Synthesis of nanoporous zirconium oxophosphate and application for removal of U(VI)

Uniformly arrayed zirconium-phosphate nanoporous material was synthesized, characterized, and used as an adsorbent for removal of U(VI) in a NaNO3 solution with varying background conditions including pH, ionic strength, U(VI) concentrations, and carbonate concentrations. Batch U(VI) adsorption results showed that U(VI) adsorption reached steady-state condition within 48 h, and all the dissolved U(VI) (10−6 M) was removed by this material at neutral pH and closed conditions to atmospheric CO2(g). The U(VI) adsorption followed a traditional Langmuir adsorption isotherm, and the distribution coefficient (Kd) calculated from the linear region of the Langmuir isotherm was 105,000 mL g−1. Because this phosphate-bearing nanoporous material exhibits high thermal stability and has a very high Kd value, it can be applied as an efficient adsorbent for removing U(VI) from various contaminated waste streams, such as those present at the US Department of Energy defense sites and the proposed geologic radioactive waste disposal facility at Yucca Mountain in Nevada.