Ion exchange studies on natural and modified zeolites and the concept of exchange site accessibility

Vassilis J. Inglezakis, Maria M. Loizidou, Helen P. Grigoropoulou

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122 Citations (Scopus)

Abstract

In the present study natural and Na-rich form of clinoptilolite are examined, in respect to ion exchange of Pb2+, Cu2+, Cr3+, and Fe3+. Equilibrium and kinetic studies performed, under the same normality (0.01 N). Equilibrium studies demonstrate that Na + enrichment of clinoptilolite is beneficial in respect to metal uptake for all metals, except Cr3+, which is shown to have the same equilibrium behavior in both materials. Kinetic study shows that diffusion coefficients are in the range of 0.16 to 9×10-9 cm 2/s, and are not always improved in Na-rich form of clinoptilolite. The effect of temperature on diffusion coefficients is also examined, and Arrhenius activation energy is determined to be in the range of 3.02 to 13.9 kcal/mol, for all metals and materials, except Cu2+, which have extremely low activation energy in the natural sample, equal to 0.04 kcal/mol.

Original languageEnglish
Pages (from-to)570-576
Number of pages7
JournalJournal of Colloid and Interface Science
Volume275
Issue number2
DOIs
Publication statusPublished - 15 Jul 2004

Keywords

  • activation energy
  • clinoptilolite
  • diffusion coefficients
  • distribution coefficients
  • heavy metals
  • ion exchange

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