The absorptiometric determination of zirconium by means of alizarin-S with special reference to magnesium alloys

Abstract

I t , is shown that the coloured reaction product of zirconyl ions and alizarin sulphonate is of definite compositioii and stable in acid solution. The reaction is almost specific for zirconium and can be used for its determination in magnesium alloys, iron and steel, and. minerals. A rapid method for determining the approximate composition of hafniumzirconium salt mixtures is also indicated.The method compares favourably in accuracy, speed and cost with the standard gravimetric procedure.THE determination of zirconium in magnesium alloys assumed major importance when the remarkable mechanical properties of these alloys was realised. They are to-day one of the major groups of magnesium-base alloys widely used in aircraft construction. The composition generally varies within fairly narrow limits, and the alloys may contain up to 5 per cent. of zinc, 3 per cent. of rare earths (of the Mischmetall type), and not more than about 1 per cent. of zirconium. A small proportion of the alloys contains thorium. The zirconium is present to a large extent in solid solution, 1 per cent. representing its solid solubility. A small fraction of the zirconium is present as internietallic compounds with iron, manganese, aluminium and silicon; these are insoluble in magnesium and only sparingly soluble in mineral acids, but are soluble in hydrofluoric acid. In general, the insoluble portion is of little interest and, for the purpose of analysis, the only account ta.ken of it is in specifying the concentration and amount of acid used for solution.The method of analysis laid down in D.T.D. specifications involves solution in acid, separation of zirconium with ammonium hydroxide, separation from rare earths by hydrolysis with hexamine, precipitation of zirconium arsenate and ignition, removing arsenic by treatment with sugar charcoal during a further ignition and weighing as the oxide. Although accuracy can belattained by this procedure it is tedious, lengthy and expensive; silica crucibles used for the determination rarely outlast four ignitions without seriously flaking. Furthermore, the conversion factor is rather large (0.7403).The same criticisms apply to the many organic precipitants of the arsonic acid type. Precipitation as phosphate necessitates preliminamy separations, and the ignited precipitate Sept., 19521 OF ZIRCONIUM BY MEANS OF ALIZARIN-S 477of pyrophosphate is frequently grey in spite of prolonged ignition, and sometimes contains slightly less zirconium than would correspond to ZrP,O,.A great deal of literature has appeared recently recommending various organic precipitants for separating zirconium from rare earths and thorium; these include mandelic acid,l@-chloro-and fi-bromo-mandelic acid and other glycollic acid derivatives,,~~ phthalic acid,4 sodium flavianate? m-cresoxyacetic acid,6 hydrazine sulphate,' t a n ~~i n , ~J aneurine and adenylpyrophosphoric acid, lO and cupferron.11 With the exception of fi-bromo-mandelic acid all these reagents finally yield the oxide, so that comparatively large weights of sample a...

Determination of Zirconium in Uranium Fissium Alloys

“…Niobium, molybdenum, antimony, ruthenium, palladium, tungsten, ferric ion, aluminum, thorium, rhodium, titanium, and organic hydroxy acids interfere with the spectrophotometric method for zirconium (4, 11,17). Ruthenium is the worst offender, causing an error in the zirconium equivalent to 10% of the weight of the ruthenium.…”

“…In the manufacture of the fuel elements, analyses for zirconium, as well as the other fissium elements, were needed for control of the process. The alizarin sulfonate method (2,11) for the spectrophotometric determination of zirconium in the presence of uranium is now being used in this laboratory for the analysis of other alloys. A differential spectrophotometric method is suggested for good precision by Manning and White (10).…”

Spectrophotometric Determination of Zirconium in Thorium

“…These include p-dimethylaminophenylazobenzenearsonic acid (5), alizarin (3,8), Alizarin Red S [8,4,[9][10][11]14), purpurin, (3,8) quinalizarin (3,8), thoron (6), and chloranilic acid (10,18). In their present form, these methods are time-consuming or require the removal of thorium if present in large amounts.…”

Review - Nonferrous Metallurgy

“…An indirect polarographic method for zirconium based on precipitation as the m-nitrobenzoate followed by measurement of the wave height corresponding to the first reduction of the nitrobenzoic acid was developed by Graham, Van Dalen, and Upton (64)• A rapid colorimetric method for zirconium in magnesium alloys using alizarin red S was reported by Wengert for the range 0.1 to 1%, with accuracy corresponding to that obtainable gravimetrically (190). Mayer and Bradshaw used the same reagent for this determination, showing it to be highly useful for minerals and ferrous alloys as well as magnesium (111). The)' also employed this method for determining the approximate composition of hafnium-zirconium mixtures.…”