Extraction of beryllium(II) from iodide solutions by tributyl phosphate

The distribution of beryllium between aqueous sulfuric acid/potassium iodide solutions and organic phases of tributyl phosphate is described. The dependence of extraction on the pH of the aqueous phase, metal and extractant concentration, diluent type and organic additive, has been investigated. Extraction mechanism is discussed on the basis of results obtained. A method for the separation and determination of beryllium, in a mixture of beryllium and aluminium (with other contaminants) is outlined.     

Complexes of biologically important ligands. I. Ternary complexes of nickel(II) comprising 1,10-o-phenanthrolineazosulfonamide derivatives and alkyldithiophosphates

5-[p-(R-Sulfonyl)phenylazo]-1,10-o-phenanthroline (L) and its octahedral complexes of the type [Ni(R₂dtp)₂(L)] (where R₂dtp = diethyl-or dipropyldithiophosphate) with the core NiN₂S₄ have been prepared and characterized by spectral, magnetic, and thermogravimetric methods. The thermal decomposition mechanism of the compounds was proposed and the kinetic parameters of decomposition were calculated making use of the Coats—Redfern and Horowitz—Metzger equations.     

The thermal diffusivity of natural rubber

Measurements of thermal diffusivities of peroxide-cured and sulfur-cured rubbers, over the range 0–100°C and 0–75 phr of carbon, are described. They are based on the asymptotic time dependences of heating and cooling curves, recorded following quenching of the samples into baths at various temperatures. The diffusivities are shown to depend linearly on both temperature and carbon content, to reasonable accuracies over the ranges studied. Some theory bearing on measurement techniques is presented.     

A thermometric study of the dissolution of copper in acid solutions

The dissolution of Cu in solutions of HNO₃ of different concentrations has been studied by the thermometric method. Starting from the initial temperature, T_i, the temperature—time curves exhibit an induction period followed by a rapid rise in temperature to a maximum value, T_m, attained t min after the start of the reaction. T_m increases and t decreases with increase of the acid concentration, M. ΔT (i.e.T_m ? T_i) and the reaction number (R.N. = (T_m ? T_i)/t) vary with M according to: ΔT = k(M ? M₀) and R.N. = A₁Mⁿ, where k, M₀, A₁ and n are constants.The effect of varying concentrations of HCl, H₂SO₄ and H₃PO₄ on the R.N. of Cu in 3.5 M HNO₃ was examined. Small amounts of these acids lower the R.N. (inhibition) due to the displacement of an active species on the surface of the metal by the anion of the acid. Larger additions of the acids accelerate dissolution. The concentration at which the added acid changes from corrosion-inhibitor to accelerator varies as HCl < H₂SO₄ < H₃PO₄. This sequence is considered to parallel the strength of adsorption of the respective anions. The results of experiments with salt additions confirm this view; all salts act only as dissolution-retardants. Calculations pertaining to the effect of the various ions on the R.N. support the conclusion that the dissolution of Cu in HNO₃ is autocatalytic in nature, and depends on the [H⁺]/[NO₃^?] ratio.Cu does not dissolve in air-free, cold HCl. Attack takes place, however, in the presence of KNO₃. Under these conditions attack is of the pitting- rather than the general type. The temperature rises suddenly after an incubation period, which decreases in length with increase of the amount of the added salt.Proof of the involvement of HNO₂ in the autocatalytic cycle of Cu dissolution in HNO₃ is obtained from the results of urea additions to the solution.     

Fast Navy 2 R as a colorimetric reagent for the determination of copper, manganese and zinc

Summary Solochrome Fast Navy 2R has been found to be a suitable colorimetric reagent for the determination of copper, manganese and zinc either in pure solutions or in mixtures. The range of determination varies between 0.5–4 g/25 ml. Study of the effect of time, temperature, p_H on the determination was carried out. The molecular ratio of the dyemetal complex was investigated using the slope ratio method.Tables for the various determination are given and show that the experimental errors are of satisfactory order. Good results were obtained by the use of EDTA, cyanide or thioglycollic acid to mask the various interfering cations.

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Zusammenfassung Solochrome Fast Navy 2R wird zur colorimetrischen Bestimmung von Kupfer, Mangan und Zink in reinen Lösungen oder in Mischungen empfohlen. Die erfaßbaren Mengen liegen im Bereich zwischen 0,5 und 4 g/25 ml. Die Genauigkeit der Ergebnisse ist befriedigend. Der Einfluß der Zeit, der Temperatur und des p_H-Wertes sowie das Molverhältnis im Metall-Farbstoff-Komplex wurden untersucht. Verschiedene störende Kationen konnten erfolgreich mit ÄDTA, Cyanid oder Thioglykolsäure maskiert werden.

     

Energy levels for the Coulomb potential with cut-off

Zusammenfassung Die Absorptionsbanden der Alkalihalogenidkristalle werden auf Elektronen zurückgeführt, die an leeren Gitterstellen eingefangen sind. Als Feld wird ein bei kleinen Distanzen horizontal abgeschnittenes Coulomb-Feld angesetzt. Die Eigenwerte werden im ganzen Energiebereich aus einer genauen Reihenentwicklung der Lösungen der Schrödinger-Gleichung bestimmt.     

Comparative study of metomega chrome blue BBL, calcon, eriochrome blue S.E. and omega chrome black blue G as indicators in the complexometric titration of calcium and magnesium

Conclusion It can be concluded that for the determination of calcium and magnesium in mixtures two separate titrations are to be done in case of Calcon, Erio SE, BBG. Total calcium and magnesium was determined first and then calcium in a separate titration. Magnesium is found by differences whereas in the case of BBL, the mixture was first titrated for its calcium content, then the solution is made acidic with hydrochloric acid and then alkaline with ammonia buffer solution pH 10 and magnesium is determined in the same sample.It is also noticed that Erio SE can work in sodium hydroxide or potassium hydroxid medium as well as in diethyl amine; but its drawback is the red hue which can be overcome by the addition of a green component, whereas BBL is spoilt in sodium hydroxide or potassium hydroxide medium.In comparing the first 3 indicators (Calcon, Erio SE, BBG) we find that BBG is the best one in the titration of calcium and magnesium using either EDTA on Complexion IV, and its endpoint has no red hue as that found in Erio SE; also the recovery of calcium is quantitative in any ratio of magnesium.

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Vergleichende Untersuchung von Metomega Chromblau BBL, Calcon, EriochromblauS.E.und Omega-ChromschwarzblauG als Inidicatoren bei der komplexometrischen Bestimmung von Calcium und Magnesium

     

Determination of antihypertensive mixtures by use of a chemometrics-assisted spectrophotometric method

A simple multivariate calibration method for analysis of two types of hypotensive mixture is described. The mixtures are composed of chlorthalidone with atenolol or chlorthalidone with both amiloride hydrochloride and atenolol. The components of the mixtures result in substantial spectral overlap—between 87.5 and 91.0%. Resolution of the mixtures under investigation has been accomplished mainly by using CLS and PCR methods. The components in each mixture have been simultaneously determined in three commercial dosage forms with high accuracy and without interference from commonly encountered excipients and additives. Good recoveries were obtained with both synthetic mixtures and commercial tablets. The results obtained were compared with those from pharmacopeial methods and found to be in good agreement. The results obtained from CLS and PCR were also compared with those obtained from a ¹D spectrophotometric method.