Preparation of hollow α-ZrP spheres for cesium remediation

Traditional ZrP is considered an effective adsorbent for removal of 137Cs from aqueous solutions due to its excellent stability and adsorption properties. However, there is still some room to improve its adsorption capacity, to further its application to practical nuclear wastewater treatment. Here, we describe a novel hollow ZrP sphere adsorbent prepared by a simple template method. These spheres not only retain the excellent stability of traditional ZrP sheets, but are larger. A column loaded with hollow ZrP spheres exhibits high removal rates of Cs+ under both neutral and acidic conditions; the high capacity, rapid kinetics, and activity over a wide pH range are attributed to its larger size. Even in mixed solutions containing various metal ions, it still shows excellent selectivity for Cs+ ions. The Langmuir model and the pseudo-second-order model respectively fit the adsorption isotherm and kinetic data better, with a maximum adsorption capacity for Cs+ of 89.43 mg g−1, better than most other similar adsorbents. Moreover, the composite has excellent stability, and can be recycled and reused at least five times while retaining high removal efficiency for Cs+. These results suggest a new way to improve the traditional ZrP adsorbent, with benefits to practical nuclear wastewater treatment process.