Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics

Cyprian Murutu, Maurice S. Onyango, Aoyi Ochieng, Fred Otieno

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)

Abstract

Fluoride in drinking water above permissible levels is responsible for human dental and skeletal fluorosis. Adsorptive based defluoridation is the most popular technique with several end-user applications. Consequently, this paper describes the fluoride removal potential of a novel sorbent, limestone-derived apatite from drinking water. The adsorbent was prepared by calcining limestone followed by reacting with orthophosphoric acid. Batch sorption studies were performed as a function of contact time, pH, initial fluoride concentration, temperature and adsorbent dose. Sorption of fluoride was found to be pH dependent with a maximum occurring in the pH range of 5-9. The authors also observed that the material had a buffering effect on the same pH range. Meanwhile, the adsorption capacity was found to increase with temperature, depicting the endothermic nature of the adsorption process and decreases with adsorbent mass. The equilibrium data was well described by the conventional Langmuir isotherm, from which isotherm the maximum adsorption capacity was determined as 22.2 mg/g. From the kinetic perspective, the fluoride adsorptive reaction followed the pseudo-second order mechanism.
Original languageEnglish
Title of host publicationSustainable Policy Applications for Social Ecology and Development
EditorsElias G. Carayannis
PublisherIGI Global
Pages128-138
Number of pages11
ISBN (Electronic)9781466615878
DOIs
Publication statusPublished - 2012

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Apatites
Calcium Carbonate
Fluorides
Adsorption
Kinetics
Adsorbents
Drinking Water
Isotherms
Sorption
Sorbents
Temperature

Cite this

Murutu, C., Onyango, M. S., Ochieng, A., & Otieno, F. (2012). Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics. In E. G. Carayannis (Ed.), Sustainable Policy Applications for Social Ecology and Development (pp. 128-138). IGI Global. https://doi.org/10.4018/978-1-4666-1586-1.ch010
Murutu, Cyprian ; Onyango, Maurice S. ; Ochieng, Aoyi ; Otieno, Fred. / Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics. Sustainable Policy Applications for Social Ecology and Development. editor / Elias G. Carayannis. IGI Global, 2012. pp. 128-138
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Murutu, C, Onyango, MS, Ochieng, A & Otieno, F 2012, Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics. in EG Carayannis (ed.), Sustainable Policy Applications for Social Ecology and Development. IGI Global, pp. 128-138. https://doi.org/10.4018/978-1-4666-1586-1.ch010

Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics. / Murutu, Cyprian; Onyango, Maurice S.; Ochieng, Aoyi; Otieno, Fred.

Sustainable Policy Applications for Social Ecology and Development. ed. / Elias G. Carayannis. IGI Global, 2012. p. 128-138.

Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)

TY - CHAP

T1 - Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics

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AU - Otieno, Fred

PY - 2012

Y1 - 2012

N2 - Fluoride in drinking water above permissible levels is responsible for human dental and skeletal fluorosis. Adsorptive based defluoridation is the most popular technique with several end-user applications. Consequently, this paper describes the fluoride removal potential of a novel sorbent, limestone-derived apatite from drinking water. The adsorbent was prepared by calcining limestone followed by reacting with orthophosphoric acid. Batch sorption studies were performed as a function of contact time, pH, initial fluoride concentration, temperature and adsorbent dose. Sorption of fluoride was found to be pH dependent with a maximum occurring in the pH range of 5-9. The authors also observed that the material had a buffering effect on the same pH range. Meanwhile, the adsorption capacity was found to increase with temperature, depicting the endothermic nature of the adsorption process and decreases with adsorbent mass. The equilibrium data was well described by the conventional Langmuir isotherm, from which isotherm the maximum adsorption capacity was determined as 22.2 mg/g. From the kinetic perspective, the fluoride adsorptive reaction followed the pseudo-second order mechanism.

AB - Fluoride in drinking water above permissible levels is responsible for human dental and skeletal fluorosis. Adsorptive based defluoridation is the most popular technique with several end-user applications. Consequently, this paper describes the fluoride removal potential of a novel sorbent, limestone-derived apatite from drinking water. The adsorbent was prepared by calcining limestone followed by reacting with orthophosphoric acid. Batch sorption studies were performed as a function of contact time, pH, initial fluoride concentration, temperature and adsorbent dose. Sorption of fluoride was found to be pH dependent with a maximum occurring in the pH range of 5-9. The authors also observed that the material had a buffering effect on the same pH range. Meanwhile, the adsorption capacity was found to increase with temperature, depicting the endothermic nature of the adsorption process and decreases with adsorbent mass. The equilibrium data was well described by the conventional Langmuir isotherm, from which isotherm the maximum adsorption capacity was determined as 22.2 mg/g. From the kinetic perspective, the fluoride adsorptive reaction followed the pseudo-second order mechanism.

U2 - 10.4018/978-1-4666-1586-1.ch010

DO - 10.4018/978-1-4666-1586-1.ch010

M3 - Chapter (peer-reviewed)

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BT - Sustainable Policy Applications for Social Ecology and Development

A2 - Carayannis, Elias G.

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Murutu C, Onyango MS, Ochieng A, Otieno F. Adsorption of Fluoride on Limestone-Derived Apatite: Equilibrium and Kinetics. In Carayannis EG, editor, Sustainable Policy Applications for Social Ecology and Development. IGI Global. 2012. p. 128-138 https://doi.org/10.4018/978-1-4666-1586-1.ch010