Experimental design and batch experiments for optimization of Cr(VI) removal from aqueous solutions by hydrous cerium oxide nanoparticles

Ahmad B. Albadarin*, Zheyu Yang, Chirangano Mangwandi, Yoann Glocheux, Gavin Walker, M. N. M. Ahmad

*Corresponding author for this work

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Hydrous cerium oxide (HCO) was synthesized by intercalation of solutions of cerium(III) nitrate and sodium hydroxide and evaluated as an adsorbent for the removal of hexavalent chromium from aqueous solutions. Simple batch experiments and a 25 factorial experimental design were employed to screen the variables affecting Cr(VI) removal efficiency. The effects of the process variables; solution pH, initial Cr(VI) concentration, temperature, adsorbent dose and ionic strength were examined. Using the experimental results, a linear mathematical model representing the influence of the different variables and their interactions was obtained. Analysis of variance (ANOVA) demonstrated that Cr(VI) adsorption significantly increases with decreased solution pH, initial concentration and amount of adsorbent used (dose), but slightly decreased with an increase in temperature and ionic strength. The optimization study indicates 99% as the maximum removal at pH 2, 20 °C, 1.923 mM of metal concentration and a sorbent dose of 4 g/dm3. At these optimal conditions, Langmuir, Freundlich and Redlich–Peterson isotherm models were obtained. The maximum adsorption capacity of Cr(VI) adsorbed by HCO was 0.828 mmol/g, calculated by the Langmuir isotherm model. Desorption of chromium indicated that the HCO adsorbent can be regenerated using NaOH solution 0.1 M (up to 85%). The adsorption interactions between the surface sites of HCO and the Cr(VI) ions were found to be a combined effect of both anion exchange and surface complexation with the formation of an inner-sphere complex.

Original languageEnglish
Pages (from-to)1354-1362
Number of pages9
JournalChemical Engineering Research and Design
Volume92
Issue number7
DOIs
Publication statusPublished - Jul 2014

Keywords

  • Adsorption isotherm
  • Chromium
  • Desorption
  • Hydrous cerium oxide
  • Nanoparticles
  • Optimization

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)

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