Radioactive strontium removal from seawater and groundwater with adsorptive fibers prepared by radiation-induced graft polymerization

Shun Ichi Goto, Michitaka Kono, Shigeko Kawai-Noma, Daisuke Umeno, Kyoichi Saito, Kunio Fujiwara, Takanobu Sugo, Takahiro Kikuchi, Yasutomi Morimoto, Takahito Miki

Research output: Contribution to conferencePaperpeer-review

Abstract

The Great East Japan Earthquake and the tsunami that followed caused the meltdown of three reactors of the TEPCO Fukushima Daiichi nuclear power station (NPS), resulting in the emission of radionuclides such as cesium-137 and strontium-90 to the environment. Radioactive strontium was detected in seawater and groundwater at concentrations of 1.8 × 102 and 5.5 × 105 Bq/L, respectively, on October 7th 2014 [1]. Nonradioactive strontium dissolves at a concentration of 8 mg/L in seawater. No adsorbent can distinguish radioactive strontium from nonradioactive strontium; therefore, the adsorbent must collect both ions which coexist with other alkaline-earth metal ions such as magnesium and calcium ions. Inorganic compounds and chelate-forming resins are candidate adsorbents for strontium removal [2, 3]. However, It is difficult to use these adsorbents to process a large volume of water contaminated with radionuclides because of their granule and bead forms. We have prepared two kinds of adsorptive fiber by radiation-induced graft polymerization and subsequent chemical modifications: (1) sodium-titanate-impregnated fiber (ST fiber) [4-7] and (2) iminodiacetate-group-immobilized fiber (IDA fiber)[4]. The preparation scheme of the ST fiber consisted of four steps. First, a commercially available 6-nylon fiber was irradiated with γ-rays to produce radicals. Second, sodium styrene sulfate was graft-polymerized onto the irradiated fiber. Third, a titanium species [Ti(OH)22+]was bound to the sulfonic acid group of the grafted polymer chain. Finally, the titanium species was converted into sodium titanate with sodium hydroxide, and the resulting precipitate was impregnated onto the fiber. On the other hand, the IDA fiber was prepared as follows. An epoxy-group-containing vinyl monomer, glycidyl methacrylate, was graft-polymerized onto a previously γ-ray-irradiated 6-nylon fiber. Subsequently, the epoxy group was converted into an iminodiacetate group as a chelate-forming group by a reaction with disodium iminodiacetate. The former and latter fibers are applicable to strontium removal from seawater and groundwater, respectively.

Original languageEnglish
Publication statusPublished - 2015
Externally publishedYes
Event23rd International Conference on Nuclear Engineering: Nuclear Power - Reliable Global Energy, ICONE 2015 - Chiba, Japan
Duration: 2015 May 172015 May 21

Conference

Conference23rd International Conference on Nuclear Engineering: Nuclear Power - Reliable Global Energy, ICONE 2015
CountryJapan
CityChiba
Period15/5/1715/5/21

Keywords

  • Adsorptiove fiber
  • Iminodiacetate group
  • Radiation-induced graft polymerization
  • Sodium titanate
  • Strontium removal

ASJC Scopus subject areas

  • Nuclear Energy and Engineering

Fingerprint Dive into the research topics of 'Radioactive strontium removal from seawater and groundwater with adsorptive fibers prepared by radiation-induced graft polymerization'. Together they form a unique fingerprint.

Cite this