Synergistic enhancement of iodine capture from humid streams by microporosity and hydrophobicity of activated carbon fiber

Activated carbon fibers (ACF) are widely used to remove gaseous radioiodine produced during spent fuel reprocessing owing to their excellent adsorption properties. However, ACF's strong affinity for moisture tends to dominate, significantly reducing its ability to capture iodine in humid environments. The study used a one-step facile modification method of spray-deposited poly(divinylbenzene) (PDVB) nanoparticles on ACF to prepare hydrophobic activated carbon fiber (ACF-PDVB1.5). Compared to the initial ACF, the ACF-PDVB1.5 enhances the specific surface area to 1571 m2/g while maintaining abundant active sites, overcoming the disadvantage of pore reduction caused by traditional modification methods. More importantly, they also have excellent acid and alkali resistance and hydrophobicity (water contact angle 131.1°), with a preference for I2 pores (97% microporosity). The iodine capture capacity of ACF PDVB 1.5 showed a significant increase compared to the initial ACF, as indicated by both static and dynamic adsorption tests. Notably, the dynamic iodine adsorption capacity of ACF-PDVB1.5 in a mixed iodine-water vapor stream at actual temperature (75 °C) and humid (50% RH) conditions was 1847.69 mg/g, an increase of 55.47% over the capacity of initial ACF (1188.71 mg/g). This work improves the overall I2 adsorption performance through hydrophobicity and pore size coordination.