Synthesis, Characterization, and Sorption Properties of Amorphous Titanium Phosphate and Silica-Modified Titanium Phosphates

Abstract

Amorphous titanium hydroxyphosphate with formula Ti(OH)(1.36)(HPO(4))(1.32).2.3H(2)O and a new silica-modified titanium hydroxyphosphate with a general formula Ti(OH)(2x)(HPO(4))(2-x).ySiO(2).nH(2)O are synthesized and characterized using IR, TG, XRD, SEM, solid-state NMR, and BET techniques. It is concluded that SiO(2) is evenly distributed within the titanium phosphate (TiP) agglomerates and that neither the separate silica phase nor the titanium silicates are formed during the synthesis of silica-modified titanium hydroxyphosphate. Correlations between the texture, ion-exchange properties of the amorphous titanium hydroxyphosphate, and the amount of SiO(2) present within the TiP matrix are established. Sorption properties of silica-modified titanium hydroxyphosphate toward Cs(+) and Sr(2+) are studied in a series of samples with an increasing amount of silica, at different pH, and in NaCl solutions with a varying ionic strength. It is found that sorption of Cs(+) does not depend practically on the amount of SiO(2) present, whereas the Sr(2+) uptake drastically decreases with an increase of silica amount. The effects of pH and of the electrolyte concentration on the sorption behavior of titanium phosphate are discussed in terms of ionic hydration shell and titanium phosphate structural specificity. The kinetics of sorption processes is also investigated, and the diffusion coefficients for cesium and strontium are obtained.

Sorption performances of TiO(OH)(H2PO4)·H2O in synthetic and mine waters

“…The amorphous TiP sorbents are oen characterized with steady increasing sorption of L-type. 14,17 To the best of our knowledge, these are the rst reported sorption data for amorphous TiO(OH)(H 2 PO 4 )$H 2 O sorbent with only H 2 PO 4 -active exchange units, displaying H-type of sorption. Table 1 displays the sorption parameters (including the correlation coefficient R 2 ) related to the ion-exchange process of the metal ions on Na-TiP1 in accordance with all three models (Langmuir, Freundlich and Temkin).…”

“…13,14 The exchange capacities of TiP sorbents have also been found to depend considerably on the pH of the solution. 15 17 that is a relatively low capacity for these systems. Therefore, there is a need to develop a TiP sorbent that brings together relatively mild synthetic conditions and a relatively high ion-exchange capacity.…”

“…on sorbents containing -HPO 4 functional units. 4,10,13,17,21,[23][24][25] Reports on sorption of transition metals ions on -H 2 PO 4 based TiP-IE have been scarce and mostly related to the Ti 2 O 3 (H 2 PO 4 )$ 2H 2 O sorbent. The Temkin approach has not been explored for modeling the sorption processes on Ti-IE.…”

Thermally modified molybdenum oxide as a potential sorbent for the removal of metal cations from aqueous solutions

“…5 whereas in Table 2 literature data concerning the sorption capacity of several sorbents (for the same metals and under similar experimental conditions) are presented for comparison [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62][63]. Taking into consideration the literature data and the findings of this study one can conclude that the investigated MoO 3 can be used for sorption of Ba, Cs and Eu from aqueous solutions as well as is an excellent sorbent for removal of Pb and U.…”

Treatment of Apatite Nepheline Ore Wasteenrichment Waste

“…The final solid was dried initially on air and then at 70 о С. Precipitation degree of titanium (IV) when producing titanium phosphate is 95-99%. The final silica titanium phosphate composite with formula Ti(OH) 2(1-x) (HPO 4 ) x ·ySiO 2 ·nH 2 O can be used as an ion-exchanger (Figure 6e) ( (Maslova et al, 2008). The silicium component facilitates pelletizing of the material.…”