Application of a compound containing silica for removing ammonium in aqueous media



In the present investigation, removal of ammonium from aqueous solutions by a compound containing silica was considered. The compound was a waste of ferrosilicon compound produced during Ferro-alloy manufacturing. The results showed that an increase in the pH of solution up to 7 caused a rapid increase in the adsorbed ammonium to 36.21 mg/g. But adsorbed ammonium was decreased to 26.51 mg/g as the initial pH reached to 10. The amount of adsorbed ammonium was increased with contact time and initial ammonium concentration. A contact time of 180 min was selected because there was no significant increment in adsorbed ammonium as contact time was further increased. The results exhibited suitability of the pseudo-second order kinetic model (R2 = 0.9867). Increasing initial ammonium concentration from 10 to 180 mg/L resulted in an increment in adsorbed ammonium from 6.69 to 59.13 mg/g, respectively. The obtained data were fitted to Langmuir, Freundlich, and Dubinin–Radushkevich (D-R) isotherm models in which the obtained correlation coefficient showed the relatively better fitness of the data to Langmuir model (R2 = 0.9969) with a maximum adsorption capacity of 78.74 mg/g. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 105–111, 2015