Ewa Rudnik

Bio: Ewa Rudnik is an academic researcher from AGH University of Science and Technology. The author has contributed to research in topics: Chloride & Nickel. The author has an hindex of 17, co-authored 85 publications receiving 795 citations.

Hydrometallurgical recovery of cadmium and nickel from spent Ni-Cd batteries

Abstract: The paper is concerned with a simple hydrometallurgical method for the selective recovery of cadmium and nickel from spent Ni–Cd batteries. The following consecutive stages are proposed: dismantling, leaching in sulphuric acid, cadmium electrowinning, Fe3+ removal and nickel electrowinning. The influence of H2O2 addition to the leaching solution on the efficiency of the dissolution process was investigated. The electrowinning of cadmium was carried out at various pH and current densities (100 and 400 A/m2). Fe3+ ions were removed from the bath by hydroxide precipitation. Nickel electrolyses were conducted at pH of 9 and two current densities (100 and 400 A/m2). Concentrations of Ni2+, Cd2+ and Fe3+ ions as well as cathode potentials and electrolysis voltages were monitored during the electrowinning. Efficiencies of leaching and electrolysis were calculated. Final products were metals of high purity (98–100% Cd, 98–99% Ni). Maximum total recoveries of cadmium and nickel from spent Ni–Cd batteries were 92% and 67%, respectively. A preliminary assessment of an economic viability of the proposed treatment was undertaken.

Electrodeposition of nickel/SiC composites in the presence of cetyltrimethylammonium bromide

Abstract: Electrodeposition of SiC particles with nickel matrix in the presence of cetyltrimethylammonium bromide (CTAB) at two current densities was carried out. Surface chemistry (amount of acidic and basic superficial groups, surface charge, Ni2+ and Br− adsorption) of the SiC powder in the presence of various CTAB amounts (0–1.1 mM) was studied. Cationic surfactant inhibited adsorption of cations and enhanced adsorption of anions on the positive charged carbide surface, but Br−/Ni2+ molar ratios for adsorbed ions were higher than in the bath. It was attributed to the CTAB adsorption realized predominantly by hydrophobic interactions between aliphatic chain of the molecule and SiC surface with the positive head group of CTA+ pointed toward the bulk solution. Increased SiC incorporation to the composite coating with CTAB addition was observed. Correlation between current efficiency and Br−/Ni2+ molar ratios for ions adsorbed on SiC was found. The influence of CTAB concentration on the cathodic polarization curves was also determined. Structure of the composite coatings was studied by microscopic observations. Microhardness of the fine-grained metal matrix composites was also determined.

Electrodeposition and heat treatment of nickel/silicon carbide composites

Abstract: Electrodeposited Ni/SiC composite coatings were obtained in a Watts-type bath. The effect of fine SiC particles on polarization curves of the cathodic reduction of nickel ions was discussed. The incorporation of the particles into the deposit with respect to current density and SiC concentration in the bath was tested. Cathodic current efficiencies were also calculated. Structure of as-plated and heat-treated Ni/SiC composites were examined by means of metallography observations as well as scanning and transmission electron microscopy methods. Two phase transformations in the temperatures range of 20–700 °C were found. For annealed samples, Ni 2 Si and Ni 3 Si 2 phases were identified. Hardening of the Ni/SiC composites as a function of the particle content in the deposit and annealing temperature was determined by means of the microhardness testing method.

The influence of electrolysis parameters on the composition and morphology of Co–Ni alloys

Abstract: The influence of cathodic current density, the concentration of Co 2+ ions in the electrolyte, and additional substances (saccharin and sodium lauryl sulfate) on the composition and morphology of Co–Ni alloys were investigated. Research was carried out in a Watts-type bath in the presence of boric acid, as a buffer substance. The circulation speed of the electrolyte was 40 dm 3 h −1 . Cathodic polarisation curves were determined for parent metals and the Co–Ni alloy. It was established that the presence of additives shifts the cathodic potential of alloy deposition towards more negative values. An increase in the cobalt content in the alloy was observed with decreasing of the cathodic current density and increasing of the Co 2+ ions concentration in the bath. Results obtained confirmed the anomalous character of deposition of the Co–Ni alloy. The cathodic current efficiency is dependent mainly on the current density applied, but the direction of changes has not been precisely determined, for it depends on the composition of the electrolyte. Using diffractional X-ray and micro X-ray analyses, it was determined that single-phase deposits with an fcc lattice for the whole investigated range of current density and electrolyte composition were obtained. In the presence of additives there were obtained fine-grained, bright alloys which adhered well to the substrate.

Hydrometallurgical recovery of copper and cobalt from reduction-roasted copper converter slag

Abstract: The paper is concerned with a simple hydrometallurgical method for selective recovery of copper and cobalt from industrial copper converter slag. The following consecutive stages are proposed: roasting of the slag in reduction conditions to produce Cu–Co–Fe–Pb alloy, electrolytic dissolution of the alloy in an ammonia–ammonium chloride solution, ammoniacal leaching of the slime, selective copper and cobalt electrowinning. Cu27–Co6–Fe64–Pb1.5 alloy was a five-phase system and did not dissolve uniformly during electrolysis. This resulted in the separation of the metals, wherein iron remained in the slime, while copper and cobalt were components of slime, electrolyte and cathodic deposit. A mechanism of the alloy dissolution was developed. A series of secondary processes took place in the system: precipitation of iron compounds, copper cementation with cobalt and iron; adsorption of copper and cobalt ions on the iron precipitates. Final products were metals of high purity (99.9% Cu, 92% Co).

Toward sustainable and systematic recycling of spent rechargeable batteries

Abstract: Ever-growing global energy needs and environmental damage have motivated the pursuit of sustainable energy sources and storage technologies. As attractive energy storage technologies to integrate renewable resources and electric transportation, rechargeable batteries, including lead–acid, nickel–metal hydride, nickel–cadmium, and lithium-ion batteries, are undergoing unprecedented rapid development. However, the intrinsic toxicity of rechargeable batteries arising from their use of toxic materials is potentially environmentally hazardous. Additionally, the massive production of batteries consumes numerous resources, some of which are scarce. It is therefore essential to consider battery recycling when developing battery systems. Here, we provide a systematic overview of rechargeable battery recycling from a sustainable perspective. We present state-of-the-art fundamental research and industrial technologies related to battery recycling, with a special focus on lithium-ion battery recycling. We introduce the concept of sustainability through a discussion of the life-cycle assessment of battery recycling. Considering the forecasted trend of a massive number of retired power batteries from the forecasted surge in electric vehicles, their repurposing and reuse are considered from economic, technical, environmental, and market perspectives. New opportunities, challenges, and future prospects for battery recycling are then summarized. A reinterpreted 3R strategy entailing redesign, reuse, and recycling is recommended for the future development of battery recycling.

Synthesis, Characterization, and Properties of Metal Phosphide Catalysts for the Hydrogen-Evolution Reaction

Abstract: Hydrogen gas obtained by the electrolysis of water has long been proposed as a clean and sustainable alternative to fossil fuels. Noble metals such as Pt are capable of splitting water at low overpotentials, but the implementation of inexpensive solar-driven water-splitting systems and electrolyzers could benefit from the development of robust, efficient, and abundant alternatives to noble metal catalysts. Transition metal phosphides (MxPy) have recently been identified as a promising family of Earth abundant electrocatalysts for the hydrogen-evolution reaction (HER) and are capable of operating with low overpotentials at operationally relevant current densities while exhibiting stability under strongly acidic conditions. In this review, we highlight the progress that has been made in this field and provide insights into the synthesis, characterization, and electrochemical behavior of transition metal phosphides as HER electrocatalysts. We also discuss strategies for the incorporation of metal phosphides ...

Hydrometallurgical Processes for Recycling Spent Lithium-Ion Batteries: A Critical Review

Abstract: The amount of spent lithium-ion batteries has grown dramatically in recent years, and the development of a recycling process for spent lithium-ion batteries is necessary and urgent from the viewpoi...

A review of the electrodeposition of metal matrix composite coatings by inclusion of particles in a metal layer: an established and diversifying technology

Abstract: Following a brief overview of their history, which dates back to the 1920s with marked developments during the 1960s and 1970s, the principles of composite coatings, achieved by including particles dispersed in a bath into a growing electrodeposited metal layer, are considered. The principles and role of electroplating compared to other techniques for realising such coatings, are considered. A good quality particle dispersion (often aided by a suitable type and concentration of surfactants) appropriate choice of work-piece shape/geometry and controlled agitation in the bath are seen to be prerequisites for achieving uniform coatings having a well-dispersed particle content by electroplating. Examples are provided to illustrate the influence of bath composition and plating conditions on deposit properties. Engineering applications of included particle composite layers are illustrated by examples of hard ceramic, soft ceramic and polymer inclusion composite coatings from the recent literature. Current trends in the development of composite plated coatings are summarised and their diverse applications are seen to include the use of finely structured (especially nanostructured) and functionally active particles together with hybrid and more complex, e.g. hierarchical, structures for applications ranging from tribology to speciality electronics, magnetic and electrochemical energy conversion materials.