Phase migration and transformation of uranium in mineralized immobilization by wasted bio-hydroxyapatite

In this work, phase migration and transformation of uranium were investigated to understand the mechanism of uranium immobilization on bio-hydroxyapatite (Bio-HAP(600)), in which waste fish bone was successfully converted into a novel Bio-HAP(600) by calcination at 600 degrees C. The physicochemical properties of Bio-HAP(600) were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier Transform Infrared Spectrometer (FTIR) analyses. Sorption behaviors were investigated by batch experiments in comparison with commercial nano HAP. Phase transformation and fate of uranium during sorption process were investigated by SEM mapping and XRD analysis. Results showed that sorption equilibrium of Bio-HAP(600) was achieved within 10 min. The maximum uranium sorption capacity of 384.6 mg/g was comparable to commercial available Nano-HAP. Chemical mineralization played a dominant role in the retention of uranium on Bio-HAP. Sorption of U (VI) was highly dependent on the content of P, Ca and O. Formation of nano flake crystal of autunite (Ca(UO2)(2)(PO4)(2)(H2O)(6)) was ascribed as the transformation and fate of uranium mineralization, contributing to the favorable immobilization of uranium. The results indicate that calcination of fish bone leading to Bio-HAP can be a feasible way to produce efficient uranium adsorbent for immobilizing uranium through forming nano flake crystals of autunite. (C) 2018 Elsevier Ltd. All rights reserved.