The effect of P/Ti ratio in titanium phosphate on the adsorption U(VI) in aqueous solution

Abstract Titanium phosphate (TiP) exhibits significant potential for the removal of U(VI) from aqueous solutions. In this study, tetra-n-butyl titanate (TBOT) and phosphoric acid were employed as titanium and phosphorus sources, respectively, and the P/Ti ratio was varied during the hydrothermal synthesis. Both amorphous and α-type TiPs were successfully synthesized, and their physicochemical properties at different P/Ti ratios were characterized using XRD, FTIR, SEM, zeta potential, and TG analysis. The effects of pH and P/Ti ratio on adsorption performance were systematically investigated, revealing that all TiPs achieved maximum adsorption capacity at pH 7.0. The adsorption behavior conformed to the Langmuir model, with a theoretical maximum adsorption capacity of 266.4 mg g −1 at a P/Ti ratio of 2. In the presence of multiple competing ions, amorphous TiP demonstrated higher selectivity for U(VI) compared to α-type TiP. Mechanistic studies indicated that U(VI) adsorption primarily occurs via surface complexation and ion exchange processes on the TiP surface. Overall, the adsorption efficiency of U(VI) can be effectively optimized by adjusting the P/Ti ratio in TiP.