Application of Alternating Current Electrochemical Dissolved Rhodium Target in Preparation of ¹⁰³Pd

Brachytherapy is an important radiotherapy technique that precisely targets tumors, offering advantages that cannot be replaced in terms of enhancing therapeutic efficacy, shortening treatment duration, and reducing side effects. ¹⁰³Pd, due to its unique decay properties, has broad application prospects in brachytherapy radiotherapy for prostate cancer and other solid tumors. There are various methods for preparing ¹⁰³Pd, and the most widely used one is to generate ¹⁰³Pd through the nuclear reaction of proton irradiation of ¹⁰³Rh(p, n)¹⁰³Pd using an accelerator. ¹⁰³Pd is embedded in rhodium targets in atomic state, forming a solid solution with rhodium. To obtain a solution of the ¹⁰³Pd nuclide, the rhodium target needs to be dissolved. Rhodium belongs to the platinum group metals, and due to its special electronic structure(close to a fully filled d orbital), high ionization energy, surface passivation ability, and tight crystal structure, it exhibits excellent antioxidant and corrosion resistance properties. Therefore, the efficient dissolution of the rhodium target has become a challenge in the preparation of ¹⁰³Pd. To solve this problem, the research on the electrochemical dissolution process of rhodium using alternating current was conducted. Based on the self-designed alternating current electrochemical dissolution system, the effects of process parameters such as alternating voltage, electrolysis temperature, hydrochloric acid concentration, metal rhodium grinding conditions(rhodium particle size), and electrochemical dissolution time on the dissolution rate of rhodium were investigated, and the optimal parameters were obtained. The results show that at 60 V alternating voltage, 100 ℃ electrolysis temperature, with 6 mol/L hydrochloric acid concentration, adding metal rhodium at a grinding speed of 1800 r/min for 4 minutes, and single dissolution for 30 minutes, the dissolution rate of rhodium can reach 28.9%. By replacing the electrolyte with the alternating current electrochemical dissolution system and repeating the dissolution 5 times, the dissolution rate of rhodium can reach over 95%. This simple method operates without high-temperature/pressure equipment or introducing new impurities, facilitating the automation of rhodium target dissolution. The target solution is transferred to the AG1-X8 anion exchange resin through the alternating current electrochemical dissolution system for the separation and purification of the target nuclide ¹⁰³Pd. First, Rh is washed with 6 mol/L hydrochloric acid to separate Rh from Pd, then Fe, Cu, Zn and other impurities are washed with 0.03 mol/L hydrochloric acid, and finally ¹⁰³Pd is desorbed using a mixed solution of ammonium chloride-ammonia water(volume ratio 1∶1), enabling the batch production of ¹⁰³Pd nuclides and providing a stable and reliable source of nuclides for the research and development of palladium ¹⁰³Pd brachytherapy seeds.