Kralj, Damir; Brečević, Ljerka
Precipitation of some slightly soluble salts using emulsion liquid membranes.
Croatica Chemica Acta, 71
Emulsion liquid membranes were used for precipitation of different sparingly soluble salts: calcium oxalate, copper oxalate, nickel oxalate, cobalt oxalate, lanthanum oxalate, calcium phosphate, cobalt phosphate, copper phosphate, lanthanum phosphate, barium sulphate, strontium sulphate and calcium sulphate. For the transport of a desired cation or anion from the feed into the stripping solution, where the precipitation occurred, one of the commercial ligands (bis(2-ethylhexyl)phosphoric acid, D2EHPA; 2-hydroxy-5-nonyl-acetophenone oxime, LIX 84; trioctylamine, ALAMIN 336) dissolved in kerosene, was used as a carrier. The precipitates obtained were characterized by means of transmission electron microscopy, X-ray diffractometry, FT-IR spectroscopy and thermogravimetry. The effect of the transport mechanism on the properties of salt precipitated was studied on calcium and copper oxalate model systems. It was found that copper oxalate hemihydrate and calcium oxalate monohydrate precipitated regardless of whether oxalic acid or a cation (calcium or copper) was transported into the stripping solution. It was also found that the particles of the precipitate were smaller when oxalic acid was transported.
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