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Abstract
The preparation procedure for nanoparticles of the water-soluble salts Na^sub 2^S and ZnSO^sub 4^, two commonly used reagents to synthesise ZnS nanoparticles, by evaporation of volatile components of salt-containing water-in-oil microemulsions is described. In suitable conditions, the evaporation leads to the formation of dry salt-surfactant composites and to the formation of Na^sub 2^S or ZnSO^sub 4^nanoparticles. It was found that the salt-surfactant composites can be totally redissolved in a dry apolar organic solvent allowing the formation of virtually water-free solutions containing a considerable amount of the water-soluble salts. The presence of nanoparticles in these solutions and in the composites has been proved by small-angle X-ray scattering and transmission electron microscopy, respectively. By mixing these solutions, the solid-solid reaction between Na^sub 2^S and ZnSO^sub 4^ nanoparticles leading to the formation of very small-sized ZnS nanoparticles has been ascertained by UV spectrophotometry.[PUBLICATION ABSTRACT]