A study of metal ion adsorption at low suspended-solid concentrations

A procedure for conducting adsorption studies at low suspended solid concentrations in natural waters (<50 mg l⁻¹) is described. Methodological complications previously associated with such experiments have been overcome. Adsorption of zinc ion onto synthetic colloidal titania (TiO₂) was studied as a function of pH, supporting electrolyte (NaCl) concentration (0·1-0·002 m) and particle concentration (2–50 mg l⁻¹). The lack of success of the Davis Leckie site bonding model in describing Zn(II) adsorption emphasizes the need for further studies of adsorption at low suspended-solid concentrations.