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  • Author: C. Valdez x
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Abstract

The aim of this work is to discuss the relative contribution of homogeneous and heterogeneous Fenton processes in the treatment of Orange II dye solutions at pH 3 and 7 using an ion exchange resin as iron support. While at pH 3, 99% of the colour was removed, under neutral conditions a decoloration of 56% was observed. Studying the release of iron from the resin, we found a concentration of 1.49 mg/L of ferric ion and 0.31 mg/L of ferrous ion at pH 3 and 1.08 mg/L and 0.11 mg/L at pH 7, revealing that as expected, dissolution of iron ions at pH 3 is larger. Using these concentrations in a homogeneous process, 45% of the colour can be removed at pH 3 and 10% at pH 7, so it was infered that there is an effect of the iron that is still supported on the resin. In this way, a mixed homogeneous/heterogeneous mechanism could be proposed. While the experimental data for the desorption of iron at pH 3 was well suited to a pseudo second order kinetic model, the desorption of iron at pH 7 was fit to pseudo-first order kinetics. Experimental results of dye decolorization were on the other hand, fitted to a pseudo first order kinetics.

Abstract

Generator nuclides constitute a convenient tool for applications in nuclear medicine. In this paper, some radiochemical aspects of generator nuclide parents regularly processed at Los Alamos are introduced. The bulk production of the parent nuclides 68Ge, 82Sr, 109Cd and 88Zr using charged particle beams is discussed. Production nuclear reactions for these radioisotopes, and chemical separation procedures are presented. Experimental processing yields correspond to 80%-98% of the theoretical thick target yield. Reaction cross sections are modeled using the code ALICE-IPPE; it is observed that the model largely disagrees with experimental values for the nuclear processes treated. Radionuclide production batches are prepared 1-6 times yearly for sales. Batch activities range from 40 MBq to 75 GBq.

In December of 1989, the United States Food and Drug Administration approved 82Rb chloride in saline solution for cardiological perfusion imaging by positron emission tomography (PET). The solution is derived from a 82Sr generator system that is presently manufactured by Bristol Myers Squibb and distributed for clinical application in the United States by Bracco Diagnostics, Inc. Many years of research and development by people in several institutions led up to the approval for clinical use. Currently, there are about 15 sites in the U.S. that perform clinical myocardial perfusion imaging by PET using 82Rb chloride from the generator. In order to manufacture the generators, Bristol Myers Squibb requires about 1600 mCi of 82Sr every 30 days. The United States Department of Energy and MDS Nordion, Canada are the current suppliers with qualified Drug Master Files for the production and distribution of this nuclide for the Cardiogen® generator. These two entities have worked together over the years to assure the regular, reliable supply of the 82Sr. Here we describe the facilities and methods used by the Department of Energy in its Virtual Isotope Center to make and distribute the nuclide.