Solvent Extraction and Separation of Niobium and Tantalum by Monooctylester of Anilinobenzylphosphonic Acid

The extraction of niobium and tantalum from aqueous solutions of their oxalato and fluoro complexes h as been studied, using the monooctylester of anilinobenzylphosphonic acid (MOABP) as extractant. The dependence of the extraction of niobium a nd tantalum upon th e hydrochloric, sulphuric, nitric, perchloric, phosphoric, hydrofluoric and oxalic acid concentration is described. A procedure for the separation of niobium from tantalum has been established. The back-extraction of niobium and tantalum from the organic phase was carried out with hydrofluoric, phosphoric a nd oxalic acid. The dependence of the extraction of niobium upon the MOABP concentration in the organic phase, and oxalic or hydrofluoric acid in the aqueous phase was also· studied. It was found that the distribution coefficients for niobium from oxalate solution were proportional to the second power of the MOABP concentration. The loga rithmic de p endence of the distribution coefficients for niobium from fluoride solution vs. the MOABP concentration gave a curve whose slope was 1.5. The extraction of niobium from oxalate solution is linearly proportional to the oxalic acid conce ntration, while the extraction of niobium from fluoride solution depends upon the second power of the hydrofluoric acid concentration. Similar experiments with tantalum were not made because of its very low extraction under the same conditions. The radionuclides 95Nb and 1s2Ta were used for the dete rmination of the distribution coefficients of niobium and tantalum in all of the experiments described

Tectonic Interrelation of the Dinarides and the Southern Alps

The study focuses on northwestern Croatia which, including the Zumberak (Zumberacka Gora), Medvednica (Zagrebacka Gora), Kalnik, Ivanscica, and Ravna Gora mountains, make a cross area of the Slovenian “Sava Folds”, Southern Alps, Mid-Transdanubian Zone, Tisia, and the Inner Dinarides. This is a complex structural region and cannot be attributed merely to one of the units. Therefore, a geotectonic interpretation is proposed which respects the diversification and multiple superposition of basinal and platform elements. This concept allows linkage of the Slovenian Trough with the Bosnian Zone and its southeastern prolongation as a major coherent tectonic unit overlain by different nappe elements. The possible linkage with the Budva Zone beneath the carbonate nappe is also discussed

Methorics of the Precipitation Processes. XVI. A Study of the Precipitation of Sparingly Soluble Metal Iodates

The precipitation phenomenology of silver, lead, and lanthanum iodates in aqueous electrolytic solutions and the concentration regions of their separation as solid phase were investigated. Only in the case of silver iodate the limiting concentrations for precipitation were concordant to the solubility concentrations of some other authors. It seems that in solutions with great excess of metal ions complex ionic species of the type [MenI03]n-1 are formed. In all three cases there exist differences between the limiting concentrations for the precipitation and the ionic solubility values. The precipitation curves of metal iodates show only one maximum which extends from the complex solubility limit at high metal concentrations to the another boundary at low concentrations

A Light Scattering and Electron Microscope Examination of Monodispersed Metal Iodate Hydrosols

Monodispersed lanthanum and lead iodate hydrosols were prepared and their properties examined by means of light scattering, electron and light microscopy, and measurements of rate of deposition of particles. The sols exhibited brilliant colour bands of higher order Tyndall spectra indicating the presence of spherical particles very uniform ill sizes. Lead iodate sols, otherwise very unstable, could be stabilized by simple filtration through filter paper. This was accompanied by reversal of charge carried by the particles. The growth of lanthanum iodate was much slower. Angular distribution of light scattered by metal iodates showed typical features of monodispersed systems with spherical particles several hundred millimicrons in radius. This was confirmed by electron microscopy. Particles of a typical lanthanum iodate sol were about 700 mμ in radius, and those of lead iodate about 860 mμ. The variations in particle sizes from different preparations were considerable, and could be explained by the uncontrolled influence of the direct mixing of reacting solutions. A tentative mechanism of the formation of monodispersed metaliodate hydrosols was proposed

A Note on the Preparation and Optical Properties of Monodispersed Lead Iodate Hydrosols

When a beam of white light is passed through an aerosol or a hydrosol, in which the radii of the spherical particles are very uniform and comparable in magnitude to the wave lengths of the incident light, brilliant colours appear in the light scattered at well defined angles

Continental Subduction Tectonics in the High Karst Dinarides of Western Croatia

The faults confining Palaeozoic inliers surrounded by Mesozoic rocks, show that their relation is not a consequence of folding but of neotectonic uplift causing a rather uneven relief of the Palaeozoic units underlying the carbonate Mesozoic. The predominance of tectonic contacts indicates that similar relations exist even between the Triassic and the confined Jurassic outcrops exhibiting inverse and, consequently, allochthonous relations. The allochthony is also confirmed by karst relief within some Triassic dolomites related to the unexpected ground water flow between the swallow holes (ponors) and karst springs. There are also indications of inverse relations between the Triassic volcanics and Palaeozoic clastics. However, in the surrounding area a normal superposition between the Triassic and Jurassic is also noticed. Consequently the Triassic and Jurassic of the Fuzine-Lokve area and of its environs may belong to two megatectonic units. Tectogenesis is explained by continental subduction of the Adriaticum under the Dinaricum

Application of 1-(4-Tolyl)-2-methyl-3-hydroxy-4-pyridone for the Extraction and Spectrophotometric Determination of Iron(III)

The application of 1-(4-tolyl)-2-methyl-3-hydroxy-4-pyridone (HY) to the extraction and spectrophotometric determination of iron (III) are described. In the aqueous phase iron (III) and HY form two different complexes; FeY2+ and FeY2+, depending on the iron-HY concentration ratio and the pH of the solution. It was found that only the FeY2+ complex is extracted into chloroform

Extraction and Spectrophotometric Determination of Iron(III) by 1-phenyl-2-methyl-3-hydroxy-4-pyridone

The extraction and spectrophotometric determination of iron (III) by 1-phenyl-2-methyl-3-hyd:roxy-4-pyridone (HX) are described. At pH > 1.5 97°/o of the iron(III) can be extracted. A quantitative reextraction of iron from the organic phase is possible with an acid concentraicm higher than 1 M. The composition of the iron(III)-HX complex formed tn the organic phase was investigated spectrophotometrically, radiometrically and by a quantitative analysis of the isolated species. In the aqueous phase iron(III) and HX form three different complexes, depending on the initial iron(III)HX concentration ratio and the pH of the solution. They are the violet Fex2+, the orange-red Fex2+ and the orange-yellow FeX3. The latter is identical with the complex found in the organic phase