Surface modification of polypropylene non-woven filter by O₂ plasma/acrylic acid enhancing Prussian blue immobilization for aqueous cesium adsorption

Radioactive cesium is commonly emitted during nuclear accidents and Prussian blue (PB) is an effective adsorbent with superior selectivity toward cesium. This study describes the surface modification of a polypropylene non-woven filter (PP) as the supporting material for PB immobilization, which included O₂ plasma treatment and acrylic acid (AA) modification. AA was successfully polymerized using O₂ plasma to provide a reaction site for the polymerization. The carboxylic acid groups introduced by the polymerization of AA induced a higher amount of PB immobilization on the surface. The cesium adsorption performance of the prepared adsorbent filter was evaluated via adsorption kinetics and isotherm analyses. The maximum adsorption capacity was calculated as 51.9 mg/g according to the Langmuir isotherm. To confirm its long-term practical applicability, the adsorbent filter was incorporated into a flow-through water treatment system that was operated for three months. The tested five-layer filter achieved a 100% cesium removal efficiency (initial concentration 40 μg/L) during the first 12 days, after which a 50% removal efficiency was maintained for 24 days. Therefore, the surface modification methodology proposed herein provides a promising means to convert commercial filter materials into advanced water treatment filters for the removal of radioactive cesium from contaminated water.