Degradation of organothiophosphorous extractant Cyanex 301

Extraction of the trivalent transplutonium actinides americium through einsteinium by the sulfur donor Cyanex 301

When extracting metals with the sulfur donor ligand, Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid), a transition in the coordination mode of extracted complexes has been observed between Eu and Gd, but not within the actinide series.

Review on the Comparison of the Chemical Reactivity of Cyanex 272, Cyanex 301 and Cyanex 302 for Their Application to Metal Separation from Acid Media

Cyanex extractants, such as Cyanex 272, Cyanex 301, and Cyanex 302 have been commercialized and widely used in the extraction and separation of metal ions in hydrometallurgy. Since Cyanex 301 and Cyanex 302 are the derivatives of Cyanex 272, these extractants have similar functional groups. In order to understand the different extraction behaviors of these extractants, an understanding of the relationship between their structure and reactivity is important. We reviewed the physicochemical properties of these extractants, such as their solubility in water, polymerization degree, acidity strength, extraction performance of metal ions, and the interaction with diluent and other extractants on the basis of their chemical structure. Synthetic methods for these extractants were also introduced. This information is of great value in the synthesis of new kinds of extractants for the extraction of metals from a diverse medium. From the literature, the extraction and stripping characteristics of metals by Cyanex 272 and its derivatives from inorganic acids such as HCl, H2SO4, and HNO3 were also reviewed. The replacement of oxygen with sulfur in the functional groups (P = O to P = S group) has two opposing effects. One is to enhance their acidity and extractability due to an increase in the stability of metal complexes, and the other is to make the stripping of metals from the loaded Cyanex 301 difficult.

Recovery of cobalt from dilute aqueous solutions using activated carbon–alginate composite spheres impregnated with Cyanex 272

Waste water was purified from cobalt(ii) and manganese(ii) by adsorption and desorption on shaped and impregnated activated carbon spheres.

f-Block complexes of a m-terphenyl dithiocarboxylate ligand

Homoleptic thorium(iv), uranium(iv), and lanthanum(iii) dithiocarboxylate complexes were prepared and studied electrochemically; the lanthanum complex was found to bind toluene.

Photodegradation of Hydrophobic Pyridineketoximes in Toluene and Heptane

The goal of the research was to study the reactivity of the hydrophobic 2- and 3-pyridineketoximes under exposure to UV-VIS light. The photodegradation was conducted in both toluene and heptane for 10 h under atmosphere of argon. Ten-hour irradiation experiments demonstrated that the pyridineketoximes underwent the facile E-Z photoisomerization, photo-Beckmann rearrangement, and to a lesser extent, the photosubstitution to the pyridine ring. From LC-MS and NMR analysis of the irradiated solutions, it was found that the photosubstitution proceeded to give the corresponding 6-substituted 2- or 3-pyridylketoxime via the replacement of the ring hydrogen by the benzyl or heptyl group. The photo-Beckmann rearrangement led to the formation of the corresponding amides, but also other products formed in the photo-decomposition reaction.

Oxidative degradation of bis(2,4,4-trimethylpentyl)dithiophosphinic acid in nitric acid studied by electrospray ionization mass spectrometry

RATIONALE

The selective separation of the minor actinides (Am, Cm) from the lanthanides is a topic of ongoing nuclear fuel cycle research, and dithiophosphinic acids are candidate ligands in these processes. Ligand instability has been noted under radiolytic and harsh acid conditions but explicit degradation pathways for ligands such as bis(2,4,4-trimethylpentyl)-dithiophosphinic acid (CyxH), the major compound in the commercial product Cyanex 301, have been elusive.

METHODS

Organic solutions of CyxH were contacted with aqueous solutions of HNO(3), and their degradation was studied by analyzing samples from these experiments by direct infusion electrospray ionization mass spectrometry. Ions were identified using accurate mass measurement and collision-induced dissociation.

RESULTS

The positive ion spectra contained cationized CyxH cluster ions, and oxidatively coupled species (designated Cyx(2)) cationized by either H or Na. The Cyx(2)-derived ions increased with acid contact time. The negative ion spectra consisted almost entirely of the CyxH conjugate base. The negative ion spectra of the HNO(3)-contacted samples also contained conjugate bases corresponding to the dioxo and perthio derivatives of CyxH.

CONCLUSIONS

CyxH is oxidized by acid contact to form the coupled species Cyx(2), and the dioxo species arise from subsequent oxidation of Cyx(2). Oxidative coupling increases with contact time, and with higher HNO(3) concentrations. The direct infusion measurements provided a simple approach for assessing degradation pathways and kinetics.