Sorptivity of Cd, Co and Pb on Soil, Montmorillonite and CaCO3 under Effect of their Different Concentrations in Equilibrium Solution

Document Type : Original Article

Abstract

SORPTIVITY, as a reliable mechanism for reducing the availability of.heavy metal, was investigated on two soils, i.e., Typic Torriorthent and Typic Haplocalcid, montmorillonite clay mineral and calcium carbonate. Three series of Cd, Co and Pb concentrations were equilibrated with each of the abovementioned adsorbents and the adsorption data were fitted to Langmuir, Van Bemmelen-Freundlich and Van-Huay adsorption isotherms. The results indicate that the studied isotherms could successfully describe the adsorption data. Maximum adsorption values calculated from Langmuir equation for Cd and Pb were lower in Typic Torriorthent soil than Typic Haplocalcid soil, whereas no obvious difference was detected for Co between the two investigated soils. Also, adsorption maxima for all the studied metal ions were found to be higher onntmorillonite clay mineral than on calcium carbonate. The binding energy values of the Typic Haplocalcid soil were higher than the corresponding ones of the Typic Torriorthent soil for both Co and Pb, while the opposite was true in case of Cd. Values of the binding energy for Cd, Co and Pb on CaCO3 component seemed obviously higher than the corresponding ones on the montmorillonite clay mineral. Van-Huay equation showed that the Typic Haplocalcid soil affinity constants for Cd, Co and Pb were higher than the corresponding ones of the Typic Torriorthent soil. Although, the parameters calculated from Van Bemmelen-Freundlich equation have no certain indications, yet their positive values confirm the fitness of this equation to describe adsorption data of Cd, Co and Pb on the investigated adsorbents.

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History

  • Receive Date: 26 June 2013
  • Revise Date: 23 July 2013
  • Accept Date: 24 July 2013

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