Ewa Rudnik

The influence of phase structure on the dissolution of Cu–Co–Fe alloys in sulphuric acid solution and the metals recovery

Abstract Investigations of Cu–Co–Fe alloys dissolution in sulphuric acid solution were conducted. The phase compositions were identified before electrochemical experiments. Anodic dissolution was found to give about 100% current efficiency and was independent of anode composition. Passivation of anodes was not observed. Dissolution was selective; iron and cobalt were transferred into the electrolyte, while copper was left in anodic slimes and/or deposited on the cathode.

Comparative studies on hydrometallurgical treatment of smelted low-grade electronic scraps for selective copper recovery

Abstract A comparison of three hydrometallurgical methods for selective recovery of copper from low-grade electric and electronic wastes was reported. Scraps were smelted to produce Cu–Zn–Sn–Ag alloy. Multiphase material was analyzed by SEM–EDS and XRD. The alloy was dissolved anodically with simultaneous metal electrodeposition using ammoniacal and sulfuric acid solutions or leached in ammonia–ammonium sulfate solution and then copper electrowinning was carried out. This resulted in the separation of metals, where lead, silver and tin accumulated mainly in the slimes, while copper was transferred to the electrolyte and then recovered on the cathode. The best conditions of the alloy treatment were obtained in the sulfuric acid, where the final product was metal of high purity (99% Cu) at the current efficiency of 90%. Ammoniacal leaching of the alloy led to the accumulation of copper ions in the electrolyte and further metal electrowinning, but the rate of the spontaneous dissolution was low. Anodic dissolution of the alloy in the ammonia–ammonium sulfate solution led to the unfavorable distribution of metals among the slime, electrolyte and cathodic deposit.

Effect of anions on the electrodeposition of tin from acidic gluconate baths

Electrodeposition of tin from acidic gluconate baths (chloride, chloride–sulfate) was investigated. Equilibrium distribution of tin(II) species in both solutions was calculated. Cyclic voltammetric, potentiostatic, and galvanostatic measurements showed that cathodic process can run under limiting current due to the presence of tin complex electroactive species. Average effective diffusion coefficients of metal species were determined. Nucleation of tin occurred through a progressive three-dimensional diffusion growth model. A characteristic of tin deposits was also presented.

Incorporation of Ceramic Particles into Nickel and Cobalt Electroless Deposits

Abstract- The aim of this work was to elucidate factors affecting electroless codeposition of metals with ceramic particles. Codeposition of SiC, SiO 2 and Al 2 O 3 particles with Ni-P and Co-P matrixes in citrate-malonate alkaline solutions was compared. The positive surface charge of SiC particles corresponded to increased adsorption of hypophosphite anions, while negatively charged SiO 2 and Al 2 O 3 particles showed high adsorption of metal ions. It resulted in high incorporation of the carbide into the metal layers and low percentages of oxides in the coatings. Adsorption of nickel ions on SiC particles was promoted by the presence of maleic acid in the bath, however it did not improve incorporation of the particles into the Ni-P matrix. Equilibrium distribution of the species in the plating baths was also calculated. Keywords- Electroless Deposition; Nickel; Cobalt; Composite; Surface Charge; Adsorption I. INTRODUCTION Composite coatings are produced usually by incorporation of solid particles into a metallic matrix in electrolytic or electroless processes

Kinetic Studies of Gold Recovery from Diluted Chloride Aqueous Solutions Using Activated Carbon Organosorb 10 CO

The kinetic studies of gold(iii) chloride complex ions recovery from acidic solution using activated carbon (AC) were carried out using spectrophotometry. AC samples were characterized in terms of surface area, porosity, and zeta potential. The surface functional groups were also identified. It was found that adsorption of AuCl4– onto AC was followed by reduction of the ions to the metallic form. The process obeyed the first order reaction model, but the reaction was controlled by diffusion. Arrhenius and Eyring–Polanyi equations were used for determination of the activation parameters. Distribution of gold across the AC pellets was also determined and discussed according to the porous material theory.

The influence of current density and bath composition on the electrodeposition of nickel and nickel/silicon carbide composite

SUMMARY Electrodeposited nickel and nickel/silicon carbide composite coatings were obtained in a Watts-type bath. The influence of organic additives and current density on the microstructure and the grains size of the deposits was studied and the relationship between the nickel microstructure and the internal stress of deposits evaluated.

Studies on the Codeposition of SiC Nanopowder with Nickel, Cobalt, and Co-Ni Alloys

Electrodeposition of SiC nanopowder (approximately 120 nm) with nickel, cobalt, and Co-Ni alloy matrix was studied. It was found that particles suspended in the bath affect slightly the reduction of metallic ions. Incorporation of the ceramic particles was governed mainly by the morphology of the matrix surface, while no strict correlation between the amount of cobalt ions adsorbed on the powder and the SiC content in the composites was found. Microhardness of nickel deposits was HV, while for cobalt-rich coatings (84–95 wt.% Co) the values were in the range of 260–290 HV, independently of the SiC content in the coatings. Fine-grained nickel deposits were characterized by good corrosion resistance, while cobalt and Co-Ni alloys showed high corrosion current densities.

Electro- and Electroless Deposition of Ni/SiC and Co/SiC Composite Coatings on Aluminum

Aluminum and its alloys characterize usually poor superficial properties. To improve hardness and wear resistance, aluminum base materials are covered by protective layers. Deposition of metallic coatings on aluminum is accompanied by some difficulties due to tenacious oxide layer present on the substrate surface. Hence, some additional stages are needed to assure good adhesion of the coating to the substrate. In many cases, electrodeposition and electroless methods are competitive for providing deposits with ceramic particles uniformly incorporated within the metal layer. The most extensive studies were carried out on deposition of Ni/SiC composites, but no attempts on Co/SiC coatings deposition on aluminum have been performed. Experiments presented were conducted to develop simply methods for deposition of Ni/SiC and Co/SiC composite coatings on aluminum substrate. The consecutive stages of the hydrometallurgical route were: zincating of aluminum in alkaline solutions, electroless nickel (cobalt) deposition and electrodeposition or electroless deposition of the composite coating. The influence of deposition time and composition of the baths on thickness and composition of the deposits was studied. Microstructure and microhardness of as-plated individual layers were also determined.

A brief review on bio-inspired superhydrophobic electrodeposited nickel coatings

ABSTRACT Superhydrophobic electroplated metallic layers are a relatively novel type of functional coatings. They are interesting not only from the scientific point of view, but also from a wide range of potential practical applications, e.g. for anticorrosion protection. Commercialisation of the laboratory work requires deeper understanding of the principles of production and specific surface properties, such as morphology, roughness, surface chemistry, surface wetting and long-term stability of the material. This paper presents a brief review focused on current knowledge of superhydrophobic nickel coatings, modes of their fabrication and characterisation, since technical electroplated nickel belongs to the most important engineering materials in modern technology.

Platinum(iv) Chloride Complex Ions Adsorption on Activated Carbon Organosorb 10CO

Kinetic studies on the recovery of platinum(iv) chloride complex ions from acidic solutions using commercially available activated carbon (AC) were carried out using spectrophotometric methods. The overall process obeyed first-order reaction model. The overall process is complex and consists of two steps: the first one is related to the reversible adsorption–desorption of PtIV complex and the second one is related to the reduction of PtIV complex on the AC surface. The first step of the overall process was limited by diffusion, whereas the second step ran under kinetic control. The activation energies of the individual reactions in both steps were determined and corresponded to 18.27, 7.85, and 31.2 kJ mol–1 for the adsorption, desorption, and reduction reactions, respectively. X-ray photoelectron spectroscopy results confirmed that the chemical reaction was related to the reduction of PtIV to PtII on the AC surface. The results show that the investigated AC can be applied for platinum recovery from highly diluted aqueous systems.