Silica-based sulfonic acid-functionalized mesoporous composite for selective and fast removal of strontium from aqueous environments

A novel SiO 2 - P -SO 3 Na composite was synthesized via in-situ solution polymerization coupled with chemical grafting. • SiO 2 - P -SO 3 Na exhibits fast adsorption kinetics and high adsorption capacity for Sr(II). • Demonstrates excellent chemical stability and >99% Sr(II) removal efficiency after multiple regeneration cycles. • SiO 2 - P -SO 3 Na enables selective Sr(II) capture from simulated waste streams and natural seawater. • The adsorption mechanism of Sr(II) by SiO 2 - P -SO 3 Na mainly involves cation exchange. Selective removal of radioactive 90 Sr from groundwater and seawater is challenging due to its long half-life, high toxicity, and chemical similarity to other alkali/alkaline earth metal ions. Herein, a silica-based sulfonic acid-functionalized resin (SiO 2 - P -SO 3 Na) with mesoporous architecture, high surface area, and good chemical stability is engineered for Sr (II) capture. It exhibits strong Sr (II) affinity over a broad pH range (1–7). Batch adsorption tests (initial Sr (II) concentration: 20–700 mg/L) showed a maximum capacity of 57.56 mg/g. At an initial concentration of 50 mg/L, the removal rate reached 99.9%, equilibrium was reached within 1 min, and the distribution coefficient ( K d ) was 2.28 × 10 7  mL/g. Dilute HCl enabled quantitative Sr (II) recovery, and >99% removal efficiency was maintained after six cycles. The resin effectively captured Sr (II) even in the presence of competing cations and in real seawater. Continuous-flow column experiments confirmed stable operation, and characterization indicated cation exchange as the primary mechanism. This work provides a robust platform for efficient trace radiostrontium removal in environmental radioactive decontamination. Download: Download high-res image (181KB) Download: Download full-size image