Doctoral Degrees (Chemistry and Polymer Science)

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Browsing Doctoral Degrees (Chemistry and Polymer Science) by Author "Aardaneh, Khosro"

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    Separation of 103Pd from Ag and Rh targets for production of '103 Pd seeds' for prostate cancer brachytherapy
    (Stellenbosch : Stellenbosch University, 2002-12) Aardaneh, Khosro; Van der Walt, T. N.; Raubenheimer, H. G.; Stellenbosch University. Faculty of Science. Dept. of Chemistry & Polymer Science.
    ENGLISH ABSTRACT: Radiochemical separation of 103Pd from natAg, usmg a 66 MeV proton-induced reaction at iThemba LABS, was studied and a radiochemical method was developed for the separation. For the separation, which comprises the separation of Pd from a large amount of target material (16 g Ag), as well as Rh radioisotopes produced from decay of their Pd parents (mainly 101Rhand IOORh),three ion exchange resins were tested: a Chelex 100 chelating resin, the AG 1-X8 anion exchange resin and a AG MP-I anion exchange resin. For the optimum elution ofPd from the latter two resins, two elution curves using water and 5% ammonia solution, were obtained. With an average recovery of 97.4% and sharper elution curve from the macroporous AG MP-I, this resin was finally chosen for routine production. To achieve the separation, a simple, easily operated radiochemical processing system was designed and installed in a hot cell. Radiochemical separation of 103Pd from a Rh target was also studied and several cation and anion exchange resins were tested. A carrier-free separation of 103Pd was developed, using an AG 1-X8 anion exchange resin. Bombarded tablets of RhCh.3H20, as the targets, were used for these separations. The procedure, originally designed for the separation of Pd from Cu and Rh, was modified using H202 for the oxidation of Ru prior to the sorption on the resin and successfully used for the separation of isotopes of Rh from the isotopes of Pd, Ru, Tc, Nb, Mo, Zr and Y, which were produced by 400 MeV 160_ and 12C-induced RhCb.3H20 targets. To elute the Pd from the resin, 5% ammonia solution was used; the recovery was about 92%. To prepare the Rh target for routine production, an electroplating method of Rh on a Cu substrate was developed. Rh(CI04)3, in 0.5 M perchloric acid, was used as the electrolyte bath. The electroplated Rh was then dissolved by an alternating current technique, using 6 M HCI and a current density of 2 Alcm2. For production of the seeds, I03Pd was sorbed on the weakly basic anion exchange resin Amberlite IRA-93 (600-700 Il), by recycling a 0.5 M Hel solution of Pd through a 0.5 cm x 1 cm column for 2 hours. The distribution of I03Pd on the resin beads was measured and RSD of5.7% was obtained. A funnel was designed to transfer the I03Pd-loaded resin beads into the Ti tubes to prepare the seeds (0.7 mm LD., 0.8 mm D.D., and 4.5 mm length). To enclose the tubes as capsules, the end caps were made from 0.02 mm Ti sheet and several pieces were designed and machined for the welding of the caps to the tubes. A spotwelding machine was used for the welding, after small, but vital modifications.