Effect of Thiourea Containing Composite Additives on Nickel Electrodeposition in Ammoniacal Solution

Composite additives have an important influence on the process of metal electrodeposition and the quality of a metal deposited layer. In this work, the additive thiourea (TU) was compounded with cetyltrimethyl ammonium chloride (CTAC), sodium dodecyl sulfate (SDS) and polyethylene glycol 20,000 (PEG20000), and their effect on the cyclic voltammetric behavior, electrochemical nucleation mechanism, crystallographic orientations and surface morphology of the nickel electrodeposition in ammoniacal solution were experimentally investigated. The results show that the introduction of composite additives resulted in a stronger cathodic polarization and increased the nucleation overpotential (NOP) values significantly, which had an important impact on forming compact and smooth nickel deposits. The chronoamperometry analysis indicated that the reduction in nickel followed the 3D progressive nucleation mechanism in the presence of composite additives at the step potential of −1.16 V and −1.18 V. Smoother and finer nickel films were found using scanning electron microscopy (SEM) images as the composite additives were used. X-ray diffraction revealed that all nickel deposit samples had the face-centered cubic structure, and five main crystal planes were displayed by the presence of composite additives in the electrolyte. Furthermore, the diffraction peaks of (111) and (200) crystal planes were slightly shifted toward lower 2θ values when thiourea was used in combination with additive CTAC or PEG20000. These results were beneficial for understanding the mechanisms and facilitating the rational design of additives for metal nickel electrodeposition.

Highly efficient and selective membrane separation of copper from nickel in ammoniacal solution using mixtures of M5640 and BESO as membrane carriers

A FSSLM system developed with M5640/BESO as the synergistic carrier was used for selective separation of copper and nickel.

CoMoW / Al2O3-MgO-Li2O Catalytic formulations for DBT hydrodesulphurization

Low acidity catalytic formulations were prepared incorporating MgO and Li2O to the conventional CoMoW / Al2O3 catalysts. The CoMoW active phases were impregnates using an ammoniacal solution containing the metallic complexes as citrates. A high dispersion of the Co, Mo and W species in octahedral coordination, inhibiting the agglomeration towards phase like MoO3, WO3 and Co3O4, was attained. The obtained formulations preserve the catalytic activity in the hydrodesulphurization (HDS) reaction of dibenzothiphene (DBT), enhancing the selectivity towards the direct desulphurization route. The prepared formulations show a lower hydrogenation function due to its low acidity.

Preliminary investigations on hydrometallurgical treatment of spent Li-ion batteries

The paper reports investigations of the direct recovery of copper and cobalt from sulphate solution after leaching of spent Li-ion cells. Metals of high purity (above 99%) can be selectively obtained if the electrolysis process is carried out at proper pH: 1 for Cu and 4 for Co. During cobalt electrowinning, the oxidation of Co(II) ions and formation of Co(III) compounds on the anode were observed. Lithium ions accumulated mainly in the electrolyte. Application of ammoniacal solution for selective lithium carbonate precipitation in the presence of cobalt ions was not effective due to high temperature of the process and no possible formation of the stable and soluble cobalt-ammonia complexes.