Research On Preparation And Property Of Modification Hydroxyapatite

In this dissertation, The nano-hydroxyapatite powder (HAP) was prepared by sol-gel method. This study focuses on the investigation of adsorption of copper and cadmium ions from aqu(?)u solution on the HAP. Some parameters that determine heavy metal ions removal incluc(?) contact time, adsorbent dose, pH value, the solution temperature and initial concent(?)on were evaluated. The sorption isotherm was studied. The kinetic process of heavy metal io(?)sorption onto the synthesized HAP was tested by applying the pseudo-first order, the pseudo-sec(?)nd order, the simple Elovich and intraparticle diffusion rate models. The mec(?)heavy metal ions removal was also studied. The HAP was adulterated with C(?)ubes (CNTs) to prepare CNTs/HAP composite material. The property of this ma(?)heavy metals was studied.W(?)were prepared by sol-gel method with Ca (NO3)2·4H2O and H3PO4precursors. HA(?).vaer ana sintered compact were analyzed and characterized by differential thermal analysis, X-ray diffractometry, and scanning electron microscope. The density was measured by Archimedes drainage method. It was shown that the powder was spherical with very little reunion and the particle size distributed uniform. The grain sizes in a-axis and c-axis direction were10-30nm and20-50nm respectively. The particle size and crystallization percent increased with the increase of temperature. HAP sintered at600℃for2h was of high purity and good crystallization. There was a small amount of Ca3(PO4)and CaO in the HAP sintered at800℃and900℃, which was due to the HAP decomposition and the phosphorous volatilization. This sol-gel process can be used to prepare nano-HAP with high purity, different particle size and crystallization percentage.The results of copper and cadmium ions removal using the HAP showed that the HAP was effective in removing Cu2+and Cd2+from aqueous solutions. The experimental results shown (?)efficiency of Cu2+was about99.24%at pH3,40℃, contact time60min, adsorbent dose of5g/L and initial concentration of60mg/L. The adsorption isotherm of Cu2+could be well defined by Langmuir equation. The removal efficiency of Cd2+was about99.42%at pH7,25℃, contact time60min, adsorbent dose of5g/L and initial concentration of60mg/L. The adsorption isotherm of Cd2+could be well defined by Langmuir and Freundlich equation.The competitive adsorption of copper and cadmium ions from aqueous solutions was studied in binary systems. The order of adsorption competitive was following:Cu2+>Cd2+, the Cu2+has an inhibition against Cd2+in binary systems. The result of sorption kinetics revealed that the sorption process of Cu2+and Cd2+removal on HAP follows a pseudo-second order kinetics with a contribution of intraparticle diffusion. The sorption process of Cu2+and Cd2+was complexly which consisted of two steps:the first step is related to external surface-sorption and sorption occurs instantaneously, the second step correlates with ion-exchange is a slow gradual sorption process.The result of CNTs alone adsorb heavy metals revealed that CNTs has a low capability of remove heavy metals, but in contrast the adsorption competitive Cu2+>Cd2+. The removal efficiency of CNTs/HAP composite material was higher than HAP and5wt was higher than lwt%. The result of CNTs/HAP composite material removed an admixture of heavy metals illuminated that It has a good removal efficiency for Cu2+in binary systems, which even higher than HAP alone adsorb Cu2+. However, the removal efficiency of Cd2+was lower than HAP, which is due to the low adsorption capability of CNTs for Cd2+and there exist an adsorption competitive (Cu2+>Cd2+) in mixed heavy metal solution.