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This article in SSSAJ

  1. Vol. 59 No. 1, p. 248-255
     
    Received: Aug 23, 1993


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doi:10.2136/sssaj1995.03615995005900010039x

Modeling Transport Kinetics in Clinoptilolite-Phosphate Rock Systems

  1. E. R. Allen ,
  2. L. R. Hossner,
  3. D. W. Ming and
  4. D. L. Henninger
  1. Dep. of Agronomy, Oklahoma State University, Stillwater, OK 74078
    Dep. of Soil and Crop Sciences, Texas A&M University, College Station, TX 77840
    NASA Johnson Space Center, Houston, TX 77058

Abstract

Abstract

Nutrient release in clinoptilolite-phosphate rock (Cp-PR) systems occurs through dissolution and cation-exchange reactions. Investigating the kinetics of these reactions expands our understanding of nutrient release processes. Research was conducted to model transport kinetics of nutrient release in Cp-PR systems. The objectives were to identify empirical models that best describe NH4, K, and P release and define diffusion-controlling processes. Materials included a Texas clinoptilolite (Cp) and North Carolina phosphate rock (PR). A continuous-flow thin-disk technique was used. Models evaluated included zero order, first order, second order, parabolic diffusion, simplified Elovich, Elovich, and power function. The power-function, Elovich, and parabolic-diffusion models adequately described NH4, K, and P release. The power-function model was preferred because of its simplicity. Models indicated nutrient release was diffusion controlled. Primary transport processes controlling nutrient release for the time span observed were probably the result of a combination of several interacting transport mechanisms.

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