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Precipitation of Thorium Hydroxide in the Presence of Gelatin and Sodium Nitrate

Božica Šuveljak-Žuljević ; Department of Chemistry, Faculty of Education, University of Osijek, Osijek, Croatia
Ranko H. H. Wolf ; Ruđer Bošković Institute, P. O. Box 1016, Zagreb, Croatia
Svetozar Musić ; Ruđer Bošković Institute, P. O. Box 1016, Zagreb, Croatia

Puni tekst: engleski pdf 29.448 Kb

str. 331-344

preuzimanja: 286



The precipitation of thorium(IV) hydroxide and its interactions with gelatin were investigated in the system: gelatin - Th(N03>4 - NaNO.-j - (HNO3 or NaOH). The samples were prepared by mixing the aqueous solutions of the system components and kept at 293 K. The HN03 and NaOH were pH-adjusting components, while NaNOs uncoiled gelatin molecules, thus enhancing their interacting power. The precipitation systems were investigated using nephelometry, microelectrophoresis, X-ray diffraction, IR spectroscopy and scanning electron microscopy. In dependence on pH, the characteristic sequence of states was observed: clear solution I, gel (very turbid, strong, elastic and thixotropic), clear solution II and flocks settled as sediment. This sequence of states was discussed with regard to three processes that occur with pH-increase: (a) hydrolysis of Th4+ ions followed by formation of hydroxy complexes and colloidal thorium(IV) hydroxide, (b) dissociation of the functional groups of gelatin and (c) interaction between the Th(NC>3)4 component and gelatin. It was shown that the gel state consisted of colloidal particles of thorium(IV) hydroxide, which were linked by uncoiled gelatin molecules into a network of gel structure.

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