Use of organic reagents in inorganic analysis

Summary Eighteen anilic acids have been prepared from maleic anhydride and various aromatic amines and their properties and analytical reactions with various metal ions have been studied. The acid prepared from benzidine was insoluble in all common solvents and, hence, its application could not be studied. Most of these reagents, except those obtained from aniline, o- and p-chloroanilines, nitranilines, p-amino-acetanilide and o-phenylenediamine, produced more or less quantitative precipitations with both thorium and zirconium. Their actions towards thorium and zirconium were very much alike. They also gave precipitations with mercury(I), lead and cerium(IV), but such precipitations were not complete. Ferrous iron showed greyish turbidity with most of the reagents, but ferric iron produced colourations varying from brown to violet, such colours were, however, found to be unstable either on standing for a while or on heating. Gold and platinum underwent reduction in presence of these reagents.Part VIII: See Z. analyt. Chem. 163, 403 (1958).The work has been carried out in the chemical laboratories of Darjeeling Government College, Darjeeling. The author is grateful to the authorities of the College for the laboratory facilities.     

Organic azo-dyes in quantitative analysis

Summary Chrom red brown 5RD was used as an indicator for complexometric titration of thorium. The change in the colour at the end-point was from wine-red to yellow. It is recommended that the thorium buffered aliquot should not contain less then 200 g thorium per 10 ml for a precise estimation. A range of p_H from 2.5 to 3.5 has been found satisfactory for such a titration. Ferri, ferro and zirconium ions interfere; they should be separated beforehand.Part I: Zaki, M. R., and K. Shakir: Z. analyt. Chem. 174, 274 (1960).     

Analytical aspects of some azo dyes from chromotropic acid

Summary Nitroso-SNADNS-4, itself a yellow coloured dye in acid medium forms a reddish-pink colouration with thorium in weakly acid solution. The colour is stable for about 24 hours and to a temperature up to 50C. The thorium complex shows maximum absorbance at the wave length 520 m, while that of the dye occurs at 430 m. The maximum intensity of colour of the thorium complex is shown at aph 2.5. The colour system conforms to Beer's law in a wide range of concentration of thorium and presents a reliable method for the spectrophotometric determination of the metal even in presence of a large number of common ions, the ions interfering are: tin, iron, nickel, cobalt, cerium(IV), zirconium, gold, phosphate and fluoride. The average percentage of deviation of the absorbance index in the determination of thorium is 1.14.Part VI: See Z. analyt. Chem. 167, 105 (1959)     

Diphenic acid as an analytical reagent

Summary Diphenic acid can separate thorium completely from moderate amounts of ferrous iron and titanium in almost neutral solutions. As the reagent forms quantitative precipitates with ferric iron and zirconium, workable methods for their separation from thorium and their co-determinations in a mixture with the help of this reagent have also been developed. The reagent can separate thorium from zirconium by precipitating the latter below p_h2, and the same from iron(ic) can be accomplished by the use of ascorbic acid as a masking agent. Ferric iron can be precipitated from solution containing ascorbic acid, by the ammonium salt of the reagent. A convenient process for the estimation and separation of zirconium, thorium, iron(ic) and titanium, when present in a mixture, has also been described, which involves the proper control ofph and the use of ascorbic acid as a complexing agent for ferric iron.My sincere thanks are due to Dr. A.K. Mukherjee of the Indian Association for the Cultivation of Science, Calcutta for his valuable suggestions and to Dr. A. K. Ghosal, Principal, Darjeeling Government College for providing laboratory facilities.     

Organic azo-dyes in quantitative analysis

Summary Chrom Red Brown 5 RD has been found as a sensitive reagent for the spectrophotometric determination of thorium. Concentrations as low as 1 g thorium/1 ml can be easily determined at wave length 485 nm. Sulphate, chloride, ferric and zirconium ions badly interfere, while Li, Na, K, Ni, Co, Cu²+, Cd, Ca, Mg and Cr³⁺ do not. U⁶⁺ and Ce⁴⁺ are permissible as traces.Part II: Zaki, M. R., and K. Shakir: Z. analyt. Chem. 177, 196 (1960).     

Use of organic reagents in inorganic analysis

Summary Thorium and zirconium have been determined gravimetrically with phenylglycine-p-carboxylic acid and zirconium alone with phenylglycine-o-carboxylic acid, almost within the same pH range. Better results are obtained when zirconium is precipitated in acetic acid solution in presence of a little ammonium acetate. A number of foreign ions may be separated from thorium and zirconium with these reagents. Iron and titanium cause heavy interference. The interference caused by iron, may however, be eliminated by adding a little ascorbic acid, before precipitation of the metals. The para acid can also extract thorium from a mixture of cerite earths and from monazite sands.Part V: See Z. anal. Chem. 158, 347 (1957).The author likes to thank Dr. B. N. Bose, Principal of the College and Dr. S. K. Sinha, the Head of the Department of Chemistry for their kind advice and encouragements.     

Rapid titrimetric determination of thorium with fluoride using SPADNS

Summary A rapid titrimetric method for the estimation of thorium in the range from 5 to 88 mg. in a 50 ml. of final volume has been developed which involves the adjustment of P_h at 3.0, addition of 2 ml. of 0.02% SPADNS indicator, dilution to volume and titration with standard NaF until the colour obtained matches a blank containing the buffered solution of the indicator alone. The method has been standardised against known amounts of thorium and a calibration curve relating the titre of the fluoride solution to thorium content has been prepared. Interferences of various cations and anions have also been studied. From the results, the quantitative nature of zirconium interference has been confirmed. The method for the determination of thorium is very rapid and the colour change being sharp from blue-violet to scarlet-red, the detection of endpoint is not at all difficult.The author wishes to thank Dr. A. K. Ghosal, Principal, Darjeeling Government College, for providing Laboratory facilities and Prof. P. Ray and Dr. A. K. Mukherjee of the Indian Association for the Cultivation of Science, Calcutta for their encouragement in the research work.     

Anwendung von Silicagel in der anorganischen Analyse. Abtrennung des Thoriums von Zirkonium

Zusammenfassung Die Sorption des Thoriums und Zirkoniums an Silicagel aus ÄDTA und Weinsäure wurde verfolgt. Bei ph 7 in Gegenwart von Weinsäure durchläuft das Zirkonium die Silicagelkolonne, während Th(IV) quantitativ sorbiert wird. Diese Tatsache wurde zur Trennung des Thoriums von Zirkonium im Konzentrationsverhältnis 1200 angewandt. Da Zr(IV) aus 0,5-n HCl quantitativ sorbiert wird, woraus die Th(IV)-sorption praktisch gleich Null ist, kann auf diese Weise Zr(IV) von einem beträchtlichen Überschuß an Th(IV) getrennt werden. Die Trennung ist noch im Verhältnis 11000 quantitativ.

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Summary The sorption of thorium and zirconium on silica gel from EDTA and tartaric acid was followed. At ph 7 and in the presence of tartaric acid, the zirconium passes through the silica gel column, whereas Th(IV) is sorbed quantitatively. This finding was employed for the separation of thorium from zirconium in a concentration ratio of 1200. Because Zr(IV) is quantitatively sorbed from 0.5N HCl, while the sorption of Th(IV) is practically zero from this medium, Zr(IV) can be separated from a considerable excess of Th(IV) in this way. The separation is still quantitative at a ratio of 11000.

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Résumé On a suivi l'adsorption du thorium et du zirconium sur silicagel à partir d'EDTA et d'acide tartrique. A pn 7, en présence d'acide tartrique, le zirconium traverse la colonne de silicagel, alors que le thorium-IV est adsorbé quantitativement. On a mis à profit cet état de fait pour séparer le thorium du zirconium pour des concentrations dans le rapport 1200. Comme le zirconium-IV est adsorbé quantitativement à partir d'HCl 0,5N, tandis que l'adsorption du thorium-IV est alors pratiquement nulle, on peut séparer de cette manière le zirconium-IV d'un excès important de thorium-IV. La séparation est encore quantitative pour le rapport 11000.

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Herrn Prof. Dr. Ing.M. Jureek zum 60. Geburtstag gewidmet.     

Rapid extraction of copper(II) with 2-thenoyltrifluoroacetone direct colorimetric determination in the organic phase

Summary The chelating agent, 2-thenoyltrifluoroacetone has been employed for rapid extraction and colorimetric determination of milligram amounts of copper(II) in one operation. At pH 2.4–6.0 copper(II) is extracted quantitatively from an aqueous solution by TTA-benzene in a single extraction. The green-coloured copper(II)-TTA chelate solution in benzene obeysBeer's law at 430 m over the range of 16–180g copper per millilitre. The coloured system is stable for 143 hours. It can tolerate silver, mercury(II), bismuth (<5 mg) and small amounts (<100 mg) of citrate and tartrate, whereas cobalt(II), nickel(II), iron(III), aluminium(III), cerium(IV), thorium and zirconium seriously interfere. The proposed method is reproducible to within ±1.4%.     

Estimation of natural thorium in low level effluents from processing plants

This is a report of simple estimations of natural thorium in low level effluents generated during the reprocessing of irradiated Th/ThO₂ rods for the recovery of²³³U. The method involved co-precipitation of thorium with ceric iodate at pH 1.29±0.01 and subsequent photometric determination. Conditions were optimised to eliminate the interferences of other ions present in the effluent. Approximately 15 mg each of phosphate, fluoride, and sulphate, 10 mg of iron, and 300 g zirconium did not interfere in the estimation of 2–5 g Th/100 ml of the effluent. Average thorium recovery was around 101.9%±2.6% when nearly 10 g of thorium were spiked.     

Diphenic acid as an analytical reagent

Summary Diphenic acid behaves as a selective reagent for the estimation of thorium in presence of phosphate, arsenate, molybdate, alkaline, earths, copper, cadmium, lead, bismuth, tin, aluminium, chromium, nickel, cobalt, zinc, manganese, magnesium and palladium. Thorium can be successfully separated from the cerite earths by the reagent from solutions having thoria: earth oxide ratio 126 by single precipitation and by double precipitation when the above ratio is 144. The reagent can separate thorium from solutions having ThO₂U₃O₈ ratio upto 180 by double precipitation. The metal can also be recovered from monazite sands.Thanks are expressed hereby to Dr. A. K. Ghosal, Principal, Darjeeling Government College and Dr. A. K. Mukherjee of Indian Association for the Cultivation of Science, Calcutta, for their kind encouragement and to the Government of India, Ministry of Natural Resources and Scientific Research for a gift of Indian Monazite for analysis.     

The anilic acid number,an analytical index for testing dibasic acid anhydrides

For testing the purity of dibasic acid anhydrides and for analysing mixtures of these anhydrides with the corresponding free acids the determination of a new index number is recommended, indicated as the “anilic acid number”. The process is based on the fact that these acid anhydrides, when dissolved in acetone, under suitable experimental conditions can be added readily and quantitatively to aniline with resulting formation of the corresponding anilic acids.Immediately after addition, titration is effected with alcoholic potassium hydroxide on phenolphthalein. Pure dibasic acid anhydrides in this case yield the calculated anilic acid number. In the presence of free acids the values found are too high. The free acid content can be easily determined from the difference between the theoretical and the found anilic acid number.     

Thiodiglycolic acid as a reagent for zirconium

Thiodiglycolic acid is shown to be a suitable precipitating reagent for zirconium. The analysis is completed by igniting the precipitate and weighing the ZrO₂. Several metal ions do not interfere. Interference due to cerium(IV) is avoided by reducing it initially to cerium(III). Estimation of zirconium can be carried out in presence of thorium. The composition of the Complex is slightly variable but corresponds to zirconyl thiodiglycolate: O =

     

Gravimetric determination of thorium and zirconium

Summary Thorium and zirconium can be quantitatively precipitated by quinaldinic acid atph 2.7 and 3, respectively. As the precipitates are of nonstoichiometric composition they are to be ignited to oxides. By this reagent thorium can be quantitatively separated from arsenic (As³⁺), mercury (Hg²⁺), rare earths, manganese, magnesium and alkaline earths and zirconium from all the aforesaid ions excepting rare earths which contaminate to a slight extent.     

Analytical aspects of some organic acids

Summary Back titrimetric procedures for the estimation of aluminium, zirconium, and thorium have been developed, which involved the adjustment of the concentration of the metallic salts, concentration of EDTA,ph, and temperature, addition of indicator solution (namely, 2-hydroxy3-naphthoic acid and back titration with standard 0.1 M ferric chloride solution. This method is based on the fact that the excess EDTA, which is added to the metal solutions may be back titrated with iron(III), which forms a highly coloured complex with the indicator, when present in slight excess. Quantities of aluminium, zirconium and thorium as small as 10.8, 4.6, 11.6 mg respectively, can be back titrated with in experimental error, when present in a volume of 100 ml.Part IV: See Z. analyt. Chem. 172, 356 (1960).     

Extraction of U(VI), Th(IV) and some fission products from nitric acid medium by sulfoxides and effect of γ-irradiation on the extraction

The extracting abilities for thorium, uranium and some fission products by five sulfoxides are given. The results show that di(2-ethylhexyl) sulfoxide (DEHSO) is not only completely miscible with kerosene, but also superior to tri-n-butyl phosphate in some properties. The extraction behavior of uranium, thorium and some fission products such as zirconium, niobium and ruthenium from aqueous nitric acid with DEHSO in kerosene has been studied over a wide range of conditions. DEHSO extracted uranium and fission products better than TBP under all conditions and is similar to TBP in extraction of thorium. A study of extraction mechanism indicates that U and Th are extracted as disolvates, whereas HNO₃ is extracted as monosolvate. Extraction of the two actinides decreases with increasing temperature, indicating the extraction to be exothermic. Preliminary studies show that -ray irradiated DEHSO extracts Zr and Nb to a smaller extent than irradiated TBP in the range of 10⁴–10⁷ rad.     

Synthesis and properties of phosphate cation-exchangers based on silica

Methods of preparation of silicas with chemically grafted molecules of aryl- and alkylphosphonic acids in the amount of 0.7–1.2 molecules/nm² (sorbentes I and II) are described. The spectra of the sorbents in the near and fundamental IR regions were obtained. The protolytic properties of attached phosphonic acids with a different ionic strength of the solution were studied. The value of for grafted arylphosphonic acid (1.9) coincides with = 1.83 for p-tolylphosphonic acid in aqueous solution. Sorption of iron(III) and thorium(IV) ions on these sorbents was studied. A high degree of extraction of thorium (>90% for sorbent I and >60% for sorbent II) is observed up to 4 M HCl. Iron(III) is sorbed in less acid media. A method of concentration of thorium(IV) from dilute solutions with a concentration coefficient of 10² and a method of separating thorium(IV) from 1000-fold amounts of iron(III) are proposed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 6, pp. 711–716, November–December, 1987.