In this study, an ultrasonic assisted natural deep eutectic solvent (DES) was used to extract hydroxytyrosol (HT) from olive leaves. The optimal extraction conditions of the MaPa-4 concentration, extraction time and solid–liquid ratio were obtained by single factor experiments. The formation mechanism of MaPa and its interaction with HT were analyzed by FTIR, ¹H-NMR and density functional theory (DFT) calculation. Then, MaPa-4 and water extracts obtained under the optimal extraction conditions were selected for a series of efficacy tests. MaPa-4 extract demonstrated low cytotoxicity, good biocompatibility, and excellent anti-inflammatory and bacteriostatic properties. Overall, MaPa-4, as an environmentally friendly and efficient solvent, was combined with ultrasound treatment to develop an efficient, green and feasible method to extract HT from olive leaves.

Direct regeneration is a low-cost and environmentally friendly way of recycling spent Li-ion batteries. In this study, a new method is adopted to regenerate spent LiFePO₄. First, the spent LiFePO₄ powder is homogenized, and then, small amounts of a lithium source and a carbon source are thoroughly mixed by spray drying. After that, a high-temperature solid-phase method is used to regenerate the carbon-coated lithium iron phosphate. Compared with traditional regeneration methods, the proposed method significantly improves the universality of spent LiFePO₄ having different degrees of damage. The regenerated LiFePO₄ is characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and electrochemical measurements. The results show that the regenerated sample has a stable morphology, structure, and electrochemical performance. Under the conditions of 0.1C, the initial capacity exceeds 160 mA h g⁻¹. After 800 cycles under the conditions of 1C, the capacity retention is 80%, which satisfies the requirements for regenerated LiFePO₄ batteries.