ABSTRACT 5,8-diethyl-7-hydroxy-6-dodecanone oxime(LIX 63) and bis(2,4,4-trimethylpentyl)dithiophosphinic acid (Cyanex 301) can selectively extract Pd(II) over Pt(IV) from HCl solutions. Comparative studies have shown that although Cyanex 301 exhibits a higher extraction efficiency for Pd(II) than LIX 63, the subsequent stripping of Pd(II) from the loaded Cyanex 301 phase is extremely difficult. In contrast, thiourea can readily strip Pd(II) from the loaded LIX 63 phase, demonstrating a more practical regeneration process. In the HCl concentration ranges of 1–9 M, Pd(II) was selectively extracted over Pt(IV) by LIX 63 but its extraction percentage was rapidly decreased when HCl concentration was higher than 5 M. Moreover, LIX 63 selectively extracted Pd(II) over Pt(IV) within the concentration ratio of Pt(IV) to Pd(II) up to 30. According to slope analysis, the extraction of Pd(II) by LIX 63 involves protonation of the nitrogen atom, followed by nucleophilic addition of the PdCl₄²⁻ anionic complex. This proposed mechanism is consistent with the experimentally determined loading capacity of LIX 63 for Pd(II), confirming the validity of the reaction pathway.

ABSTRACT The annular centrifugal contactor (ACC) is an efficient extraction and separation equipment. The effects of structure and operation parameters on the hydrodynamic characteristics in the mixing zone of the annular centrifugal contactor have been reported, while the effects of physical properties of extraction systems on the hydrodynamic characteristics in the mixing zone of the ACC have less been reported. In this paper, the effects of organic phase viscosity (μ o), two-phase density difference (ρ a-ρ o), and interfacial tension (γ) of extraction systems on the hold-up volume, hold-up (x d), residence time (t m), phase ratio (o/a) (Φ o/a), and flow pattern in the mixing zone of the ACC were systematically investigated using the fast-liquid-separating method. The x d decreases with increasing in Taylor number (Ta). The residence time (t m) and phase ratio (o/a) increase with the increase of organic phase viscosity, while have no significant change with two-phase density difference and interfacial tension of extraction systems. Reynolds number (Re) and Taylor number increase as the viscosity of the mixed phase decreases When Re >3215 and Ta >325, the flow pattern in the mixing zone is turbulent vortex flow, which facilitates mass transfer. The experimental results provide guidance for the operation of extraction systems in annular centrifugal contactor

ABSTRACT Organic extractant-functionalized superparamagnetic nanoadsorbents represent a novel generation of advanced functional materials with many potential applications for separation and purification of metal ions in hydrometallurgy. In this study, tributyl phosphate (TBP) organic extractant is employed to explore the preparation of TBP-functionalized iron oxide-based nanoadsorbents. Accordingly, the synthesized superparamagnetic magnetite (Fe3O4) nanoparticles are first surface-modified with stearic acid surfactant and then functionalized with various concentrations of TBP at different temperatures. A single layer extractant is physically adhered to the surface of stearate-modified nanoparticles via Van der Waals forces. From an adsorption viewpoint, statistical error analysis suggests that the Langmuir isotherm model best describes the TBP physisorption, with a maximum adsorption capacity of 368.3 mg.g−1 at the optimal temperature of 25 °C. Thermodynamic investigations based on the Van’t Hoff relation reveal that the process is exothermic in nature (ΔH° ads = -20.8 kJ.mol−1), lowers the system’s randomness (ΔS° ads = -57.4 J.mol−1.K−1), and proceeds favorably.

ABSTRACT The effective separation of trivalent actinides (An3+) from lanthanides (Ln3+) is of great significance for the sustainable development of nuclear industry. Prior studies have demonstrated that the purified Cyanex 301 (bis(2,4,4-trimethylpentyl) dithiophosphinic acid, HBTMPDTP) exhibits exceptional An3+/Ln3+ selectivity and such a system has been extensively validated over the past decades, showcasing promising industrial application potential. To further advance the practical implementation of this system in a real scenario, a hot test based on Cyanex 301 is imperative to be conducted. In this work, the separation of An3+/Ln3+ ions was achieved within a buffer system through saponification or synergistic modifications through 5-stage batch cross-current extraction process, with optimal operational parameters identified. On this basis, two optimized demonstrations of the “Cyanex 301+ process” were conducted using 14-stage centrifugal contactors: one involving formic acid buffer-mediated saponification extraction and the other employing formic acid buffer-mediated TBP synergistic extraction. A complete An3+/Ln3+ mutual separation was accomplished with >99.9% An3+ recovery and >99.98% Ln3+ rejection. Excellent product/feed decontamination factors over 1900 and 1600 for An3+ were obtained for the demonstration process without and with TBP, respectively. This study successfully demonstrates the high-efficiency and reliability of the Cyanex 301+ process for treating genuine fuel solutions.

ABSTRACT Palladium (Pd), a member of the platinum group metals (PGMs), possesses unique properties that make it indispensable across various fields, including electronics, catalysis, jewelry, automotive applications, and hydrogen storage. However, the limited availability of natural Pd sources is insufficient to meet the growing global demand, highlighting the need for alternative and sustainable sources. One promising secondary source is high-level liquid waste (HLLW), a by-product generated during the reprocessing of spent nuclear fuel. HLLW from pressurized heavy water reactors (PHWRs) has been reported to contain approximately 165 mg/L of Pd. During the reprocessing of one ton of spent nuclear fuel with a burnup of 6700 MWD/te in a PHWR, nearly 800 liters of HLLW is produced. Thus, nuclear waste offers a valuable and underutilized resource for Pd recovery. This article explores various materials that have been successfully employed to selectively extract Pd from HLLW using methods such as adsorption, solvent extraction, and ion exchange. However, reported materials for Pd recovery often suffer from limitations such as poor selectivity, low reusability, and slow kinetics. These shortcomings underscore the need for further development of more efficient and sustainable methods for Pd uptake from HLLW.

ABSTRACT In this study, we selectively removed fluoride ions (F−) from simulated iodine-containing wastewater using zirconium silicate (ZrSiO4). Zirconium silicate could selectively adsorb F− in solutions with coexisting anions such as sulfate, chloride, bromide, iodine, and borate. The simulated iodine-containing catalytic wastewater contained fluoride (2.6 mmol/L (50 mg/L)) and iodine (630 mmol/L (80 g/L)) ions with the pH adjusted to 2 using sulfuric acid. Fluoride was selectively adsorbed from the simulated iodine-containing wastewater to final concentrations of below the target value to recover iodine for fluoride (0.42 mmol/L (8 mg/L)) with iodine remaining at the initial concentration (630 mmol/L). The desorption of fluoride using an alkaline solution (NaOH) was more effective than with using NH3 and Na2CO3, and the cycle stability of the adsorbent was high. ZrSiO4 granules can be prepared from ZrSiO4 powder using water glass binder by heating at 400°C. In the chromatographic separation analysis, F− were effectively adsorbed on the adsorbent packed into the column, whereas iodine ions (I−) were scarcely adsorbed. In the desorption stage, the concentration of F− was seven times that of the initial concentration in the feed solution in the adsorption stage, whereas little iodine was eluted. A molar selectivity coefficient of F−/I− of up to 1600 was achieved.

ABSTRACT Among radionuclides used for targeted radionuclide therapy in nuclear medicine, rhenium-188 radioisotope is of particular relevance. No-carrier-added (NCA) 188Re was produced at the Egyptian Second Research Reactor (ETRR-2) by neutron irradiation of natural tungsten target via indirect nuclear reaction. The radiochemical separation of 188Re from irradiated tungsten target was investigated based on solvent extraction technique using Aliquat 336. Several separation parameters were checked and optimized. The batch experimental results indicated that an extraction % of 95% was obtained at pH 4, 0.1 M of Aliquat 336, and 1.5 h extraction time for extraction of 188Re, while for 187W it was around 19% at these conditions. Finally, 188Re was purified from the irradiated tungsten target by the utilization of 1 M HNO3 as a stripping agent. The stripped fractions of 188Re were of high chemical, radiochemical, and radionuclidic purity.

ABSTRACT In this study, the chemical reactivity of three organophosphorus acidic extractants (D2EHPA, PC 88A, and Cyanex 272) was compared for the extraction of the anionic gold(III) complex, AuCl4 −, from the concentrated hydrochloric acid solutions. The extraction behavior was examined by varying the hydrochloric acid concentration from 1 to 9 M. Among the three extractants, only Cyanex 272 showed significant efficiency in extracting Au(III) with the extraction percentage was proportional to hydrochloric acid concentration. In contrast, the extraction of Au(III) by D2EHPA and PC 88A was not significant. FT-IR spectra analysis indicated that the P=O bond in Cyanex 272 weakened after extraction, suggesting its involvement in the process. Based on the structural differences between the extractants and the observed dependence of gold(III) extraction on the hydrochloric acid concentration, a nucleophilic addition reaction was proposed as the extraction mechanism. Specifically, the phosphoryl oxygen of protonated Cyanex 272 likely forms a coordinate bond with the gold ion in AuCl4 −, facilitating its extraction. This mechanism was supported by both extraction and spectroscopic data, making Cyanex 272 a promising candidate for the selective extraction of Au(III) from highly acidic solutions. The findings offer insights into the extraction of metal ions using organophosphorus extractants in highly acidic environments.

ABSTRACT This study investigates the performance of Lewatit TP 260 ion exchange resin for the efficient recovery of lithium (Li(I)) from geothermal water sourced from the Germencik Geothermal Power Plant in Türkiye. A series of batch sorption experiments were performed to evaluate the influence of key parameters, including resin dosage, solution pH, temperature, initial Li(I) concentration, and contact time, on the Li(I) recovery process. The optimal conditions were determined to be a resin dose of 0.5 g per 25 mL of geothermal water, pH in the range of 6–8, and a temperature of 25°C. Under these conditions, the resin achieved a maximum Li(I) recovery rate of 71% from the geothermal water. Sorption isotherms were further analyzed using the Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) models. Among these, the Langmuir model provided the best fit (R² = 0.9841), suggesting a maximum sorption capacity (qm) of 4.31 mg/g. Continuous recovery experiments conducted in column mode confirmed the practical applicability of Lewatit TP 260, achieving a total sorption capacity of 0.41 mg Li(I)/mL resin. The findings exhibit the potential of this resin as a viable sorbent for sustainable Li(I) extraction from geothermal brines, supporting the development of green energy technologies and contributing to the circular economy.