MULTIFUNCTION ADSORPTION MATERIALS .1. INTERACTION OF URANIUM AND CRYSTALLINE TIO2.MH(2)O MODIFIED BY AMORPHOUS SIO2.NH(2)O

The crystalline hydrous titanium dioxide modified by amorphous hydrous silicon dioxide (CTDASD), 2SiO(2).3TiO(2).6H(2)O has been synthesized by ageing the amorphous mixed silicon-titanium hydroxide at 80 degree s C for 36 hours. The prepared material possesses adjustable selectivi ty and apparent ion exchange capacity for a certain element or even fo r a group of elements. XRD, TGA and pH titration have been employed to characterize the prepared material. The uptake of uranyl ions on CTDA SD is independent of concentration of sodium ions under the experiment al conditions investigated, suggesting the material synthesized is rel iable to remove uranyl ions from the media of high salt concentration. The uptake of uranium on the CTDASD is remarkably sensitive to the so lution pH and reaches the maximum at pH 4.5. Plot of log K-D, of urani um versus equilibrium pH generates a series of lines with the mean slo pe of 0.63 at pH 1-->4, indicating the sophisticated loading mechanism s in (H) over bar/UO22+ reaction.