African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1071

Full Length Research Paper

A comparative study of the defluoridation efficiency of synthetic dicalcium phosphate dihydrate (DCPD) and lacunar hydroxyapatite (L-HAp): An application of synthetic solution and Koundoumawa field water

A. S. Manzola
  • A. S. Manzola
  • Laboratoire de Chimie Analytique et Minérale, Faculté des Sciences et Techniques, Université Abdou Moumouni BP 10662, Niamey, Niger
  • Google Scholar
M. S. Laouali
  • M. S. Laouali
  • Laboratoire de Chimie Analytique et Minérale, Faculté des Sciences et Techniques, Université Abdou Moumouni BP 10662, Niamey, Niger
  • Google Scholar
M. Ben Amor
  • M. Ben Amor
  • Laboratoire des Traitements des Eaux Naturelles, CERTE, Technopôle de Borj Cedria, BP 273, 8020, Soliman, Tunisia
  • Google Scholar


  •  Received: 10 December 2014
  •  Accepted: 30 December 2014
  •  Published: 08 February 2015

Abstract

This paper deals with the comparison of defluoridation efficiency of two defluoridation agents by the use of dicalcium phosphate dihydrate (DCPD) and lacunar hydroxyapatite (L-Hap) as a fluoride sorbents. The DCPD and L-HAp are characterized by using XRD and FTIR techniques. Defluoridation of synthetic solution of sodium fluoride (NaF) and natural waters of Koudoumawa are studied. The fluoride removal capacity is as follows: DCPD: (26.37 mg.g-1; 0.0174 g, 9.81 mg.g-1; 0.1012 g) and L-Hap: (18.96 mg.g-1; 0.0174 g, 8.00 mg.g-1; 0.1012 g). The optimum 0.0623 g of DCPD/100 mL dosage of synthetic solution could bring down the level of fluoride within the tolerance limit, [F-] = 0.38 mg/l (WHO guideline value = 0.8 mg/l), the pH rise is 5.10 and the defluoridation time is 72 h. For L-Hap, it is 0.1012 g of L-Hap/100 mL, [F-] = 1.98 mg/l in the same conditions. For Koundoumawa natural waters, 0.0527 g of L-Hap/100 mL of solution could bring down the level of fluoride, [F-] = 0.84 mg/l. New mechanisms of fluoride removal by DCPD and L-HAp are proposed from which it is established that this material removes fluoride by ion-exchange, adsorption process, dissolution, precipitation and co-precipitation. 
 
Key words: Defluoridation, dicalcium phosphate dihydrate (DCPD), lacunar hydroxyapatite (L-Hap), adsorption, ion-exchange, dissolution-precipitation.