Removal of fluoride ions from aqueous solution at low pH using schwertmannite

Journal article

Authors/Editors

Ochieng, Aoyi

Research Areas

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Publication Details

Author list: Eskandarpour A, Onyango MS, Ochieng A, Asai S

Publisher: Elsevier

Place: AMSTERDAM

Publication year: 2008

Journal: Journal of Hazardous Materials (0304-3894)

Journal acronym: J HAZARD MATER

Volume number: 152

Issue number: 2

Start page: 571

End page: 579

Number of pages: 9

ISSN: 0304-3894

eISSN: 1873-3336

Languages: English-Great Britain (EN-GB)

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Abstract

Wastewater containing fluoride requires polishing after precipitation/coagulation treatment in order to meet stringent environmental legislation. Accordingly, adsorption characteristics of fluoride onto schwertmannite adsorbent were studied in a batch system with respect to changes in initial concentration of fluoride, equilibrium pH of sample solution, adsorbent dosage and co-existing ions. Equilibrium adsorption data were obtained at 295.6, 303 and 313 K, and are interpreted in terms of two-site Langmuir, Freundlich, Langmuir-Freundlich, Redlich-Peterson, Toth and Dubinin-Radushkevitch isotherm models. The experimental and equilibrium modeling results revealed that the capacity of schwertmannite for fluoride is high but insensitive to changes in solution temperature. An increase in equilibrium pH of sample solution reduced significantly the fluoride removal efficiency. In binary component systems, inner-sphere complex forming species had negative effects on fluoride adsorption while outer-sphere complex forming species improved slightly the fluoride removal efficiency. The schwertmannite adsorbent was regenerable and had the ability to lower the fluoride concentration to acceptable levels.(c) 2007 Elsevier B.V. All rights reserved.

Keywords

Adsorption, fluoride, polishing, removal, schwertmannite, treatment, wastewater

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