Electro-deposition of zinc and lead from their oxide compound using choline chloride and urea based ionic liquid

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University of Alabama Libraries

A novel method for electrodepositing metal such as zinc and lead was investigated by using a urea and choline chloride based ionic liquid as electrolyte at low temperature. The solubility analysis of both metal oxides in the resulting ionic liquid was investigated by comparing the absorption peak from FTIR. The solubility was illustrated as a function of temperature and amount of added metal oxide. Electrochemical behavior was measured from a three electrode cell which consisted of tungsten wire as cathode, platinum wire as anode and silver wire as quasireversible reference electrode using EG&G electrochemistry workstation setup. The reduction potential was found at -1.1V for the zinc system and -0.37V for the lead system, both used Ag as reference electrode. This study has been focused on measuring values of diffusion coefficient and charge transfer coefficient in different experimental conditions. In the Zn system, the charge transfer coefficient has been calculated in different temperature and found to be ranging from 0.180 to 0.258 while in the Pb system ranges from 0.528 to 0.627, and the diffusion coefficient from 1.14×10-7to 2.84×10-6 in the Zn system while 1.09×10-8to 1.42×10-7in the Pb system. The activation energy of diffusion of electro-active species in both systems are calculated and compared to a value of 107.23 kJ/mol in Zn to 124.70 kJ/mol in Pb. The nucleation mechanism was investigated for both systems. A three-dimensional nucleation model has been compared to experimental data. Instantaneous nucleation has been found for both systems. The electrodeposition for both Zn and Pb has been carried out on the Cu substrate in different voltages. Deposits are characterized by scanning electron microscopy (SEM) for morphology and X-ray diffraction (XRD) for structural analysis. Compositional analysis of both metal deposits on the cathode has been performed using Energy Dispersive Spectrometer (EDS). Metals in high purity were obtained. To improve the quality of deposited metal, effect of [BMIM]HSO4 an additive agent has been investigated. [BMIM]HSO4 has been shown to effectively improve surface layer quality by promoting a dense and uniform deposited film with finer particle size.

Electronic Thesis or Dissertation
Engineering, Materials science