Factors Governing the Performance of Bauxite for Fluoride Remediation of Groundwater.
Environ Sci Technol
; 51(4): 2321-2328, 2017 02 21.
Article
in En
| MEDLINE
| ID: mdl-28106988
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 â¼10-23 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 (â¼14-17 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 â¼23-33 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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Aluminum Oxide
/
Fluorides
Language:
En
Journal:
Environ Sci Technol
Year:
2017
Document type:
Article
Affiliation country:
United States