Monovalent ion exchange kinetics of hydrated calcium-alumino layered double hydroxides

Guillermo Puerta-Falla, Magdalena Balonis, Gabriel Falzone, Mathieu Bauchy, Narayanan Neithalath, Gaurav Sant

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


This study reveals ion exchange kinetics in hydrated calcium-alumino layered double hydroxides of the alumino-ferrite monosubstituent (AFm) subgroup. By careful analysis of solution phase (ion) concentrations and the solid phases, the rate of exchange of NO3- for Cl- ions from the interlayer positions is studied across a range of temperature, solution compositions, and solution conditions (i.e., static and convectively mixed). Ion exchange kinetics conform to an exponential first-order reaction that follows an Arrhenius formalism. The activation energy of ion exchange is 38.2 ± 4.6 kJ/mol for exchange occurring in the thermodynamically preferred (i.e., NO3- for Cl- ion exchange) direction and it is 1.8 times greater for the inverse less-preferred pathway. For ion exchange occurring in the favored direction NO3-AFm converts to Cl-AFm; whereas in the disfavored (less-favored) direction, the compositional change occurs in two steps with the formation of a Cl-NO3-AFm solid solution as an intermediate step; before Cl- species are exhausted and NO3-AFm forms as the product. By comparison of ion exchange rates in static and mixed solutions, transport through the Nernst diffusion layer (NDL) is identified as the rate-limiting step in ion exchange kinetics. (Graph Presented).

Original languageEnglish (US)
Pages (from-to)63-74
Number of pages12
JournalIndustrial and Engineering Chemistry Research
Issue number1
StatePublished - Jan 11 2017

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


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