Selection of Scheme for Impregnation of Sodium Titanate onto Ion-Exchange Fibers for Radioactive Strontium Removal from Seawater

Abstract

For the removal of radioactive strontium dissolved in seawater in the harbor near the Fukushima Daiichi Nuclear Power Plant, two kinds of sodium-titanate (ST) -impregnated fiber were prepared by means of radiation-induced graft polymerization and subsequent chemical modifications: one was ST-impregnated fiber, or SSS-ST fiber, originating from cation-exchange fiber that was prepared by grafting sodium styrene sulfonate (SSS) onto a 6-nylon fiber, and the other was DMAEMA-ST fiber originating from anion-exchange fiber prepared by grafting dimethylaminoethyl methacrylate (DMAEMA) onto 6-nylon fiber. In a batch adsorption mode, these ST-impregnated fibers exhibited a higher removal rate of strontium in seawater than commercially available ST adsorbent (SrTreat) in a granulous form. At a mass ratio of seawater to fiber of 100, the percentages for the removal of strontium were 86 ％ and 83 ％ for the SSS-ST and DMAEMA fibers, respectively. From the viewpoint of endurance against alkaline conditions in the preparation scheme, the SSS-ST fiber was judged to be feasible for practical use.