Surface Activity and Thermodynamic Assessment of Surfactants Derived from Oreochromis Niloticus Oil (Nile Tilapia Fish)

Abstract

Surfactants were synthesized from Oreochromis niloticus (Nile Tilapia) oil via sulphonation and evaluated for surface-active and thermodynamic properties. The extracted oil had an acid value of 9.56 mg KOH/g, refractive index of 1.46, density of 1341 kg/m³, viscosity of 19.52 mPa.s, and lipid content of 18.20%. Fourier Transform Infrared Spectroscopy (FTIR) identified carboxylic acids and esters as major functional groups, while Gas Chromatography–Mass Spectrometry (GC-MS) detected oleic, palmitoleic, and decanoic acids among others. Three surfactants (NT-25, NT-30, NT-45) were obtained at sulphonation temperatures of 25°C, 30°C, and 45°C, respectively. They effectively reduced surface tension to 31.0, 36.0, and 44.0 mN/m, with critical micelle concentrations (CMC) of 2.86, 3.16, and 3.55 mmol/L, respectively. Wetting times ranged from 7.21 to 19.00 seconds, and foam stability reached 96% (NT-25), 95% (NT-30), and 96% (NT-45). NT-25 and NT-30 exhibited higher surface pressure at CMC (∏cmc), greater surface excess concentration (Γmax), and lower minimum surface area per molecule (A), enhancing their surface tension reduction compared to NT-45. These results suggest NT-25 and NT-30 possess excellent wetting and foam stability, making them promising for applications in soaps, detergents, and cosmetics.