Defluoridation chemistry of synthetic hydroxyapatite at nano scale: Equilibrium and kinetic studies

作者：Sundaram C Sairam; Viswanathan Natrayasamy; Meenakshi S^*

来源：Journal of Hazardous Materials, 2008, 155(1-2): 206-215.

DOI：10.1016/j.jhazmat.2007.11.048

• defluoridation
• n-HAp
• Langmuir
• Freundlich
• Redlich-Peterson
• pseudo-first-order
• pseudo-second-order
• particle and pore diffusion
• adsorption
• ion-exchange

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 Delta G degrees, Delta H degrees, Delta S degrees and E-a 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.

• 出版日期2008-6-30