Ammonium removal from aqueous solutions using sulfonated polystyrene grafted silica gel sorbent

A novel non-swelling sulfonated polystyrene grafted silica gel sorbent was synthesized for use in ammonium removal from aqueous solutions. The ammonium sorption equilibrium isotherm was determined at 298 K by batch experiments, and the effects of flow rate and initial solution pH on the sorption were measured by breakthrough experiments in a laboratory scale fixed bed column. The equilibrium data were fitted to the Langmuir, Freundlich, Langmuir-Freundlich, and Toth isotherm models. The breakthrough data were fitted to a dynamic isothermal mathematical model with an axial dispersion term to obtain the effective diffusion coefficient. The sorption rate of the sulfonated polystyrene grafted silica gel is higher than that of ion-exchange resins, which enables shorter cycle times in column processes for the grafted silica gel.