Coated Magnetic Nanoparticles for Acidic Nuclear Waste Separation
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Coated Magnetic Nanoparticles for Acidic Nuclear Waste Separation M. Kaur1, H. Han1, J. Kaczor2, A. Johnson2, A. Paszczynski2 and Y. Qiang1* 1 Department of Physics and Environmental Science, University of Idaho, Moscow, ID 83844, U.S.A. 2 Environmental Biotechnology Institute, University of Idaho, Moscow, ID 83844, U.S.A. * Corresponding author: [email protected] ABSTRACT Actinide specific chelator (che) conjugated with magnetic nanoparticles (MNPs) have been developed to separate nuclear waste in acidic conditions. Compared to the traditional nuclear waste treatments, such as solvent extraction and ion exchange, this method is a simple, compact and cost-effective process that generates minimum secondary waste. In this paper, we focus on the coating process of MNPs to achieve a combination of good acidic resistance, high chelator loading density and efficient magnetic separation. An optimized silica coating process before the chelator conjugates directly onto MNPs significantly improves the acidic resistance of the MNPche complex. Chelator loading density is significantly increased by attaching a linear polyamine polymer poly(allylamine hydrochloride) (PAH) to the surface of the MNPs using chemical and physical approaches. INTRODUCTION Magnetic nanoparticles (MNPs) have been used in a wide range of applications. From data storage to clinical applications, MNPs have become popular and are in great use due to their continuous reduction in size along with optimized magnetic properties of particles [1]. Recently, MNPs with large specific surface area become promising for separating nuclear High Level Waste (HLW) [2]. Conjugated with actinide specific chelators, the MNP-chelator complex can selectively adsorb the radioactive elements which can be collected magnetically [3]. After collection, the complex conjugate can be recycled by stripping the radioactive elements from the conjugates, generating a very small amount of secondary waste. The actinide separation method using MNPs functionalized with actinide specific chelators utilizes the separation capability of chelators and the ease of magnetic separation. This separation method eliminates the need of large quantities of organic solutions used in the traditional liquidliquid extraction process. The MNPs can be recycled for separation as they maintain the magnetic properties, thus this separation method greatly reduces the generation of secondary waste compared to liquid extraction technology. The recycling of MNPs makes this procedure more cost effective. The high diffusivity of MNPs and the large surface area also facilitate high efficiency of actinide sorption by the chelators. This method could help solve the nuclear waste remediation problem. Due to the highly acidic conditions found in most nuclear waste tanks, the MNPs are soluble in low pH solution. This would cause the MNPs to lose their magnetic properties making them unable to be used for magnetic separation. Therefore, an efficient coating method is required to protect the magnetic metal cor
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