Investigation on natural and pretreated Bulgarian clinoptilolite for ammonium ions removal from aqueous solutions.

The possibilities for ammonium ions removal from aqueous solutions by natural and NaCl pretreated Bulgarian clinoptilolite from Beli plast deposit were studied. Experiments were carried out using batch method. The adsorption of NH4(+) was investigated as a function of the solution pH, dosage of adsorbent, initial ammonium concentration and temperature. The results clearly showed that the treatment with NaCl improved both the adsorption capacity and the removal efficiency of natural clinoptilolite. The equilibrium experimental data for adsorbed NH4(+) ions on clinoptilolite samples were correlated better by the Langmuir isotherm model. The maximum adsorption capacities for ammonium ions shown by natural and pretreated clinoptilolites (CL_Na and CL_Na(t)) were 7.85, 12.29 and 18.40 mg/g, respectively. The results indicated a significant potential of the natural and conditioned clinoptilolites as adsorbents for ammonium removal.