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

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

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

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

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

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

Solvent Extraction and Separation of Europium(llI) and Terbium(Ill) from Uranium(Vl) by Monooctyl anilinobenzylphosphonate

The solvent extraction behaviour of Eu(III) and Tb(III) between aqueous solutions and a ligroin solution of monooctyl a-anilinobenzylphosphonate has been investigated. The distribution studies were carried out using the radionuclides 1s2Eu and 160Tb as tracers. Uranium was d etermined spectrophotometrically. The effect of varying the concentration of extractant in the or":anic phase and of varying the hydrogen ion concentration of the aqueous phase has been studied. Chloride, perchlorate, nitrate, and sulphate s olutions were employed as aqueous phases. The metal-ligand ratios of the extractable Eu(III) and Tb(III) complexes have been determined from log-log plots of the partition coefficients vs. the concentrations of extractant in the organic phase and hydrogen ion concentration in the aqueous phase. Conditions for the separation of Eu(III) and Tb(III) from U(VI) ai:;e given together with the separation coefficients which were found to range from 103 to 104,. The possibility of back-extracting the extracted uranium is discussed