Influence of the anion nature and the metal-to-additive ratio on the effectiveness of ε-caprolactam during cadmium electrodeposition

The effect of the ε-caprolactam on the kinetics of the cadmium separation is traced within the wide range of the metal-additive ratios. The water solutions of 10''-''1 M LiClO4+yCd(ClO4)2 and 10''-''1 M LiI+yCdI2, where y=10''-''2, 5x10''-''2 and 10''-''1 mol/l, containing the ε-caprolactam as an additive, is traced. It is shown, that the ε-caprolactam in the perchlorate electrolytes accelerates the Cd''2''+ ions reduction within the whole studied range of the metal salt-additive ratios. By replacing the perchlorate anions through the iodide anions the rate of the process of the cadmium electrolytic reduction increases. Depending on the anion nature and the metal-additive ratios the ε-caprolactam acts in the role of either the bridge ligand or the effective inhibitor of the cadmium ions (2) electrodeposition process. In the latter case the uniform elastic metalloorganic coatings are formed on the cathode