ferro-precipitate, adsorption, SDS, zeta potential

The main aim of the paper is to evaluate ferro-precipitates as immobilization agents for removing selected surfactants from aqueous solutions. Two ferro-precipitates based on iron oxides were used. Adsorbents were varied both in elementary composition and mineral composition. Sodium dodecyl sulphate (SDS) was used as a model anionic surfactant. Simultaneous measurements of the surfactant?s adsorption and zeta potential determination of the (adsorption) suspensions were carried out. The adsorption isotherms were found to be of typical Langmuir type; values of the SDS adsorption capacities were calculated (0.21 mmol/g for SDS on sample 1 and 0.44 mmol/g for SDS on sample 2, respectively). The shape of the adsorption isotherms was correlated with zeta potential values at the adsorption equilibrium. The addition of SDS affects the value of ?- potential, making the zeta potential values more negative.