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Wet gel and dried xerogel of precipitated tin oxy-hydroxide were subjected to mechanochemical and microwave treatments (MChT and MWT, respectively). The prepared samples were studied using DTA-TG, XRD, FTIR, nitrogen adsorption-desorption. MChT and MWT cause improvement of crystal structure, removal of structural OH-groups and increase mesopores diameter as well as form the meso-macroporous structure. As a result, drastic increase of uranyl-ions sorption for all modified samples is observed. Sorption centers can be divided into three groups: selective cation-exchange, non-selective cationexchange and anion-exchange. Keywords SnO 2 • Mechanochemical and microwave treatments • Ion-exchange properties * Barbara Charmas

Mechanochemical modification of low-dispersed SnO 2 and high-dispersed SnO(OH) 2 powders with specific surface area 6 and 198 m 2 g À1 have been studied. The crystal, porous, and electronic structure of obtained products, as well as their photocatalytic activity under visible light in the process of dyes degradation has been investigated. It has been established that high-dispersed powder is porous and poorly crystalline. Its specific surface area decreases after milling. On the contrary, low-dispersed powder is almost nonporous and well crystallized. Its specific surface area increases but degree of crystallinity reduces as a result of milling. Milling of both powders in water leads to formation of meso-macroporous structure. The narrowing of band gap and increase of adsorption of visible light occur after modification of low-dispersed sample. As a result, photocatalytic activity of milled powders under visible irradiation significantly increases. Maximal activity showed high-dispersed sample milled in air and water.

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