The selective removal of 137Cs ions from liquid radioactive waste and their quantitative determination in the environment have a great importance in recent years. Insoluble divalent transition metal hexacyanoferrates(II) are very effective inorganic adsorbents for cesium ions . Because they possess a high selectivity for Cs binding in the presence of alkaline earth and alkali metal ions, several attempts have been made to use hexacyanoferrates (HCFs) for the treatment of liquid radioactive waste with high salt content [2, 3].
However, HCFs are usually synthesized as fine or ultrafine grains which are difficult for practical applications due to their low mechanical stability and tendency to become colloidal in aqueous solution. In order to improve their mechanical properties, deposition of insoluble hexacyanoferrates on various solid supports has been suggested as a possible solution. Different composite adsorbents were fabricated by loading nanosized HCFs onto the surface or inside of pores of inert solid supports such as silica gels , zeolites , zirconium and titanium hydroxides , different organic ion exchangers [7, 8], etc.
Fibrous natural and synthetic polymers with ion exchange groups are promising host solid support for the synthesis of composite adsorbent with nanosized HCFs. Such composite adsorbent is expected to combine the unique properties of nanoscaled HCF particles (high specific surface, high speed of chemical reactions, selectivity) and technological properties of fibrous polymer matrix (flexibility, chemical stability, high specific surface, low hydraulic permeability, and ease utilization in dynamic sorption regimes).
Among various hexacyanoferrates, one of the most promising cesium-selective reagents is potassium nickel hexacyanoferrate (KNiHFC), which displays high chemical resistance in acid and alkaline solutions, mechanical stability, and thermal stability [2, 9]. Polypropylene (PP) fibers and nonwoven fabrics are very attractive support in preparing nanocomposite adsorbents because of the low cost, good mechanical strength, chemical and thermal resistance of the PP base, and highly developed specific surface of the fibrous structure.
In this study we propose a novel nanocomposite adsorbent based on a KNiHCF-loaded polypropylene fabric for Cs, which was prepared by the radiation-induced graft polymerization of acrylic acid monomer onto the surface of nonwoven polypropylene fabric, followed by in situ formation of KNiHCF nanoparticles within the grafted polyacrylic acid chains. The synthesized adsorbent was used for the removal of Cs ions from the model solutions in batch mode, and the influence of contact time, pH, and presence of sodium ions on the adsorption process was investigated.