Study of kinetics and mechanism of uranium sorption onto nano Hydroxy-Apatite

The aim of the research work is to study the kinetics and mechanism of U sorption onto Nano hydroxy-apatite (HAP). For the study neat Nano HAP was synthesised in laboratory by wet chemical method taking (NH₄)₂HPO4 and Ca(NO₃)₂·4H₂O as precursor. The synthesised HAP was characterised using XRD, FT-IR and TEM. The Ca/ P ratio was confirmed using EDS data. The adsorption isotherms data was analysed using both Langmuir and Freundlich models in order to identify the best fit model and also to understand the process of sorption. The adsorption isotherm parameters are presented, according to the R2 values of the isotherm plots the sorption data are fit well to both the models but preferable Freundlich. This revealed that, the sorption capacity of the material is too high in comparison to spiked concentration. Hence sorption is multilayer adsorption on heterogeneous surface. A variation in the slope between 0 and 1 (n=0.337) indicates that the sorption process follows chemisorption process. The study revealed that sorption of U ion on HAP follows pseudo 2^nd order kinetics and is a multilayer adsorption process on heterogeneous surface