Adsorption of mixed metal systems on kaolinite

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Virginia Polytechnic Institute and State University


This study presents the results from laboratory investigations of the capacity of kaolinite to adsorb heavy metals including copper, nickel, cadmium, and lead. Kaolinite is a clay commonly found in suspended solids and sediments in natural water systems. The purpose of the study was to evaluate the validity of the competitive adsorption equation presented by weber in describing metal adsorption on kaolinite. This equation describes adsorption competition among the components of a mixture of solutes. Adsorption studies were conducted for single and mixed metal systems. Controlling factors considered include solution pH, clay dosage, and cation competition.

The investigation demonstrated that the competitive adsorption equation is a valid and useful equation for describing the adsorption of mixed metal systems on kaolinite. The equation may be used to predict equilibrium metal concentrations in mixed metal systems. The results of the study also indicated that the rate of adsorption of the metals on kaolinite was very rapid. Equilibrium was complete within thirty minutes of the addition of the metals to the clay.