Biopolymers for dye removal via foam separation

Two commercially available biopolymers are investigated as an alternative to classical surfactants in dye removal via foam flotation. Cationic dyes can be removed with efficiencies above 96% and enrichment factors in the foam of about 6. In comparison to the anionic surfactant sodium dodecyl sulfate (SDS), dye removal is slightly lower, but less water is needed to stabilize the foam. The removal efficiency of anionic dyes, e.g. methylene orange, with the pure biopolymer is low (about 5%) but increases significantly (up to 70%) in the presence of a cationic collector, e.g. dodecyltrimethylammonium bromide (DTAB). These results show that we can replace the classical surfactant by a more environmentally friendly alternative.