No abstract

Ionic liquids have shown to be environmental friendly electrolytes that are suitable for electrodeposition of metals. In this work, lead oxide (PbO) was dissolved in 2:1 mole ratio of urea/choline chloride (Urea/ChCl) eutectic mixture at different temperatures (343 to 363 K). Electrochemical measurement confirms that the reduction peak potential for Pb (II) to Pb at -0.43 V vs. Ag reference electrode. The reduction of Pb (II) to Pb is characterized as an irreversible process and controlled by diffusion of electroactive species in the electrolyte. The value of diffusion coefficient varies between 1.09 × 10 −8 and 1.42 × 10 −7 cm 2 /s at temperatures from 343 to 363 K, respectively. The activation energy of the reaction is 124.7 kJ/mol. Three-dimensional (3D) instantaneous nucleation and growth process is predominant at reduction potentials studied. The SEM images of the electrodeposits obtained at -0.5 to -1.1 V show dendritic-type morphology of Pb particles. The XRD and EDS analysis confirm that the electrodeposits are consisted of high-pure Pb metal.Lead is well-known for its unique physical properties such as malleability, high density, and high corrosion-resistance. Because of these properties, lead is widely used in industries for weighting, shielding, soldering, fishing-net sinkers and lead-acid storage batteries. 1 Traditionally, Pb is extracted from sulfide mineral ore of lead i.e., galena (PbS). The ore is mined and beneficiated by flotation methods that produces mineral concentrates. The wet concentrates are roasted in hot air and subsequently undergoes oxidation to form lead oxides. Finally, the Pb metal is produced by heating PbO in coke-fired blast furnace. 2,3 However, the traditional approach of Pb production is very sensitive to impurities and need rigorous purification steps to obtain pure Pb metal.Abbott et al., introduced the concept of deep eutectic solvents (DES) and showed that DES have remarkable ability to dissolve different metal oxides. 4,5 The authors reported that quaternary ammonium salts exists in liquid form at ambient temperatures after mixing with hydrogen bond donors. In current study, eutectic mixture of urea and choline chloride (2:1 molar ratio) is considered as electrolyte because of (i) low melting point (∼285 K) suitable for low temperature applications, (ii) comparatively wide electrochemical window (2.5 V) and (iii) relatively cheaper price. In addition, the ability of Urea/ChCl (2:1 molar ratio) to selectively dissolve metal oxides can simplify the electrodeposition of metal(s) from the electrolyte. Reports on metal oxide solubility in Urea/ChCl (2:1 molar ratio) at 333 K indicates that only Cu 2 O, PbO 2 , ZnO showed appreciable solubility, while other metal oxides such as Al 2 O 3 and CaO have negligible solubility in the electrolyte. 6 In our previous experiments, ZnO showed significant solubility (≤1.23 M) in Urea/ChCl (2:1 molar ratio) at 373 K. Although, DES and traditional ionic liquids (ILs) have similar properties such as good conductivity and low vapor pressure...

No abstract

No abstract

No abstract