Enhancing radiostrontium uptake by a layered titanate perovskite via sustainable electrochemically switched ion exchange.

Abstract

Green and sustainable ⁹⁰Sr uptake is urgently needed for radionuclides remediation. Herein, we propose an efficient strategy based on electrochemically switched ion exchange (ESIX) method to enhance ⁹⁰Sr uptake using electroactive ion exchange material. A titanate perovskite (Na₂La₂Ti₃O₁₀) with outstanding acid, irradiation resistance, and thermal stability can effectively capture Sr²⁺ and achieve remediation of actual acidic ⁹⁰Sr-containing liquid waste (R^Sr > 99%). Na₂La₂Ti₃O₁₀ is prepared as working electrode C@NaLaTiO to enhance Sr²⁺ uptake via ESIX. Remarkably, the Sr²⁺ adsorption capacity increases (from 104.84 to 175.43 mg·g^-1) and high selectivity for Sr²⁺ is maintained even under strongly acidic solutions. The Sr²⁺ adsorption-desorption can be controlled via facile potential modulation. Mechanism study indicates that efficient Sr²⁺ capture originates from the ion exchange between Sr²⁺ and interlayer Na⁺ in Na₂La₂Ti₃O₁₀ coupled with the electrochemical redox reaction between Ti⁴⁺/Ti³⁺ and the increase in oxygen vacancy. Density functional theory calculations support that ESIX enhances Sr²⁺ adsorption by increasing the binding energy of anionic [La₂Ti₃O₁₀]_n^2n- layers towards Sr²⁺. This study offers a convenient and environmentally friendly way for the efficient ⁹⁰Sr enrichment from radioactive waste liquids.