Nucleation, growth and dissolution behaviour of galvanostatically deposited Sb/Sb-oxide on carbon steel

Abstract

Effective removal of radioactive Sb is a major concern during decontamination of structural materials in nuclear reactors. Galvanostatic deposition under different pH conditions was used to simulate Sb deposit on carbon steel. The difference in nucleation, growth and type of Sb species on carbon steel under different deposition conditions were studied by morphological, structural, compositional and electrochemical characterizations. Electrochemical nucleation over-potential and pH at the electrode interface were found to play dominant roles in deciding the growth pattern and the type of deposition. At low pH, elemental Sb was dominant, whereas the oxide form dominated at higher pH. Open circuit potential measurements and dissolution experiments on the deposits formed with complexing agents used in decontamination showed a difference in surface modification. This results in, incomplete removal of Sb from carbon steel surface, revealing the inadequacy in Sb decontamination using only chelants and the need for employing oxidizing agents in tandem.