This paper describes an experimental and modeling analysis of cadmium and zinc adsorption from aqueous solutions in single and binary systems on activated carbon. Batch tests were performed at constant pH (6.8 ± 0.3) and temperature (20 °C), in order to assess the adsorption capacity in experimental conditions simulating real wastewater. In particular, binary tests were carried out at same pH and temperature, with different initial concentration ratios of the two analytes, in order to emphasize the competition phenomena while minimizing the effect of pH. Experimental results indicate that zinc is adsorbed to a greater extent than cadmium, both in single and binary systems. In binary systems, zinc adsorption capacity is not influenced by the presence of cadmium, regardless of its concentration. On the contrary, an increase in zinc concentration in solution brings about a decrease in cadmium adsorption capacity. The experiments were interpreted by using both the rigorous and the extended Langmuir multicomponent adsorption isotherms and the Vacancy Solution Theory. The latter provided a satisfactory and simultaneous description of the experimental data for both zinc and cadmium adsorption, also accounting for the possible interactions between the two analytes and between the solvent (water) and the single analyte. © 2015, Springer Science+Business Media New York.

Modeling of single and competitive adsorption of cadmium and zinc onto activated carbon

ERTO, ALESSANDRO;DI NATALE, Francesco;LANCIA, AMEDEO
2015

Abstract

This paper describes an experimental and modeling analysis of cadmium and zinc adsorption from aqueous solutions in single and binary systems on activated carbon. Batch tests were performed at constant pH (6.8 ± 0.3) and temperature (20 °C), in order to assess the adsorption capacity in experimental conditions simulating real wastewater. In particular, binary tests were carried out at same pH and temperature, with different initial concentration ratios of the two analytes, in order to emphasize the competition phenomena while minimizing the effect of pH. Experimental results indicate that zinc is adsorbed to a greater extent than cadmium, both in single and binary systems. In binary systems, zinc adsorption capacity is not influenced by the presence of cadmium, regardless of its concentration. On the contrary, an increase in zinc concentration in solution brings about a decrease in cadmium adsorption capacity. The experiments were interpreted by using both the rigorous and the extended Langmuir multicomponent adsorption isotherms and the Vacancy Solution Theory. The latter provided a satisfactory and simultaneous description of the experimental data for both zinc and cadmium adsorption, also accounting for the possible interactions between the two analytes and between the solvent (water) and the single analyte. © 2015, Springer Science+Business Media New York.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11588/618519
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