Adsorption of citric acid from dilute aqueous solutions by hydroxyapatite

  • Vega E
  • Narda G
  • Ferretti F
  • 21


    Mendeley users who have this article in their library.
  • 20


    Citations of this article.


The role of citric acid in the demineralization of dental enamel, which is mainly constituted by hydroxyapatite, is important for periodontal regeneration and in the conditioning of enamel or dentin for bonding restorative resins. The adsorption of citric acid from aqueous solutions onto synthetic hydroxyapatite at 278, 288, 298, and 308 K and pH 4.8 has been studied by means of UV spectroscopy. The adsorption reaction, which takes place by an interaction between phosphate groups and citrate anions at the solid-solution interface, yields an adsorbate-adsorbent complex of high stability. The adsorption isotherms fit the Langmuirian shape. The proposed adsorption model, where citrate species interact in a bidentate manner (one citrate ion links two phosphate sites), is coherent with the experimental data. The activation standard heat and activation standard entropy were calculated. All the thermodynamic and kinetic parameters were in concordance with the adsorption reaction proposed in this work. © 2003 Elsevier Inc. All rights reserved.

Author-supplied keywords

  • Adsorption
  • Adsorption complex
  • Citric acid
  • Hydroxyapatite
  • Isotherms
  • Solid-liquid interactions

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document


  • Enrique D. Vega

  • Griselda E. Narda

  • Ferdinando H. Ferretti

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free