During the extraction of metal ions from a weak acidic chloride solution by ionic liquids consisting of an organophosphorus extractant and Aliquat 336, the equilibrium pH is sometimes observed to be higher than the initial pH. To compare the hydrogen ion extraction behavior of tertiary and quaternary amines, Alamine 336, Aliquat 336 and their mixture with Cyanex 272, and an ionic liquid (prepared by mixing Cyanex 272 and Aliquat 336, R 4 NA) were employed in solvent extraction experiments at a pH range from 0.05 to 5. R 4 NA showed the highest extraction percentage of hydrogen ions. The initial pH of the chloride solution had a great effect on the extraction of hydrogen ions and the equilibrium pH value produced by these extractants. The order of hydrogen ion extraction was R 4 NA>Alamine 336>mixture of Alamine 336 and Cyanex 272. The addition of sodium chloride improved phase separation. The solvent extraction reaction of hydrogen ions with R 4 NA in the chloride solution was verified by applying a slope analysis method to the extraction data. UV-Vis and FT-IR spectra indicated a strong interaction between the hydrogen ions and R 4 NA during the extraction. The obtained results provide some information on the change in solution pH during the extraction of metal ions from weak acidic solution by an ionic liquid (R 4 NA).
A complete recycling process for the cathode material of spent lithium-ion batteries is demonstrated with a simple two-step process comprised of one-pot cobalt recovery to nanostructured materials and single step synthesis of LiCoO 2 . For the facile and efficient recovery of cobalt, we employ malic acid as a leaching agent and oxalic acid as a precipitating agent, resulting in nanostructured cobalt oxalate. X-ray diffraction and Fourier transform infrared spectroscopy (FT-IR) analysis clearly show that cobalt species are simultaneously leached and precipitated as cobalt oxalate with a high yield of 99.28%, and this material can then be used as a reactant for the synthesis of LiCoO 2 for use as a cathode material. In addition to its advantages in simplifying the process, the proposed method allows for not only enhancing the efficiency of cobalt recovery, but also enabling reaction without a reducing agent, H 2 O 2 . Through successive single-step reaction of the obtained cobalt oxalate without any purification process, LiCoO 2 is also successfully synthesized. The effect of the annealing temperature during synthesis on the nanostructure and charge-discharge properties is also investigated. Half-cell tests with recycled LiCoO 2 exhibit a high discharge capacity (131 mA·h·g −1 ) and 93% charge-discharge efficiency.
In this study, a fabrication method of tapered microstructures with high aspect ratio was proposed by deep X-ray lithography. Tapered microstructures with several hundred micrometers and high aspect ratio are demanded owing to the high applicability in the fields of various microelectromechanical systems (MEMS) such as optical components and microfluidic channels. However, as the pattern and gap size were downsized to smaller micro-scale with higher aspect ratio over 5, microstructures were easily deformed or clustered together due to capillary force during the drying process. Here, we describe a novel manufacturing process of tapered microstructures with high aspect ratio. To selectively block the deep X-ray irradiation, an X-ray mask was prepared via conventional ultraviolet (UV) lithography. A double X-ray exposure process with and without X-ray mask was applied to impose a two-step dose distribution on a photoresist. For the clear removal of the exposed region, the product was developed in the downward direction, which encourages a gravity-induced pulling force as well as a convective transport of the developer. After a drying process with the surface additive, tapered microstructures were successfully fabricated with a pattern size of 130 μm, gap size of 40 μm, and aspect ratio over 7.
Cyanex 301 and 5,8-diethyl-7-hydroxyldodecane-6-oxime (LIX 63) can selectively extract Pd(II) over Pt(IV) from concentrated hydrochloric acid solutions. Therefore, solvent extraction experiments have been performed by extractant mixtures containing either Cyanex 301 or LIX 63, and the extraction behavior of Pd(II) was compared. Among the mixtures of Cyanex 301, the highest synergistic enhancement coefficient was achieved by mixing Cyanex 301 and trioctylphosphine oxide (TOPO). However, it was very difficult to strip the Pd(II) from the loaded mixture phase. Among the mixtures of LIX 63, the mixture of LIX 63 and alamine 336/TOPO enhanced the extraction of Pd(II). Although the synergistic coefficient by Cyanex 301 + TOPO was higher than that by LIX 63 + Alamine 336, the Pd(II) in the loaded mixture phase of LIX 63 and alamine 336 was easily stripped by thiourea.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.