SURFACE-ACTIVITY OF BAGASSE LIGNIN DERIVATIVES FOUND IN THE SPENT LIQUOR OF SODA PULPING PLANTS

Lignin compounds present in the black liquors from alkaline pulping of bagasse are separated by evaporation to dryness or precipitation by a cidifying to pH 2. The separated lignin compounds exhibit the surface active characteristics of weak acid surfactant mixtures. Their surface tension versus concentration semi-log plot indicates a pattern simila r to the break found at the critical micelle concentration of conventi onal surfactants. The surface activity of the lignin derivatives is st rongly pH sensitive, and essentially vanishes under acidic pH conditio ns.