Controlled fabrication of flower-like α-zirconium phosphate for the efficient removal of radioactive strontium from acidic nuclear wastewater

Abstract

Highly efficient and low cost removal of radioactive ⁹⁰Sr from high level liquid waste (HLLW) is a key step for safe and long-term storage of nuclear waste. Herein, for the first time, we reported a novel flower-like α-ZrP material, which was prepared via a simple and economical low-temperature solid state synthesis approach. The formation mechanism of flower-like α-ZrP was investigated by changing the reaction time, temperature and phosphate precursor. Remarkably, the flower-like α-ZrP possesses desirable properties: a large surface area, and excellent resistance to acid and radiation, promoting its application in HLLW disposal. A batch of adsorption experiments indicated that flower-like α-ZrP exhibits great efficiency for the removal of Sr²⁺ from aqueous solution, and the maximum monolayer adsorption capacity for Sr²⁺ is 293.43 mg g⁻¹, which surpasses those of most of the reported adsorbents. The improved adsorption ability is mainly attributed to the larger surface area of the flower-like morphology of α-ZrP, which provides many more adsorption sites for strontium ions. Moreover, the flower-like α-ZrP shows particular selectivity for the removal of Sr²⁺ from a simulated HLLW (1 M HNO₃ solution, containing about 13 different kinds of metal elements). The adsorbed Sr²⁺ ions can be effectively stripped with a dilute HCl solution, and the regenerated α-ZrP adsorbent can be re-used at least five times without significant loss of Sr²⁺ adsorption capacity. Besides, the concrete mechanism of the strontium–adsorbent interaction was also demonstrated in this contribution. Our preliminary results suggested that flower-like α-ZrP could be potentially used as a highly effective material for the enrichment and removal of radioactive strontium from HLLW.