Study on Quick Adsorption Characteristics of Ammonia on Natural Clinoptilolite

The characteristics of ammonia nitrogen adsorption on the clinoptilolite was studied by static shaking table experiment, and the effect of clinoptilolite dosage and metal cations on quick adsorption of ammonium on the clinoptilolite investigated. The results indicated that the adsorption of ammonia nitrogen on clinoptilolite was fitted well with the Langmuir isotherm, and the maximum adsorption capacity was 12.903 mg/g. The removal rate increased with the decrease of the clinoptilolite size, and the adsorption process followed the pseudo-second-order kinetics model. Ammonium cations were exchanged with Na⁺ primarily, and then Ca²⁺. With the increase of ammonia nitrogen concentration and the extension of absorption time, the ratio of Na⁺ to removed NH₄⁺ decreased, and vice versa of Ca²⁺ to removed NH₄⁺.Clinoptilolite dosage was proportional to the ammonia nitrogen removal rate and the total metal cations released to water. With increasing dosage of the clinoptilolite, the ratio of Na⁺ to removed NH₄⁺ increased from 1.222 to 1.383. The inhibitory effect of clinoptilolite adsorption of ammonia nitrogen was in the order of K⁺>Ca²⁺>Na⁺>Mg²⁺, when the adsorption solution was added with four cations respectively.