Efficient removal of radioactive iodide from contaminated seawater by radiation-resistant Ag+-doping polypropylene nonwoven adsorbents

Abstract

For the efficient removal of radioactive iodide ions from medium and low radioactive contaminated water, an Ag-doped adsorbent was designed via radiation grafting method and chemical modification and applied based on the solid–liquid adsorption method. The silver loading content in the adsorbents could be flexibly decided by adjusting the sulfhydryl content. SEM/EDS, ATR, XPS, and XRD characterization methods were used to determine the features of the new adsorbents. With the silver content 67.9 mg/g and 125.6 mg/g in the adsorbents PGM25%-Ag+ and PGM220%-Ag+ respectively, the maximum I− adsorption capacities were varied at 29.92 mg/g and 100.82 mg/g. In wide pH conditions (pH7-11), PGM25%-Ag+ was sufficient to achieve 131I removal efficiency of over 92 %, and the removal efficiency was almost unaffected in the coexistence of high concentration (10 mmol/L) of anions and complex real contaminated seawater, highlighting the applicability and selectivity of the adsorbent. The adsorption behavior conformed to the Langmuir isothermal model and pseudo-second-order kinetics model. XPS analysis confirmed that excellent adsorption capacity and selectivity were attributed to the chemical adsorption mechanism of ion exchange and complexation occurs between I− and Ag on the solid–liquid interface, where AgI precipitation formed. In addition, the Ag+-doping adsorbent withstood the harsh conditions of 200 kGy irradiation by observing the ATR structure, thermal stability, and 131I removal property. This study provides a feasible solution for the treatment of low and medium-radioactive contaminated seawater.