Search Results (14)

Platinum group metals (PGMs), platinum (Pt), palladium (Pd) and rhodium (Rh), are critical for automotive emission control, chemical manufacturing and emerging energy technologies, yet their supply is limited and geographically concentrated. Their designation as critical raw materials (CRMs) in the EU has intensified recycling efforts, especially from spent automotive catalysts. Conventional pyrometallurgical and acid-based hydrometallurgical routes achieve high recovery efficiencies but rely on aggressive reagents and energy-intensive processing. Deep eutectic solvents (DESs) have emerged as greener leaching media capable of dissolving PGMs under milder and tunable conditions. This review outlines the conventional hydrometallurgical framework, summarizes DES fundamentals relevant to metals dissolution, and critically assesses recent advances in DES-based leaching of PGMs from spent catalysts. The influence of solvent composition, oxidants and complexing ligands on PGMs speciation and recovery is discussed, together with emerging reporting guidelines and research priorities. Overall, DES-based leaching offers a promising and potentially safer route for autocatalyst recycling but the technology remains at an early stage of development, requiring further mechanistic insight and sustainability evaluation. Full article

Antimony (Sb) is a key element used in flame retardants, lead–acid batteries, and polymer catalysis, and it is classified as a critical raw material. Its quantity for the worldwide economy is limited due to restricted natural resources and partial recycling of by-products. This is why recovering Sb from secondary sources is becoming increasingly important in terms of technological and economic aspects for ensuring its sustainable and safety supply. In this paper, we review the possibilities for extraction of antimony from various waste sources, such as ore processing and metal recovery residues, electronic and plastic waste, lead-antimony-containing waste, spent catalysts, fluorescent lamps, incinerated municipal waste, and the applied methods of waste processing (pyrometallurgy, hydrometallurgy, solvometallurgy) used to achieve recovery in high yield and purity. The methods for antimony quantification and speciation are also discussed and described in terms of principle of the technique, linear concentration range, limit of detection, and coupling with other techniques. As the concentration of Sb in environmental and biological samples is usually very low and requires good selectivity and sensitivity of the analytical method, suitable techniques for sample preparation and subsequent instrumental measurement are also included. Full article

Samarium, a rare earth element, is crucial for advanced technological applications, particularly due to the exceptional magnetic properties of Sm_xCo_y intermetallics, discovered over 50 years ago. However, its growing significance and demand have highlighted concerns about scarce, commercially viable natural sources and the complex separation processes needed to isolate it from other lanthanides. In this context, electrodeposition has emerged as a versatile method for both synthesizing samarium materials and recovering the element. A major obstacle in applying electrolysis lies in the complex electrochemical behavior of samarium species, stemming from their highly negative electrochemical potential. While this limits the use of aqueous solutions, it also opens up possibilities for alternative solvents, such as molecular liquids, ionic liquids, deep eutectic solvents, and molten salts. The electrochemical properties of samarium have prompted exploration into electrodeposition techniques for material synthesis and recycling. This review discusses various aqueous and non-aqueous electrolyte compositions, different electrolysis modes, and the role of cathode substrates. It also shows the potential of electrolysis in the fabrication of various cathode products (metal, alloys/intermetallics, inorganic compounds), highlighting both challenges and opportunities in its practical implementation. Full article

Lithium-ion batteries (LiBs) are utilized in numerous applications due to advancements in technology, and the recovery of end-of-life (EoL) LiBs is imperative for environmental and economic reasons. Pyrometallurgical and hydrometallurgical methods have been used in the recovery of metals such as Li, Co, and Ni in the EoL LiBs. Hydrometallurgical methods, which have been demonstrated to exhibit higher recovery efficiency and reduced energy consumption, have garnered increased attention in recent research. Inorganic acids, including HCl, HNO₃, and H₂SO₄, as well as organic acids such as acetic acid and citric acid, are employed in the hydrometallurgical recovery of these metals. It is imperative to acknowledge the environmental hazards posed by these acids. Consequently, solvometallurgical processes, which involve the use of organic solvents with minimal or no water, are gaining increasing attention as alternative or complementary techniques to conventional hydrometallurgical processes. In the context of solvent systems that have been examined for a range of solvometallurgical methods, deep eutectic solvents (DESs) have garnered particular interest due to their low toxicity, biodegradable nature, tunable properties, and efficient metal recovery potential. In this study, the leaching process of black mass containing graphite, LCO, NMC, and LMO was carried out in a short time using the ternary DES system. The ternary DES system consists of choline chloride (ChCl), glycolic acid (GLY), and ascorbic acid (AA). As a result of the leaching process of cathode powders in the black mass without any pre-enrichment process, Li, Co, Ni, and Mn elements passed into solution with an efficiency of over 95% at 60 °C and within 1 h. Moreover, the kinetics of the leaching process was investigated, and Density Functional Theory (DFT) calculations were used to explain the leaching mechanism. Full article

The rapid growth in lithium-ion battery (LIB) demand has underscored the urgent need for sustainable recycling methods to recover critical metals such as lithium, cobalt, nickel, and manganese. Traditional pyrometallurgical and hydrometallurgical approaches often suffer from high energy consumption, environmental impact, and limited metal selectivity. As an emerging alternative, solvometallurgy, and in particular the use of low-melting mixtures solvents, including deep eutectic solvents, offers a low-temperature, tunable, and potentially more environmentally compatible pathway for black mass processing. This review presents a comprehensive assessment of the recent advances (2020–2025) in the application of LoMMSs for metal recovery from LCO and NCM cathodes, analyzing 71 reported systems across binary, ternary, hydrated, and non-ChCl-based solvent families. Extraction efficiencies, reaction kinetics, coordination mechanisms, and solvent recyclability are critically evaluated, highlighting how solvent structure influences performance and selectivity. Particular attention is given to the challenges of lithium recovery, solvent degradation, and environmental trade-offs such as energy usage, waste generation, and chemical stability. A comparative synthesis identifies the most promising systems based on their mechanistic behavior and industrial relevance. The future outlook emphasizes the need for greener formulations, enhanced lithium selectivity, and life-cycle integration to support circular economy goals in battery recycling. Full article

It has been demonstrated that the traditional hydrometallurgical method is still economically viable in several industrial applications such as Bayer, Boix, Platsol, Sherrit-Gordon, and so on. The conventional extraction technique of valuable metals from their ores using an aqua medium has several challenges. The following can be listed for the illustration of this: (1) Inorganic acids used during the leaching process have been proven to be non-environmentally friendly and ready to lead to non-selective processes in general, except in rare cases used in alkaline environments. (2) Special linings are required in the reactors used due to the corrosive impact of acids such as HCl and H₂SO_4, especially when leaching at high temperatures, rendering all processes costly. (3) Practically, using inorganic acids while leaching samples containing amorphous silicate phases leads to gel formation. Solvometallurgy overcomes these challenges by substituting the aqueous phase for other polar solvents, such as polar molecular organic or ionic solvents. The advantage of this substitution lies in the ability to manipulate metal ion distribution using solvents with varying solvation properties. This review examines the potential of solvometallurgical processes (solvoleaching) over conventional hydrometallurgy as viable alternatives for metal extraction from sulfide ores. It highlights the key distinctions between hydrometallurgy and solvometallurgy while emphasizing the potential economic and environmental advantages solvometallurgy offers. Full article

Electronic waste (e-waste) is becoming a serious problem that impacts the environment due to its fast-growing volume. This rise is linked to high electronic and electrical equipment production to meet the increasing demand for high-end electronic devices. Conventional e-waste recycling approaches, including hydrometallurgy and pyrometallurgy, often involve substantial water and energy consumption and the generation of by-products, such as the emission of toxic gases or hazardous effluents. Within this context, solvometallurgy has emerged as a compelling alternative, whereby green non-toxic non-aqueous solvents, namely deep eutectic solvents (DESs), are used to extract and recover the metals with minimal water and harsh acid/base chemical use. The current study presents the solvo-leaching results of critical and strategic metals, i.e., copper (Cu) and nickel (Ni), and precious metals, i.e., gold (Au), from waste printed circuit boards (PCBs). Five different DESs were tested at mild conditions, namely at a temperature of 65 °C, a stirring speed of 300 rpm, a solid/liquid ratio of 10 g/L, and in the presence of iodine (I₂) for 96 h. Among the different solvents tested, the one consisting of choline chloride (ChCl), acetic acid (AA), and I₂ emerged as the optimal solvent, leading to the selective extraction of 99% of Cu, 92% of Ni, and 90% of Au from the PCB powder. Full article

The importance of rare earth elements as a basis for the development of new technologies or the improvement of existing ones makes their recovery from raw and waste materials necessary. In this recovery, hydrometallurgy and its derivative solvometallurgy play key roles due to their operational characteristics, which are emphasized with the use of ionic liquids. This manuscript reviews the most recent advances (2023 and 2024) in the use of ionic liquids in unit operations (leaching and separation technologies) aimed at the recovery of these valuable and strategic metals. Moreover, a comprehensive review is presented of the use of these chemicals in the development of advanced materials containing some of these rare earth elements. Full article

The boosted interest in using rare earth elements (REEs) in modern technologies has also increased the necessity of their recovery from various sources, including raw materials and wastes. Though hydrometallurgy plays a key role in these recovery processes, some drawbacks (apparent or not) of these processes (including the use of aggressive mineral acids, harmful extractants, and diluents, etc.) have led to the development of an environmental friendship subclass named solvometallurgy, in which non-aqueous solvents substituted to the aqueous media of the hydrometallurgical processing. Together with ionic liquids (ILs), the non-aqueous solvents chosen for these usages are the chemicals known as deep eutectic solvents (DEEs). The utilization of DEEs included the leaching of REEs from the different sources containing them and also in the separation-purification steps necessary for yielding these elements, normally oxides or salts, in the most purified form. This work reviewed the most recent literature (2023 year) about using deep eutectic solvents to recover REEs from various sources and coupling these two (DESs and REEs) to derive compounds to be used in other fields. Full article

This paper focuses on the environmental leaching of antimony, a critical mineral, using deep eutectic solvents. Mining residues often contain embedded antimony, posing environmental risks. Deep eutectic solvents, known for being low in toxicity, cost-effective, and environmentally friendly, present a promising avenue for sustainable antimony extraction. The study focuses on optimizing the leaching process through experimental analysis by considering variables such as temperature, time, and percentage of solids. Different deep eutectic solvent (DES) compositions are being studied, including choline chloride with malonic acid, thiourea, and ethylene glycol in different molar ratios, to identify the most effective solvent system for antimony extraction. A sample, originally obtained from mining waste produced via the flotation of antimonite ore, was used to test these three types of DESs. By optimizing the leaching process by changing the ratio of solid and liquid components, as well as the amount of oxidizing agent up to 3 g, iodine, yields of up to 100% were achieved after leaching for 4 h at 100 °C. The aim of the study is to advance sustainable resource management by providing knowledge on an ecological and feasible method of extracting antimony from mine waste, leading to more conscious and efficient resource practices in the mining sector. Full article

With the development of smart technologies, the use of rare-earth elements (REEs) has been widespread; thus, their importance as valuable and strategic metals has been boosted to levels never known before. Due to their scarcity in the Earth’s crust, the recovery of these elements from secondary resources has also witnessed further developments. Traditional pyrometallurgical and hydrometallurgical processing techniques, though widely used in the recovery of these REEs, have some environmental drawbacks; thus, new recovery approaches are under development. Here, Solvometallurgy has emerged as an environmentally friendly technology, and ionic liquids and deep eutectic solvents have turned out to be first-line chemicals to be used in the different unit operations employed in solvometallurgical processing, i.e., leaching, liquid–liquid extraction, ion exchange (adsorption), precipitation, and electrolysis. This manuscript reviews the most recent literature (2002–June 2023) concerning the use of ionic liquids and deep eutectic solvents in the recovery of REEs from various sources. Full article

The strategic importance of platinum and palladium, two platinum-group metals (PGMs), is particularly supported by their technological applications, one of the most relevant being the role they perform as catalysts for several sorts of chemical reactions. The cumulative demand for these two PGMs to be used as catalysts more than justifies increasing research efforts to develop sustainable recycling processes to maintain their supply. This critically appraised topic review describes the recent research trends (since 2010) developed by the world’s research communities to reach sustainable methods to recover platinum and palladium from spent catalysts in the liquid phase, namely those involving a solvent extraction (SX) step. The selected recycling processes are based on extensive fundamental research, but this paper intends to focus on information collected about SX procedures applied to real leaching samples of spent catalysts, either from automobile or industrial sources. A critical appraisal of the claimed success levels, the identified constraints, and open challenges is carried out, together with some perspectives on possible ways to redirect research efforts and minimize the gap between academia and industry on this matter. Full article

The development of a truly circular economy necessitates the recovery and recycling of resources from secondary streams. In this work, we studied the extraction of metals from printed circuit boards (PCBs) using choline chloride: ethylene glycol deep eutectic solvents: Cu, Ni, Zn, and Sn were selectively extracted from the PCBs, with >75% extraction after 72 h for Cu, Ni, and Sn, and circa. 45% extraction for Zn. This solvometallurgical approach promises to minimize the use of water and acid/base reagents in processing. The results show a considerable ability to compete with current methods of metal extraction and therefore generate a strong potential to attain the goal of a sustainable circular economy via zero-waste green urban mining. Full article

In this work, the aqueous phase diagram for the mixture of the hydrophilic tributyltetradecyl phosphonium ([P₄₄₄₁₄]Cl) ionic liquid with acetic acid (CH₃COOH) is determined, and the temperature dependency of the biphasic region established. Molecular dynamic simulations of the [P₄₄₄₁₄]Cl + CH₃COOH + H₂O system indicate that the occurrence of a closed “type 0” biphasic regime is due to a “washing-out” phenomenon upon addition of water, resulting in solvophobic segregation of the [P₄₄₄₁₄]Cl. The solubility of various metal oxides in the anhydrous [P₄₄₄₁₄]Cl + CH₃COOH system was determined, with the system presenting a good selectivity for CoO. Integration of the separation step was demonstrated through the addition of water, yielding a biphasic regime. Finally, the [P₄₄₄₁₄]Cl + CH₃COOH system was applied to the treatment of real waste, NiMH battery black mass, being shown that it allows an efficient separation of Co(II) from Ni(II), Fe(III) and the lanthanides in a single leaching and separation step. Full article