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Title: Defluoridation chemistry of synthetic hydroxyapatite at nano scale: equilibrium and kinetic studies. Author: Sundaram CS, Viswanathan N, Meenakshi S. Journal: J Hazard Mater; 2008 Jun 30; 155(1-2):206-15. PubMed ID: 18162304. Abstract: This study describes the advantages of nano-hydroxyapatite (n-HAp), a cost effective sorbent for fluoride removal. n-HAp possesses a maximum defluoridation capacity [DC] of 1845 mg F(-)/kg which is comparable with that of activated alumina, a defluoridation agent commonly used in the indigenous defluoridation technology. A new mechanism of fluoride removal by n-HAp was proposed in which it is established that this material removes fluoride by both ion-exchange and adsorption process. The n-HAp and fluoride-sorbed n-HAp were characterized using XRD, FTIR and TEM studies. The fluoride sorption was reasonably explained with Langmuir, Freundlich and Redlich-Peterson isotherms. Thermodynamic parameters such as DeltaG degrees , DeltaH degrees , DeltaS degrees and Ea were calculated in order to understand the nature of sorption process. The sorption process was found to be controlled by pseudo-second-order and pore diffusion models. Field studies were carried out with the fluoride containing water sample collected from a nearby fluoride endemic area in order to test the suitability of n-HAp material as a defluoridating agent at field condition.[Abstract] [Full Text] [Related] [New Search]