Separations

Paracetamol (PAR) and orphenadrine citrate (ORPH) are two active substances commonly used in combination medicinal products, due to the analgesic effect of paracetamol and the muscle relaxant effect of orphenadrine, with a therapeutic indication of mild to moderate acute musculoskeletal pain. The aim of this work is to develop and validate an isocratic HPLC method for the simultaneous determination of PAR and ORPH in tablet formulation. Preliminary experiments showed that an analytical column with a chemically bound phenyl phase was required. A Box–Behnken design (BBD) was utilized to optimize the analytical method for two key responses, PAR asymmetry factor (Asym_PAR) and ORPH capacity factor (k_ORPH), with three numerical factors: percentage of ACN in mobile phase (A); pH (B); and salt concentration in the aqueous solution (C). The optimized method consists of a Pinnacle DB Biphenyl (250 × 4.6 mm) 5 µm column, and a mobile phase of 37%/63% v/v ACN-NaH₂PO4·H₂O in 29 mM aqueous solution, pH = 2.5. The flow rate was set to 1.5 mL/min and detection occurred at 215 nm. After the optimization process the following chromatographic conditions were selected and the method was validated for various ICH parameters covering system suitability, specificity, linearity (R² = 1.00), precision (%RSD ≤ 2), accuracy (98% ≤ %Recovery ≤ 102%), and robustness. Finally, the environmental friendliness of the novel method was assessed by using the Analytical GREEnness (AGREE) metric tool, obtaining a score of 0.67.

To develop low-cost and renewable materials for treating dye wastewater, an efficient biosorbent was prepared from Bambusa emeiensis bamboo powders (BPs) via a simple alkali pretreatment. Systematic investigation revealed that NaOH concentration was critical for enhancing adsorption performance. Under optimal conditions (NaOH ≥ 0.2 mol/L, dosage = 10.0 g/L), the BPs achieved over 96% removal of cationic Methylene Blue (MB, 20 mg/L) within 20 min, demonstrating rapid kinetics. The adsorption process followed the Langmuir isotherm model with a maximum adsorption capacity of 4.1 mg/g without adjusting the pH of the solution and complied with the pseudo-second-order kinetic model. Thermodynamic analysis confirmed the spontaneous (ΔG < 0) and exothermic (ΔH = −52.73 kJ/mol) nature of the adsorption. Notably, the alkali-treated BPs exhibited a pronounced preference for the cationic dye, achieving a high removal rate of 96.5% for MB, in contrast to a much lower removal of 23.6% for the anionic dye AO7 under identical single-dye conditions, attributed to the enhanced surface negative charge after alkali treatment. Furthermore, the BPs maintained a high removal efficiency of 91.2% after eight adsorption-desorption cycles using 0.1 mol/L HCl as eluent, demonstrating excellent reusability. This study presents a feasible and sustainable strategy for designing regenerative bamboo-based biosorbents with rapid and preferential adsorption capabilities for cationic dye wastewater.

With the rapid expansion of the global lithium battery industry, the demand for lithium as a critical raw material continues to grow. Lithium precipitation mother liquor still contains considerable concentrations of lithium ions (Li⁺), but they generally exhibit a high sodium-to-lithium ratio, which makes the separation of lithium from sodium particularly challenging. Solvent extraction is recognized as a viable approach for challenging Li⁺/Na⁺ separation due to its high selectivity, operational flexibility, and scalability. A comprehensive assessment and comparison of various extraction systems are therefore essential to facilitate the sustainable recovery of lithium from precipitation mother liquor. This review summarizes the commonly used extraction systems, including organophosphorus extractants, ketone-based extractants, macrocyclic compounds, ionic liquids, and deep eutectic solvents. A systematic analysis is provided regarding their extraction mechanisms, applicable conditions, and respective advantages and disadvantages. Finally, perspectives and suggestions are offered on future research directions and improvement strategies for different extraction systems, along with an outlook on the potential of combined enhancement technologies.