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. (435 characters)