MODELING TRANSPORT KINETICS IN CLINOPTILOLITE PHOSPHATE ROCK SYSTEMS

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