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.

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.

Four TiO₂ electrodes have been investigated for the oxygen reduction reaction (ORR) in 2 M NaOH. Anodic oxidation of Ti-foil was used as the final or the first step in the preparation of four electrodes based on TiO₂: amorphous (Ti/AM-TiO₂), two anatase forms (Ti/A400-TiO₂ and Ti/A550-TiO₂), and, finally, lithium-anatase form (Ti/A-Li_0.25TiO₂), all of them obtained as TiO₂ nanotube arrays. The electrodes’ structure was examined by Raman spectroscopy. Cyclic voltammetry and chronoamperometry were employed for the study of kinetics of ORR. Ti/A-Li_0.25TiO₂ and Ti/A400-TiO₂ electrodes showed the highest catalytic activity for ORR with the highest cathodic peak current density and the lowest Tafel slope values. Number of electrons exchanged during ORR at TiO₂ electrodes was in the range from 2.3 to 2.8. Additionally, TiO₂ electrodes showed good stability as well as acceptable selectivity in the presence of borohydride, methanol or ethanol as typical fuels for fuel cells. Thus this study introduces a simple, low-cost preparation route of TiO₂-based electrodes with high efficiency for ORR for energy conversion and storage applications.

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.