Ammonia removal from aqueous solution using natural Chinese clinoptilolite

This paper assesses the potential of natural Chinese clinoptilolite for ammonia removal from aqueous solution. In batch study, the effects of relevant parameters, such as contact time, pH and initial ammonia concentration were examined, respectively. The results show that although contact time needs at least 4 h in order to attain exchange equilibrium, ammonia removal by clinoptilolite occurs rapidly within the first 15 min of contact time; the pH has an effect on ammonia removal efficiency as it can influence both the character of the exchanging ions and the clinoptilolite itself; the ammonia removal capacity of clinoptilolite increases with the increase of initial ammonia concentration. In column study, clinoptilolite bed was exhausted at different flow velocities and ammonia breakthrough capacity of clinoptilolite bed was calculated. Furthermore, the optimum regeneration conditions were considered. The results show that flow velocity can affect breakthrough capacity of clinoptilolite by changing hydraulic retention time and the volume of 15-20 BV of 0.5 mol/L sodium chloride solution at pH 11-12 is sufficient for complete regeneration of clinoptilolite in column. (C) 2005 Elsevier B.V. All rights reserved.