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 Google Scholar Google Scholar Articles by Kim, Y. K. Articles by Hatfield, J. D. Search for Related Content PubMed Articles by Kim, Y. K. Articles by Hatfield, J. D. Agricola Articles by Kim, Y. K. Articles by Hatfield, J. D.

Fixation Kinetics in Potassium-Aluminum-Orthophosphate Systems¹

ABSTRACT

The rate of removal of phosphate and potassium from solution was studied by contacting an aluminum-impregnated, cation exchange resin with solutions of monopotassium phosphate in concentrations of 0.05 to 0.25M and with atomic ratios Al:P from 0.25 to 4.0. The removal of both K and P from solution followed first-order reaction models for all experimental conditions, the K being removed faster than the P. The rate constants for K and P removal increased as the ratio Al:P increased, but were affected to a lesser extent by the initial concentration of KH₂PO₄. The concentration of Al with time agreed with a consecutive first-order reaction model involving cation exchange and precipitation. The rate constants for each experimental condition were evaluated by nonlinear regression analysis, and the reaction model represents the data well. The precipitate (prepared in 0.25 or 1M KH₂PO₄ solution) was identified as potassium aluminum taranakite by chemical and x-ray analysis. The phosphate retained in the resin was negligibly small and perhaps was occluded in the beads. Phosphate was removed from solution by the precipitation of taranakite. The taranakite precipitation rate constant, k₄, varied directly with the atomic ratio Al:P and inversely with the initial KH₂PO₄ concentration, C_o, by the correlation k₄ = 1.09 (Al:P)^1.066 (C_o)^-0.401.

¹ Contribution from the Division of Chemical Development, National Fertilizer Development Center, Tennessee Valley Authority, Muscle Shoals, AL 35660.

² Research Chemist.

³ Retired Research Chemists.

Received for publication June 25, 1982. Accepted for publication December 15, 1982.