Highly efficient removal of radioactive 90Sr based on sulfonic acid-functionalized α-zirconium phosphate nanosheets

Excellent column packing is a precondition for efficient separation of radioactive 90Sr from high level liquid waste (HLLW). α-ZrP particles are traditionally used as column packing for capturing radioactive nuclides from HLLW due to their excellent stability and adsorption ability. However, there remains room for improvement in terms of capacity and selectivity. Here, the traditional α-ZrP column packing was exfoliated and further modified by anchoring sulfonic groups on its surface to improve its adsorption capacity for 90Sr. The resulting ZrP-SO3H not only retained the excellent properties of α-ZrP but also possessed a larger surface area and much more adsorption sites. Adsorption experiments indicated that ZrP-SO3H exhibited excellent adsorption ability for separating of Sr2+ from acidic condition, and the maximum adsorption capacity of Sr2+ fitted by a Langmuir model is 183.21 mg g−1, which is higher than that of traditional α-ZrP and other similar column packings. In addition, kinetic studies indicated that Sr2+ adsorption on ZrP-SO3H is fast, and surface chemical adsorption is the main interaction between Sr2+ and ZrP-SO3H. Remarkably, radioactive experiment proved that ZrP-SO3H is an excellent adsorbent, and shows good stability for high efficiency for selective removal of 90Sr under complicate radioactive environment. Our present results implied that the novel ZrP-SO3H is potential column packing and could be suggested as promising column packing for separation of 90Sr from HLLW.