Barium sulphate, precipitation

M. C. van der Leeden and co-workers, "Role of Polyelectrolytes ia Barium Sulphate Precipitation," Innovators Digest, RepofiNo. D221H, Technical University of Delft, The Netherlands, 1991. 

Baldyga, J. and Orciuch, W., 2001. Barium sulphate precipitation in a pipe - an experimental study and CFD modelling. Chemical Engineering Science, 56(7), 2435-2444. 

Kim, W.-S. and Tarbell, J.M., 1996. Micromixing effects on barium sulphate precipitation in an MSMPR reactor. Chemical Engineering Communications, 146, 33-56. 

Since, however, K2 is comparatively large, the solvent effect is relatively small this is why in the quantitative separation of barium sulphate, precipitation may be carried out in slightly acid solution in order to obtain a more easily filterable precipitate and to reduce co-precipitation (Section 11.5). 

Nielsen, A.E. (1958) The kinetics of crystal growth in barium sulphate precipitation. Acta Chem. Scand., 12, 951-958. 

Takiyama, K. (1959a) Formation and aging of precipitates. X. An electron micro-diffraction study on crystal habit of barium sulphate precipitates. Bull Chem. Soc. Japan, 32, 68-70. 

On account of the insolubility of these compounds and the difficulty of filtering and completely washing out the barium sulphate precipitate, in order to abstract from it the whole of the tyrosine, Abderhalden and Teruuchi, in the case of silk, have hydrolysed the protein with hydrochloric acid, the greater part of which was then removed by evaporation in vacuo the remainder of the hydrochloric acid was then estimated in a small aliquot portion, and then separated quantitatively by neutralising with the calculated amount of caustic soda. The tyrosine then crystallised out, and was purified by recrystallisation from water. 

Filter off the barium sulphate precipitate and evaporate the solution in a porcelain bowl first on a flame up to one-fourth of its initial volume, and then in a water bath until dry, Rapidly cool the hot bowl with cold water to facilitate the separation of the precipitate. Extract the hydroxylamine chloride from the solution, for which end transfer the triturated substance into a flask with a reflux condenser, pour in 30 ml of ethanol, and heat it on an electric stove with an enclosed heating element up to boiling. Pour off the liquid into a beaker and treat the solid substance again with 15 ml of ethanol. Combine the ethanol extracts, filter them through a crucible with a glass filtering bottom, and then evaporate the filtrate in a water bath up to the beginning of crystallization. 

To prepare potassium trioxalatoferrate(III), put 1.25 g of iron(III) sulphate, the prepared barium oxalate, 1.5 g of potassium oxalate, and 30 ml of water into a 500-ml beaker. Heat the mixture for several hours in a water bath, maintaining a constant volume. After separation of the barium sulphate precipitate, evaporate the filtrate to a volume of 5 ml and cool it. Filter off the potassium trioxalato-ferrate(III) crystals, rinse them with a small amount of water and then with ethanol, and dry them in a vacuum-desiccator over sulphuric acid. Write the equations of the reactions. 

In the commoner cases the base is a hydrated metallic oxide (of aluminium, tin, lead, zinc or, less often, chromium, iron, copper, antimony) to which the colouring matter (if acid) is united by true chemical combination tannin lakes are also made (with basic colouring matters). In other lakes the base is an inert substance (barium sulphate, precipitated alumina and silica, chalk, gypsum, kaolin, etc.), on which the colouring matter is fixed by simple mechanical absorption. Lakes of the former kind may be mixed, either fraudulently or for the purpose of attenuating the colour, with inert materials. 

Von Weimarn (1908) investigated the dependence on reagent concentration of the particle sizes of barium sulphate precipitates formed in alcohol-water mixtures by the reaction... 

Barium sulphate precipitate may also be dissolved in a hot 3 to 5 per cent solution of disodium ethylenediamine tetraacetate (Na2EDTA) in the presence of ammonia. 

The test is usually carried out by adding the reagent to the solution acidified with dilute hydrochloric acid carbonates, sulphites, and phosphates are not precipitated under these conditions. Concentrated hydrochloric acid or concentrated nitric acid should not be used, as a precipitate of barium chloride or of barium nitrate may form these dissolve, however, upon dilution with water. The barium sulphate precipitate may be filtered from the hot solution and fused on charcoal with sodium carbonate, when sodium sulphide will be formed. The latter may be extracted with water, and the extract filtered into a freshly prepared solution of sodium nitroprusside, when a transient, purple colouration is obtained (see under Sulphides, Section IV.6, reaction 5). An alternative method is to add a few drops of very dilute hydrochloric acid to the fused mass, and to cover the latter with lead acetate paper a black stain of lead sulphide is produced on the paper. The so-called Hepar reaction, which is less sensitive than the above two tests, consists of placing the fusion product on a silver coin and moistening with a little water a brownish-black stain of silver sulphide results. 

When the two solutions are mixed the barium ions and sulphate ions bond together, because they are strongly attracted to each other. Solid barium sulphate precipitates. 

Calcium cyclamate may be present with saccharin salts in pharmaceutical preparations the latter may be determined, after preliminary extraction of interference with chloroform, by ultra-violet absorption at 266 m/t or by extraction with ether from an acidified solution and then using one of the methods given above, such as fusion and barium sulphate precipitation. 

Sulphate ions in the extracts are precipitated by barium ions. After a clean up, the barium sulphate precipitate is dissolved by EDTA. The solution is then nebulised into an argon plasma, where all components are vaporised. Sulphate ions decompose the sulphur atoms thus formed are excited and then emit radiation of which the intensity is measured at a wavelength of 181.972 nm. 

The combined determination of total Cu, Ba and Y is possible by dissolving a weight of powder in 1 M HCl. On treatment with sulphuric acid, barium sulphate precipitates and weighed. The filtrate containing Cu and Y is then treated with S02/SCN solution when Cu is precipitated as thiocyanate and weighed. The filtrate contains Y which is determined by EDTA titration or assayed spectrophotometrically. 

Sulphamic acid solution liberates sulphate ions slowly on boiling. When mixed with the barium solution, barium sulphate precipitates slowly giving a more easily filtrable precipitate. NH2S0jH+H20-+NH4++S04 -+H+... 

A summary of the analysis is given in Anal.Proceedings,l%%) 992) il. Using m g of superconductor, if the mass of barium sulphate precipitate is mi. 

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