Factors Governing the Performance of Bauxite for Fluoride Remediation of Groundwater

Date Published
01/2017
Publication Type
Journal Article
Authors
DOI
10.1021/acs.est.6b04601
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.

Journal
Environmental Science & Technology
Volume
51
Year of Publication
2017
Issue
4
Pagination
2321 - 2328
ISSN Number
0013-936X
Short Title
Environ. Sci. Technol.
Refereed Designation
Refereed
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