Jerome W. O'Laughlin

The determination of fluorine in rare earth fluorides by high temperature hydrolysis

The technique of pyrohydrolysis has been applied to the determination of fluorine in the fluorides of scandium, yttrium, and the lanthanons. These fluorides have been divided into two classes according to their rate of hydrolysls. Lutetium, ytterbium, cerium (III), scandium. gadolinium, terbium, dysprosium, holmium, erbium, and thulium auorides can be hydrolyzed in 30 min or less. Yttrium. lanthanum, praseodymium. neodymlum, samarium, and europium fluorides require from 45 to 150 min for complete hydrolysis. Accelerators, such as uranium oxide (U/sub 3/C/sub 8/), chromium(UI) oxide. and a mixture of these oxides have been used successfully to reduce the time required for quantitative hydrolysis of the fluorides in the latter group. The use of the correct accelerator reduces the hydrolysis time to 30 min or less for all these fluorides except lanthanum, praseodymium, and neodymium. (auth)

Reversed-phase paper chromatography of the rare earths, thorium and uranium using methylenebis(di-n-hexylphosphine oxide) as the stationary phase☆

Reversed-phase partition chromatography was used to separate the rare earths, thorium and uranium on papers treated with methylenebis(di-n-hexylphosphine oxide), MHDPO. The separation factors between adjacent rare earths were found to increase with the acid concentration in both nitric and hydrochloric media with the larger separation factors in nitric acid. Opposite trends were observed in hydrochloric and nitric acid. In the former case the partition coefficient increased with acid concentration, but in the latter case it decreased. This was explained on the basis of the solvation energies of the cations and anions, the mass action effect and the competitive extraction of nitric and hydrochloric acid. Solvation number studies indicated a 1:1 adduct between MHDPO and the rare earth nitrates. Corresponding studies on the rare earth chrlorides gave anomalous results. It was postulated this was caused by non-equilibrium conditions.

Separation of several rare earths by extraction chromatography using bifunctional phosphine oxides

Abstract Data are presented on the separation of various rare earth ions by extraction chromatography using methylenebis(di- n -hexylphosphine oxide), MHDPO, and methylenebis [di-(2-ethylhexyl)-phosphine oxide], MEHDPO, supported on kieselguhr, Kel-F, or Plaskon as stationary phases. The data suggest the particular support used for the extractant has little effect on HETP provided the particle size of the supporting material is the same. The observed K D and HETP values are shown to be relatively insensitive to moderate changes in the flow rate and temperature. Average values of HETP of approximately 1 mm were observed but values less than half that large were obtained in some cases. Elution curves for the separation of four adjacent rare earths (milligram amounts of gadolinium, terbium, dysprosium and holmium) are shown.

Reversed-phase partition chromatography of the rare earths using methylenebis[di(2-ethylhexyl)-phosphine oxide] as the stationary phase☆

RF values are given for the rare-earth nitrates, chlorides, and perchlorates on paper impregnated with methylenebis[di(2-ethylhexyl)phosphine oxide] (MEHDPO). The much lower 1/RF — 1 values for the rare-earth perchlorates on MEHDPO-treated paper than on paper treated with the analogous extractant without the ethyl groups in the 2-position (MHDPO) are rationalized on the basis of steric factors. The greater separation factors for the rate earths observed in the nitric acid system with MEHDPO are explained on the same basis.

Determination of aluminum in vanadium metal by atomic absorption spectrophotometry

Abstract The determination of aluminum in vanadium metal over the range 100 p.p.m. to 1% aluminum was investigated by atomic absorption spectrophotometry. Commercially available equipment with a nitrous oxide-acetylene burner was used. High concentrations of vanadium were found to influence the aluminum absorption in a variable manner depending upon certain conditions. Reproducible results could be obtained only by carefully matching the matrix and acid concentrations in the standards to that in the actual sample.