The escalating production and use of lithium-ion batteries (LIBs) have led to a pressing need for efficient and sustainable methods for recycling valuable metals such as cobalt, nickel, manganese, and lithium from spent cathode materials. Traditional hydrometallurgical leaching approaches, based on mineral acids, face significant limitations, including high reagent consumption, secondary pollution, and poor selectivity. In recent years, deep eutectic solvents (DESs) and ionic liquids (ILs) have emerged as innovative, environmentally benign alternatives, offering tunable physicochemical properties, enhanced metal selectivity, and potential for reagent recycling. This review provides a comprehensive analysis of the current state and prospects of leaching LIB cathode materials using DES and ILs. We summarize the structural diversity and composition of common LIB cathodes, highlighting their implications for leaching strategies. The mechanisms, efficiency, and selectivity of metal dissolution in various DES- and IL-based systems are critically discussed, drawing on recent advances in both laboratory and real-sample studies. Special attention is given to the unique extraction mechanisms facilitated by complexation, acid–base, and redox interactions in DES and ILs, as well as to the effects of key operational parameters. A comparative analysis of DES- and IL-based leaching is presented, with discussion of their advantages, challenges, and industrial potential. While DES offers low toxicity, biodegradability, and cost-effectiveness, it may suffer from limited solubility or viscosity issues. Conversely, ILs provide remarkable tunability and metal selectivity but are often hampered by higher costs, viscosity, and environmental concerns. Finally, the review identifies critical bottlenecks in upscaling DES and IL leaching technologies, including long-term solvent stability, metal recovery purity, and economic viability. We also highlight research priorities that emphasize applying circular hydrometallurgy and life-cycle assessment to improve the sustainability of battery recycling.

The widespread use of activated carbon (AC) as an adsorbent in diverse applications generates substantial amounts of AC waste, posing environmental and disposal challenges. Therefore, effective AC regeneration is essential to enhance the sustainability of adsorption-based technologies. However, conventional regeneration methods often involve harsh chemicals or energy-intensive processes, limiting environmental and economic feasibility. In this study, the regeneration of commercial AC saturated with synthetic dyes Acid Blue 9 (AB9) and Acid Yellow 23 (AY23) is investigated using aqueous solutions of ionic liquids (ILs) as a green alternative. A set of ILs with varying cation–anion structures was synthesized and screened for regeneration performance, where [TBP][Sal] was identified as the most effective. Process parameters such as IL concentration, temperature, time, and solid-to-liquid ratio were optimized using response surface methodology, achieving regeneration efficiencies of up to 99% for AB9-AC and 80% for AY23. These efficiencies persisted over three cycles, while adsorption capacity remained unchanged for AY23 and decreased by ~40% for AB9. To improve sustainability, a preliminary study was conducted by implementing an aqueous biphasic system for IL and dye concentration from the post-regeneration solution. This integrated strategy presents a promising step toward the development of near-zero waste adsorption–regeneration cycles for AC adsorption applications.

The increasing demand for lithium-ion batteries (LIBs) and their limited lifespan emphasize the urgent need for sustainable recycling strategies. This study investigates the application of tetrabutylphosphonium-based ionic liquids (ILs) as alternative leaching agents for recovering critical metals, Li(I), Co(II), Ni(II), and Mn(II), from spent NMC cathode materials. Initial screening experiments evaluated the leaching efficiencies of nine tetrabutylphosphonium-based ILs for Co(II), Ni(II), Mn(II), and Li(I), revealing distinct metal dissolution behaviors. Three ILs containing HSO4−, EDTA2−, and DTPA3− anions exhibited the highest leaching performance and were selected for further optimization. Key leaching parameters, including IL and acid concentrations, temperature, time, and solid-to-liquid ratio, were systematically adjusted, achieving leaching efficiencies exceeding 90%. Among the tested systems, [TBP][HSO4] enabled near-complete metal dissolution (~100%) even at room temperature. Furthermore, an aqueous biphasic system (ABS) was investigated utilizing [TBP][HSO4] in combination with ammonium sulfate, enabling the complete extraction of all metals into the salt-rich phase while leaving the IL phase metal-free and potentially suitable for reuse, indicating the feasibility of integrating leaching and extraction into a continuous, interconnected process. This approach represents a promising step forward in LIB recycling, highlighting the potential for sustainable and efficient integration of leaching and extraction within established hydrometallurgical frameworks.

Pesticides used in agriculture can contaminate foods like fruits and vegetables, posing health risks to consumers and highlighting the need for effective residue monitoring. This study explores aqueous two-phase systems (ATPSs) comprising phosphonium or ammonium ionic liquids (ILs) combined with ammonium sulfate as an alternative pre-treatment method for extracting and concentrating the pesticides clomazone, pyraclostrobin, and deltamethrin from strawberry samples. Liquid–liquid equilibrium measurements for each ATPS were conducted, followed by extraction experiments to determine the most efficient systems for pesticide extraction. Results showed that all three pesticides migrated effectively to the IL-rich phase across the tested ATPSs. For the most promising system, tetrabutylphosphonium salicylate ([TBP][Sal]) with ammonium sulfate, extraction efficiencies for each pesticide exceeded 98% under optimized conditions for parameters such as pH, temperature, and ATPS composition. Application of this ATPS to strawberries resulted in significant pesticide preconcentration, reaching mg/L levels suitable for detection by liquid chromatography. The method’s sustainability was supported by green chemistry metrics, with AGREEprep and AGREE scores of 0.68 and 0.55, respectively, underscoring its alignment with eco-friendly practices.

Polyphenols are natural compounds with enhanced antioxidant properties. They are present in relatively high concentrations in fruit/vegetable by-products. Therefore, there is a need for the development of efficient and cost-effective methods for the separation and purification of these valuable compounds. Traditional extraction with organic solvents needs to be switched to novel methods that are more efficient, with reduced extraction times and low consumption of organic solvents. Aiming at developing sustainable processes for the separation and purification of phenolic compounds, we used three model compounds, namely resveratrol, quercetin, and gallic acid, to investigate ionic liquid-based aqueous biphasic systems (IL-ABSs) formed by cholinium-based IL in combination with polypropylene glycol with a molecular mass of 400 g/mol (PPG400). The ABS composition in the two-phase region was selected according to a previously determined phase diagram. Extraction studies indicated the preferential partition of resveratrol and quercetin toward the hydrophobic PPG-rich phase that is mainly dominated by its hydrophobic nature and the strong salting-out effect of ILs. On the other hand, due to its considerably hydrophilic nature, gallic acid preferentially migrates toward the IL phase. The achieved results from grape stem extract demonstrated high extraction efficiencies of cholinium dihydrogen phosphate (~99% for resveratrol for the PPG phase and 78% for gallic acid for the IL phase), with considerable selectivity, demonstrating promising outcomes for potential applications.

Sage has been used in traditional medicine to prevent and treat many health problems. This study aimed to determine and compare the phytochemical composition and antioxidative activity of sage leaf extracts obtained with 50% methanol (50MSE) and 80% methanol (80MSE). We determined the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) in extracts. Terpenoids were identified using gas chromatography-mass spectrometry (GC–MS), and the radical scavenging capacity of extracts was measured using DPPH assay. TPC was higher in 80MSE, TTC was higher in 50MSE, and TFC did not differ. GC–MS analysis showed that the content of α-thujone and L-camphor was low in both extracts, with higher content in 50MSE. DPPH assay indicated that a slightly lower IC50 value and higher antioxidant potential had 80MSE. Results pointed out that the polarity of the solvent and water content had different effects on the extraction of polyphenols and terpenoids.

This study investigates tetrabutylphosphonium-based ionic liquids for food dye removal via extraction using aqueous biphasic systems with ammonium sulfate. Furthermore, these ionic liquids were used for activated carbon regeneration and employed for dye removal from the water as well. This dual approach achieved high extraction efficiencies (≈ 90%) and nearly complete regeneration (98%) of the activated carbon used as a food dye adsorbent. These findings underscore the potential of tetrabutylphosphonium ionic liquids for managing dye-contaminated water.

The safety of drinking water is crucial for public health. Industrial and human activities have increased the use of heavy metals (cobalt, nickel, manganese) in water sources. These non-biodegradable, potentially carcinogenic metals pose serious health risks in drinking water. This study developed an efficient aqueous biphasic system (ABS) for removing these metals using real drinking water samples. Two ionic liquids, tetrabutylphosphonium DTPA ([TBP][DTPA]) and tetrabutylphosphonium acetate ([TBP][Ac]), were selected as ABS components, with ammonium sulfate as the salting-out agent. Phase diagrams were established, and extraction efficiencies were evaluated. The [TBP][DTPA] IL demonstrated superior performance, achieving over 95% extraction efficiency for all metals due to the stable complex formation with metal ions. The ABS proved highly effective for real samples, making it a promising approach for ensuring safe drinking water.

More environment-friendly solvents in analytical chemistry are almost inevitable in both sample preparation and analysis to meet the high standards of sustainable chemistry and human welfare. In this review paper, a critical look at the advantages and still unsolved problems of most potential classes of green solvents is presented to give an overview of the current state-of-the-art in this field. Replacing volatile organic compounds (VOCs) by ecofriendly and benign solvents in extractions/separations in sample preparation, as the most tedious and demanding step in analysis, is one of roads toward sustainable chemistry. Water under sub- and supercritical conditions, carbon-dioxide, ionic liquids (ILs), deep eutectic solvents (DESs), and those of natural origin (NADES) belong to the most promising classes of solvents in green analytical chemistry. Basic theory and mechanisms of their use illustrated by representative but not exhaustive list of examples related to complex matrices (environmental and natural food products) from analytical practice are presented in this review. Perspectives of QuEChERS, in line with GAC principles, are highlighted, in line with current trends of "going green" for quick, easy, cheap, effective, rugged, and safe analytical methods. Compliance with green chemistry (GC), especially green analytical chemistry (GAC) principles, is not a fashionable issue but, more the trend toward a sustainable future with greener chemistry; thus, green metrics are an unavoidable tool to measure how green the applied method or procedure is. Herein, the most common tools will be presented and discussed, such as national environmental method index (NEMI), analytical ecoscale, green analytical procedure index (GAPI), analytical greenness calculator (AGREE), complementary green analytical procedure index (ComplexGAPI), and analytical greenness metric for sample preparation (AGREEprep). The future trends for research and development in this still expanding field are presented in a critical view of advantages and disadvantages as well as improvement of the validation of analytical procedures. The creation of new certified reference materials (CRMs) and validated methods for specified analytes in complex matrices is a demanding task in the coming years. Tailor-made solvents with physicochemical properties for intended use are required for the selective extraction and separation and open numerous possibilities and huge potential for future research and industrial applications.