Defluoridation of groundwater using aluminum-coated bauxite: Optimization of synthesis process conditions and equilibrium study

Abdulai Salifu, Branislav Petrusevski, Emmanuel S. Mwampashi, Iddi A. Pazi, Kebreab Ghebremichael, Richard Buamah, Cyril Aubry, Gary L. Amy, Maria D. Kenedy

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


There is no known effective treatment for fluoride-related health disorders, hence prevention through water defluoridation is necessary. This study explored the possibility of modifying the physico-chemical properties of bauxite, a locally available material in many countries including Ghana, by thermal treatment and an aluminum coating, for water defluoridation. The study mainly focused on investigating the effects of varying synthesis process conditions on the defluoridation efficiency of Granular Aluminum Coated Bauxite (GACB). GACB performed better than raw bauxite (RB) and was able to reduce fluoride concentration in groundwater from 5 ± 0.2 mg/L to ≤ 1.5 mg/L, World Health Organization (WHO) guideline. Based on nonlinear Chi-square (χ2) analysis, the best-fitting isotherm model for the fluoride-GACB system was in the order: Freundlich > Redlich-Perterson ≈ Langmuir > Temkin. The fluoride adsorption capacity of GACB (qmax = 12.29 mg/g) based on the Langmuir model was found to be either comparable or higher than the capacities of some reported fluoride adsorbents. Aluminum (Al) coating procedures optimized in this study could therefore be a useful approach for synthesizing an effective fluoride adsorbent using bauxite, a locally available material. Kinetic and isotherm analysis, thermodynamic calculations, as well as FTIR and Raman analysis suggested the mechanism of fluoride adsorption onto GACB was complex and involved both physical adsorption and chemisorption processes.

Original languageEnglish (US)
Pages (from-to)108-117
Number of pages10
JournalJournal of Environmental Management
StatePublished - Oct 1 2016

Bibliographical note

KAUST Repository Item: Exported on 2021-07-06
Acknowledgements: The authors are greatly indebted to the Dutch Government (DUPC, Program 1) project for financing this study. The authors are also thankful to Mr. Stefaan Heirman of TU Delft, for assistance with Raman spectroscopic analysis.


  • Adsorption
  • Aluminum
  • Bauxite
  • Fluoride
  • Groundwater defluoridation
  • Surface modification

ASJC Scopus subject areas

  • Environmental Engineering
  • Waste Management and Disposal
  • Management, Monitoring, Policy and Law


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