Environmentally benign and novel management route for radioactive corrosion products by hydroxyapatite

Efficient immobilization of ionic corrosion products by a silica-hydroxyapatite composite via a cold sintering route

“… 36 HAp is a well-known sorbent for trapping monovalent and divalent metal ions from aqueous media. 3,37,38 A detailed sorption study on the optimization of the HAp powder dose to remove a maximum amount of metal ions from a mixture may be found in our previous study. 3 Briefly, 40 g L −1 HAp powder was found sufficient to remove more than 95% of the metal ions (Co, Cr, Cu, Fe, Mn, Ni, and Zn) with a total concentration of 7 mM at pH 6.…”

“… 3,37,38 A detailed sorption study on the optimization of the HAp powder dose to remove a maximum amount of metal ions from a mixture may be found in our previous study. 3 Briefly, 40 g L −1 HAp powder was found sufficient to remove more than 95% of the metal ions (Co, Cr, Cu, Fe, Mn, Ni, and Zn) with a total concentration of 7 mM at pH 6. In another study, EDTA-Si was synthesized and applied to capture Co, Cu and Ni ions from aqueous solution.…”

“…Both constituents of the composite (EDTA-Si and HAp) are readily available and possess ion exchange properties. 3,18–21 HAp is the most important bioactive material with many natural sources in the form of minerals, phosphate-based rocks, and animal and fish bones. 22 It can easily be synthesized by co-precipitation, sonochemical and hydrothermal methods and is commercially available as well.…”

“…HAp was also studied and reported for its crystal structure flexibilities to incorporate and hold a number of cationic and anionic species. 3,24 Silica has been used as a thickening agent to reinforce and improve the mechanical properties of nanomaterials. 25 Silica-reinforced calcium hydroxyapatite has been synthesized for dentistry and biomedical applications.…”

“… 28–31 The immobilization of radioactive wastes by HAp has also been suggested elsewhere. 3,32 Nevertheless, the sorption, solid-state mixing, and solidification properties of two spent wastes (metal ion captured silica and HAp) are the least investigated. Additionally, high-temperature sintering has certain disadvantages, such as the volatilization of sorbed volatile radionuclides, the dehydroxylation of hydroxyapatite to form unwanted apatite phases (β-TCP), and the high processing cost.…”