FUNTIONALIZATION OF TITANIUM DIOXIDE SURFACE WITH PHOSPHONIC ACIDS

The article presents the results of the study of synthesis and properties of highly dispersed titanium dioxide TiO2 and preparation of chemically modified carriers based on it. Titanium dioxide obtained by alkaline hydrolysis of TiCl4 with subsequent heat treatment has been characterized by XRD, BET and thermogravimetry methods. It was found that the synthesized TiO2 has crystallographic parameters corresponding to the anatase structure with an average crystallite size of 10 nm, a high specific surface area (119 m2/g) and a high content of surface OH groups (12,6 OH groups/nm2). A simple one-step method has been developed for the chemical modification of the anatase surface with phosphonic complexones - nitrilotri(methylphosphonic) acid (NTMP) and N-(phosphonomethyl)iminodiacetic acid (PMIDA The formation of a phosphonic coating occurs due to the attachment of one of the phosphonic groups of the complexon to the surface, and the remaining free functional groups of complexons give the surface new properties. The presence of fixed complexons on the surface of anatase is confirmed by IR spectroscopy, acid-base titration, and sorption measurements. An increase in the degree of sorption of the cationic dye toluidine blue from aqueous solutions at pH 1-5 by modified anatase compared with the initial anatase was found. The increase in sorption capacity was caused by the presence on the surface of strongly acidic phosphonic -PO(OH)2 and carboxyl groups -COON, carrying a negative charge, while the surface of the initial anatase is positively charged with Ti-OH2+. The resulting new carrier can be used in a variety of catalytic and electro/photo catalytic processes, as well as for concentration/sorption extraction of various cations (metal ion, dyes).