties of the synthesized surfactants including: surface tension, interfacial tension, critical micelle concentration (CMC), effectiveness (πcmc), efficiency (Pc20), maximum surface (Γmax) excess and minimum surface area (Amin) were determined. The emulsification power of the surfactants showed moderate emulsifying tendency towards organic substrate (light paraffin oil). The biodegradability of the prepared surfactants was tested in river water using Die-away method which confirmed that these compounds are readily biodegradable in the environment.