HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kithome, M. Articles by Bomke, A. A. Search for Related Content PubMed Articles by Kithome, M. Articles by Bomke, A. A. GeoRef GeoRef Citation Agricola Articles by Kithome, M. Articles by Bomke, A. A.

Kinetics of Ammonium Adsorption and Desorption by the Natural Zeolite Clinoptilolite

Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, P.O. Box 1000, Agassiz, BC, Canada V0M 1A0

L. M. Lavkulich and A. A. Bomke

Dep. of Soil Science, Univ. of British Columbia, Vancouver, BC, Canada V6T 1Z4

*Corresponding author (PaulJ{at}em.agr.ca).

ABSTRACT

The kinetics of NH⁺₄ adsorption and desorption were investigated on the natural zeolite clinoptilolite to ascertain its ability to adsorb and release the important plant nutrient N in its NH⁺₄ form at various pH values and initial NH⁺₄ concentrations. Kinetics of NH⁺₄ adsorption were evaluated on the samples using solutions containing 140.1, 280.2, 560.4, and 840.6 mg L^–1 of NH⁺₄-N at pH 4, 5, 6, and 7, equilibrated for 5, 10, 15, 20, 30, 45, 60, 75, 90, and 120 min. Samples for NH⁺₄ desorption were equilibrated with 70.1, 280.2, 560.4, and 1401 mg L^–1 NH⁺₄-N solution at pH 4, 5, 6, and 7 for 2.5 h, and adsorbed NH⁺₄ extracted with 2 M KCl for 5, 10, 20, 30, 45, 60, 90, 120, 150, 180, and 300 min. Equilibrium time for NH⁺₄ adsorption ranged from 60 min for 140.1 mg L^–1 initial NH⁺₄-N concentration at pH 4 to 120 min for 840.6 mg L^–1 initial NH⁺₄-N concentration at pH 7. Desorption was nearly complete in 150 min for low initial NH⁺₄ concentrations and 200 min for high initial NH⁺₄ concentrations. Amounts of NH⁺₄ sorbed increased with increasing pH and initial NH⁺₄ concentrations. Models evaluated included the first-order kinetics, modified Freundlich, parabolic diffusion, Elovich, and heterogeneous diffusion. All the models adequately described the NH⁺₄ adsorption process, with r² values ranging from 0.955 to 0.999. With the exception of first-order kinetics, they also described the desorption process well, with r² values ranging from 0.897 to 0.999, for all pH and initial NH⁺₄ concentrations. Reaction rate coefficients (k) were calculated from the modified Freundlich model and ranged from 0.134 to 0.193 min^–1 for the adsorption process, and 0.129 to 0.226 min^–1 for the desorption process. The models indicated that NH⁺₄ adsorption and desorption by the zeolite was diffusion controlled. Data from this study indicated the potential use of the tested natural zeolite as an NH⁺₄ adsorbent and a controlled-release NH⁺₄ fertilizer.

Pacific Agri-Food Research Centre Contribution no. 562.

Received for publication February 4, 1997.

This article has been cited by other articles:

				T. M. DeSutter and G. M. Pierzynski Evaluation of Soils for Use as Liner Materials: A Soil Chemistry Approach J. Environ. Qual., April 20, 2005; 34(3): 951 - 962. [Abstract] [Full Text] [PDF]

				M. Quaghebeur, A. Rate, Z. Rengel, and C. Hinz Desorption Kinetics of Arsenate from Kaolinite as Influenced by pH J. Environ. Qual., March 1, 2005; 34(2): 479 - 486. [Abstract] [Full Text] [PDF]