The enrichment process of rare earth elements in ion-adsorbed rare earth ores and bauxite is potentially related to the adsorption of rare earth elements by gibbsite. In this paper, lanthanum and yttrium were selected as surrogates of light rare earth elements and heavy rare earth elements, respectively. The effects of adsorption time, solution pH, and background electrolyte concentration on the adsorption of rare earth ions by gibbsite were investigated through batch adsorption experiments. The results showed that the adsorption of rare earth ions by gibbsite can approach equilibrium in 72 h. There is mainly electrostatic repulsion between gibbsite and rare earth ions at pH 4–7, and the adsorption efficiency increases with the increase in solution pH value and background electrolyte concentration. The adsorption process of rare earth ions by gibbsite is more consistent with the pseudo-second-order kinetic and Langmuir single-layer adsorption models. Moreover, based on the structural correlation between clay minerals and gibbsite, the causes for the differences in the adsorption behaviors of rare earth elements on the minerals are discussed. The results of this study help to understand the role of aluminum hydroxide in the migration and fate of rare earth elements in epigenetic environments.Keywords:gibbsite;rare earth element;adsorption;kinetics;thermodynamics
A non‑aqueous separation strategy that combines acetonitrile (ACN) with 1, 3‑propanediol (PDO) is presented for the 90 yttrium(III)/ 90 strontium(II) (Y(III)/Sr(II)) separation. In an initial dissolution step, the ACN-PDO mixture displays a pronounced solubility contrast between Y nitrate (1.22 g/100 g) and Sr nitrate (0.09 g/100 g), enabling the selective dissolution of trace Y(III) while Sr(II) remains largely undissolved. Furthermore, ACN-PDO mixture also exhibits favorable physicochemical properties, e.g., relatively low viscosity (about 40 mPa·s), a suitable density difference (0.25 g/cm 3 ) from n -octane, and lower miscibility with n -octane, for constituting an extraction system with N,N,N’,N’ tetra-octyl-3-oxopentanediamide in n -octane, in which both Y(III) extraction efficiencies and separation factors greatly exceed those of aqueous-based extraction systems. Density functional theory calculations also confirmed that the Y/Sr separation is more favorable in ACN-PDO/ n -octane systems compared to water/ n -octane systems due to differences in solvation effects and contact ion pairs. A practice integrated separation process achieved a Y(III) recovery of >90 % with product purity exceeding 99 %. The overall decontamination factor (>460,000) is markedly higher than the values reported for existing aqueous‑based methods.
Graphical Delete hysteresis? Efficient and hysteresis-less perovskite solar cells are prepared by using YCl 3 -treated TiO 2 electron transfer layers. The YCl 3 treatment increases the film conductivity and raises the lower boundary of the TiO 2 conduction band. The average device efficiency reaches approximately 18.82 %, owing to better energy level alignment and favorable charge transfer. Hybrid organic–inorganic metal halide perovskite solar cells have attracted widespread attention, owing to their high performance, and have undergone rapid development. In perovskite solar cells, the charge transfer layer plays an important role for separating and transferring photogenerated carriers. In this work, an efficient YCl 3 -treated TiO 2 electron transfer layer (ETL) is used to fabricate perovskite solar cells with enhanced photovoltaic performance and less hysteresis. The YCl 3 -treated TiO 2 layers bring about an upward shift of the conduction band minimum ( E CBM ), which results in a better energy level alignment for photogenerated electron transfer and extraction from the perovskite into the TiO 2 layer. After optimization, perovskite solar cells based on the YCl 3 -treated TiO 2 layers achieve a maximum power conversion efficiency of about 19.99 % (19.29 % at forward scan) and a steady-state power output of about 19.6 %. Steady-state and time-resolved photoluminescence measurements and impedance spectroscopy are carried out to investigate the charge transfer and recombination dynamics between the perovskite and the TiO 2 electron transfer layer interface. The improved perovskite/TiO 2 ETL interface with YCl 3 treatment is found to separate and extract photogenerated charge rapidly and suppress recombination effectively, which leads to the improved performance.
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