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The physicochemical characteristics of single and mixed zirconia and silica gels produced by the sol-gel technique at different synthesis pH and sequence of introducing the reagents in the mother liquid are presented. As a result of comparing the data obtained by different research methods, it is found that in the mixed gels, irrespective of the synthesis technique, Si-O-Zr bonds are present. The introduction of a zirconium salt in the mother liquid containing a silicate salt leads to the preferred formation of zirconia gel granules of 20-30 nm in diameter enclosed in the matrix of silica gel. The inverse sequence of introducing the gel-forming components in the reaction mixture promotes the formation of large gel aggregates containing the particles of less that 10 nm and having a high degree of polymerization. Mixed gels of zirconium oxyhydrate and silicic acid have an order higher sorptive capacity for yttrium (III) and calcium cations, as compared to single silica gels and zirconia gels.

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