Synthesis of Zirconia in Cement (Zir-Cem) and Study of Adsorption of EDTA on Zir-Cem

Abstract

The important problem to address in nuclear industries involves mitigation of the radioactive and corrosion products of nuclear reactor components. Even though physical and chemical methods lend a helping hand in solving this problem, the dominant method is by carrying out chemical cleaning. But this process results in the metal ions in complex state, not viable for treatment. To render the metal ions in the free state advanced oxidation process using oxidizing agents like ozone, Hydrogen peroxide, electro flotation, supercritical oxidation etc can be resorted . The decontaminating agents used are picolinic acid, EDTA, ascorbic acid, NTA etc. EDTA complex the metal ions but generate secondary waste with them. In our work, treatment of generated decontaminated waste using EDTA as decontaminant has been dealt with. From the literature, we understand that attempts have been made to degrade ethylene diamine tetraacetic acid using Fenton’s reagent in the presence of light [1]. This will facilitate the release of free radioactive ions for further treatment. In addition to chemical oxidation of EDTA, photochemical oxidation in presence of Zirconia and titania which generates electrons and positive ions for further oxidation has been reported [2]. In this paper, we have made an attempt to absorb the EDTA on zirconia loaded on white cement, study the adsorption characteristics which is the first step for photodegradation using UV light. Zirconium oxide was synthesized by the sol-gel method using Zirconium isopropoxide to water ratio 1:2 which resulted in powder by this process. This Powder was characterized for physical and chemical parameters before immobilizing with cement for adsorption. The system containing cement bonded to Zirconia (Zir-Cem) was subjected to removal of EDTA by adsorption. Since the zirconia powder as generated was found to have a high surface area compared to heat-treated (470oC and 720oC resulting in monoclinic and tetragonal crystalline forms) the as prepared zirconia was found to be the best candidate for efficient adsorption.