Factors Governing the Performance of Bauxite for Fluoride Remediation of Groundwater

Factors Governing the Performance of Bauxite for Fluoride Remediation of Groundwater

TitleFactors Governing the Performance of Bauxite for Fluoride Remediation of Groundwater
Publication TypeJournal Article
Year of Publication2017
AuthorsKatya Cherukumilli, Caroline Delaire, Susan Amrose, Ashok J Gadgil
JournalEnvironmental Science & Technology
Volume51
Issue4
Pagination2321 - 2328
Date Published01/2017
ISSN0013-936X
Abstract

Globally, 200 million people drink groundwater contaminated with fluoride concentrations exceeding the World Health Organization’s recommended level (WHO-MCL = 1.5 mg F/L). This study investigates the use of minimally processed (dried/milled) bauxite ore as an inexpensive adsorbent for remediating fluoride-contaminated groundwater in resource-constrained areas. Adsorption experiments in synthetic groundwater using bauxites from Guinea, Ghana, U.S., and India as single-use batch dispersive media demonstrated that doses of ∼10–23 g/L could effectively remediate 10 mg F/L. To elucidate factors governing fluoride removal, bauxites were characterized using X-ray fluorescence, X-ray diffraction, gas-sorption analysis, and adsorption isotherms/envelopes. All ores contained gibbsite, had comparable surface areas (∼14–17 m2/g), had similar intrinsic affinities and capacities for fluoride, and did not leach harmful ions into product water. Fluoride uptake on bauxite -primarily through ion-exchange- was strongly pH-dependent, with highest removal occurring at pH 5.0–6.0. Dissolution of CaCO3, present in trace amounts in India bauxite, significantly hindered fluoride removal by increasing solution pH. We also showed that fluoride remediation with the best-performing Guinea bauxite was ∼23–33 times less expensive than with activated alumina. Overall, our results suggest that bauxite could be an affordable fluoride-remediation adsorbent with the potential to improve access to drinking water for millions living in developing countries.

DOI10.1021/acs.est.6b04601
Short TitleEnviron. Sci. Technol.
Refereed DesignationRefereed