Engineered Gold Nanoparticle-Functionalized Polymeric Membranes for Enhanced Radioiodine Capture: Performance, Kinetics, and Chemical Robustness

Effective removal of radioactive iodide from aqueous media is essential for addressing environmental and public health concerns associated with unintended nuclear reactor accidents, medical waste, and industrial processes. In this study, cellulose acetate (CA) and poly(vinylidene fluoride) (PVDF) membranes functionalized with gold nanoparticles (AuNPs) were systematically evaluated for radioactive iodide capture performance under varying chemical conditions. Both Au-CA and Au-PVDF membranes exhibited high iodide adsorption capacities, particularly under acidic conditions (maximum adsorption capacities: 25.97 mg/g and 26.25 mg/g, respectively), driven by enhanced surface protonation and reduced electrostatic repulsion. Adsorption kinetics closely followed a pseudo-second-order model, confirming chemisorption as the primary mechanism. Continuous-flow experiments demonstrated rapid adsorption kinetics and high removal efficiencies (> 99.5%) at extremely low iodide concentrations (~ 2.11 × 10⁻¹¹ M) within short contact times (~ 10 s). Single-photon emission computed tomography (SPECT) imaging using [¹²³I]NaI visually confirmed efficient iodide capture under realistic operational conditions. Furthermore, chemical stability assessments revealed Au-PVDF membranes to be notably robust against organic solvents, whereas Au-CA membranes showed enhanced stability in strongly basic environments. This study provides fundamental insights into adsorption behaviors and demonstrates the strong potential of AuNP-functionalized polymeric membranes for rapid, effective radioactive iodine remediation.