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The blue species of molybdoslllclc acid Is strongly adsorbed on Sephadex gels. About 70% of the species In a 100-cm3 sample solution is concentrated In 0.20 g of Sephadex G-25 within half an hour. A sensitive method, gel-phase colorimetry, based on the direct measurement of light absorption by a gel phase, which has adsorbed the blue species, has been developed. The optimum condition for color development In the gel phase has been examined on the basis of the procedure In ASTM D859-80 or JIS K0101. The colored gel beads

Polymerization of silicic acid adsorbed on iron (III) hydroxide from dilute monosilicic acid solutions in the concentration range 5–40ppm (SiO2) was studied over the pH range 6–12. Silicic acid species formed on the hydroxide were trimethylsilylated and trimethylsilyl derivatives were detected by gas chromatography. Monosilicic acid adsorbed polymerized, and dimer (Si2O76−), linear trimer (Si2O108−) and tetramer (Si4O1310−), and cyclic tetramer (Si4O128−) were found as polymeric species.

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