Retention of simulated strontium in a permeable reactive barrier: a full factorial design approach with natural sorbents

Environmental contamination caused by the release of long-lived radionuclides, particularly strontium-90 (half-life: 28.1 years), presents significant ecological and public health risks. This study investigates the performance of a multilayer permeable reactive barrier (PRB) system composed of locally sourced, low-cost natural sorbents—zeolite, clay, diatomite, and sepiolite—for Sr(II) immobilization under simulated nuclear accident conditions. A comprehensive two-level full factorial design (2⁵) was implemented to evaluate the effects of pH, particle size, bed volume, flow rate, and initial concentration on Sr(II) uptake. Each material was characterized using SEM–EDX, XRD, Gas adsorption, FTIR, and EDXRF. Sorption efficiency was quantified through continuous-flow column experiments supported by ICP-OES and EDXRF measurements. Statistical modeling via regression and ANOVA revealed significant individual and interaction effects, particularly involving pH, particle size, and bed volume. The optimized PRB configuration achieved over 92% removal efficiency. Despite the use of stable Sr-88, the findings offer scalable design insights for strontium retention in nuclear emergency scenarios. This work presents an original contribution to sustainable in-situ remediation technologies.