| Abstract: |
When little organic carbon is present in a sediment or aquifer, sorption of organic solutes must be controlled by mineral surfaces. Adsorption of these solutes depends on pH, electrolyte concentration, and adsorption of unrelated inorganic ions. Interactions among adsorbing species can significantly enhance or inhibit adsorption. The adsorption of anionic and cationic surfactants on quartz and corundum in the presence of a background electrolyte, and the coadsorption of an anionic surfactant enhanced by Ca++ have been simulated successfully using HYDRAQL, a chemical speciauon program including a triple-layer adsorption model. Surface ionization constants, electrolyte binding constants, and surfactant binding constants were determined from five independent experimental investigations. Surfactants are assumed to adsorb as single ions at low solution concentration and as clusters resulting from hydrophobic interactions between molecules at high concentration. The simulation accounts for experimental adsorption densities, zeta potentials, and for Ca++ coadsorption, froth flotation recovery. |
