The Study On Preparation Of Nano-hydroxyapatite Powders And Adsorption Of Phenolic Compounds From Aqueous Onto Them

As main mineral components of bone and teeth of bamniote , nano Hydroxyapatite (n-HAp) has good biological compatibility and activity. It is non-toxic to human body and environment. Numerous studies have been carried out to investigate the organism renovation, adsorbing metal ions, transfering drug and protein molecules, but few studies have investigated the adsorption capability of phenolic compounds onto n-HAp.This paper mainly includes three parts as follows:1) Study of preparation of n-HAp powders via chemical precipitationThe n-HAp powders were prepared by chemical precipitation and characterized by many testing methods. Results showed that the powders were rod-like morphology with a size of about 25xl33nm, and dispersed well and no coalescence, and there were no impurity morphology in them. After calcined in 900°C or above, the powders lost their hydroxys, and become coalescence.2) Study on adsorption of phenol from aqueous onto n-HApThe affections of factors on adsorption were studied singly and ortho-experiment, and indicated that the affection of pH was biggest in all factors investigated. And the influence degrees were: pH > calcining temperature> adsorption temperature> adsorption time. Under acidic and alkaline, the amount of adsorption were bigger than normal, and the amount was maximum when pH=10. The adsorption of phenol onto powders accorded with the Freundlich model and the second adsorption model, and the process was endothermal. So increasing temperature could improve the spend of diffuse and remove effect of phenol from aqueous.3) Study on adsorption of phenolic compounds from aqueous onto n-HApThe experiment investigated the effects of remove phenolic compounds from aqueous by n-HAp. And used the equations of Freundlich and Langmuir fitting linear the adsorption isotherm, and caculated the ΔH~° , ΔG~° and ΔS~°. The results showed that the adsorb capabilities of catechol, p-aminophenol and p-chlorophenol were much bigger than others. The adsorb amounts of phenolic were increasing while the groups have stronger electron-donating ability. And increasing temperature could improve the adsorb effect of phenol, catechol, p-aminophenol and m-nitrophenol, while m-cresol, 3,5-xylenol and p-methoxyphenol were reduced. The adsorb processes of phenolic onto n-HAp were spontaneous and physical bonds.