My Account: Log In | Join | Renew
Search
Author
Title
Vol.
Issue
Year
1st Page

Abstract

 

This article in SSSAJ

  1. Vol. 49 No. 4, p. 867-873
     
    Received: Sept 10, 1984
    Published: July, 1985


 View
 Download
 Alerts
 Permissions
 Share

doi:10.2136/sssaj1985.03615995004900040016x

Kinetics and Mechanisms of Aluminum Adsorption on Kaolinite Using a Two-site Nonequilibrium Transport Model1

  1. P. M. Jardine,
  2. J. C. Parker and
  3. L. W. Zelazny2

Abstract

Abstract

Kinetics of Al adsorption on Ca-kaolinite at selected concentrations, pH, and column lengths were studied using a miscible displacement technique. Observed breakthrough curves (BTC) for continuous injection of pH 4.3, 0.75 to 7.75 µg mL−1 Al solution were well-described by a two-site nonequilibrium transport model which assumes that sorption sites can be divided into two fractions: (1) instantaneous equilibrium sites and (2) sites following first-order reversible kinetics. Independent verification of the fitted parameter β, related to the fraction of type-1 equilibrium sites, was possible by assuming negative surface charge sites of kaolinite were in local equilibrium with the solution phase. Confirmation of the fitted parameter R, which is a measure of the total Al adsorbed, was not possible due to the nonsingular nature of the equilibrium adsorption isotherm. First-order rate coefficients (α) for Al adsorption on kaolinite were unaffected by column length. Effects of influent Al concentration on α were small but suggested that kinetic reaction of Al with kaolinite was not strictly first-order. Decreasing the pH of influent solution from 4.3 to 4.0, eliminated type-2 kinetic sites. These effects indicate that kinetic reactions involve Al polymerization on kaolinite while equilibrium reactions reflect Ca-Al exchange. This scenario is supported by Ca desorption data of the effluent and by potentiometric titrations of effluent solutions.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © . Soil Science Society of America