Nickelic fluoride sulphate

Sulphuric acid is not recommended, because sulphate ions have a certain tendency to form complexes with iron(III) ions. Silver, copper, nickel, cobalt, titanium, uranium, molybdenum, mercury (>lgL-1), zinc, cadmium, and bismuth interfere. Mercury(I) and tin(II) salts, if present, should be converted into the mercury(II) and tin(IV) salts, otherwise the colour is destroyed. Phosphates, arsenates, fluorides, oxalates, and tartrates interfere, since they form fairly stable complexes with iron(III) ions the influence of phosphates and arsenates is reduced by the presence of a comparatively high concentration of acid. 

A Study was carried out with a large number of individual and mixed waste waters in test plants at pressures of 150-200 bar, temperatures of 543-603 K (270-330 °C) and with variations of the chloride, sulphate, and phosphate concentrations, the pH values as well as the COD values (Chemical Oxygen Demand). The following metallic materials were examined in this study with regard to their suitability in wet oxidation plants for industrial waste waters chromium-nickel-molybdenum steel 1.4571 (X6CrNiMoTil7-12-2), titanium, tantalum, and nickel. None of the investigated materials was resistant at acidic pHs. At pH values > 7, titanium and tantalum were resistant, even in the presence of low fluoride concentrations and chloride concentrations of up to 100 g/1 [50]. 

Mellon and its application to pharmaceuticals by Strafford, Wyatt and Kershaw. The colour is fully developed in five minutes and remains stable for several hours comparatively small amounts of strong alkalies cause instability of colour, and oxidising agents should be avoided. Aluminium, if present, must be kept in solution with an excess of tartaric or citric acid. Cobalt and chromium seriously interfere and so does nickel if present in large quantity. The effect of small amounts of copper is negligible, and of the salts of common acids, chlorides, sulphates, fluorides and phosphates have no effect. 

Salts of heavy metals such as copper, gold, silver, mercury, tin, lead, nickel, and cobalt (to cite only the most common ones) all are aggressive towards aluminium, whatever the associated anion, such as chloride, sulphate or fluoride. 

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