Evaluation of the Tensioactive Properties of Sodium Lignosulphonate Obtained from Spent Sulfite Liquor

Sodium lignosulphonate (NaLS) from spent sulfite liquor was purified by ultrafiltration, and the structure was confirmed by FTIR analysis. NaLS decreases water surface tension from 72.44 mN/m to 65.36 mN/m when its concentration increases from 0% to 1%. The critical aggregation concentration was determined using UV-Vis spectroscopy, and a value of 0.035% was obtained. NaLS (0.1%) was used as a cosurfactant in an oil-in-water emulsion prepared by a phase inversion method to encapsulate thyme essential oil. The formulation was stable for 24 h, with a droplet size of 154 nm and a polydispersity index value of 0.12.