Modification of mineral surfaces by adsorption of biosurfactants produced by Streptomyces sp

Abstract This work has focused on adsorption of both biosurfactants and sodium dodecyl sulfate (SDS) anionic surfactant onto mineral surfaces activated by nickel(II) ions. Surfactants of biological origin produced by a new strain of Streptomyces sp. S4 isolated from the environment are analogues of surfactin. They adsorb on the magnesite, serpentinite and silica surface according to the Somasundaran-Fuerstenau isotherm model, changing the electrokinetic properties and hydrophobicity of these minerals. The culture broth was stable at pH 8. The critical micelle concentration for surfactin was 9.6 μM and for biosurfactants – 100 μM. The adsorption of anionic surfactants and biosurfactants decreased the measured value of the electrokinetic potential of the mineral particles. It was found that the adsorption of biosurfactants produced by Streptomyces sp. S4 may be a useful tool for mineral surface modifications that can be used for selective separation of minerals in flotation.