Effect of hydrolysis rate on the structure and properties of zirconium oxyhydrates.

The most widespread procedure for the synthesis of oxyhydrate materials by the sol-gel method is fast alkaline hydrolysis of the soluble salts of heavy metals. Oversaturation of the mother solution during fast hydrolysis provides high dispersity and hence large surface area and availability of the sorption centers of the aggregates being formed. The number and accessibility of sorption centers is also determined by the structure of gel particles. At low hydrolysis rates, there are good possibilities for the structural rearrangements of gel elements, which leads to the formation of ordered supramolecular structures with developed surfaces. The structural characteristics of zirconium gels obtained by fast (5 s), slow (5 days), and ultraslow (5 mos.) alkaline hydrolysis of zirconium oxychloride were determined by derivatography combined with mass and IR spectroscopy (of thermolysis products), X-ray diffraction, IR spectroscopy (xerogels), NMR, electron microscopy, and other methods. [ABSTRACT FROM AUTHOR]