Innovative seawater uranium recovery agent based on low-cost polyacrylonitrile fibers

Doonyapong Wongsawaeng; Wijittra Wongjaikham; Deni Swantomo; Kris Tri Basuki

doi:10.1016/j.apradiso.2020.109067

Innovative seawater uranium recovery agent based on low-cost polyacrylonitrile fibers

Appl Radiat Isot. 2020 Apr:158:109067. doi: 10.1016/j.apradiso.2020.109067. Epub 2020 Jan 31.

Authors

Doonyapong Wongsawaeng¹, Wijittra Wongjaikham², Deni Swantomo³, Kris Tri Basuki³

Affiliations

¹ Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, 10330, Thailand. Electronic address: Doonyapong.w@chula.ac.th.
² Department of Nuclear Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok, 10330, Thailand.
³ Polytechnic Institute of Nuclear Technology, National Nuclear Energy Agency Jl. Babarsari Kotak Pos 6101 YKBB, Yogyakarta, 55281, Indonesia.

PMID: 32174380
DOI: 10.1016/j.apradiso.2020.109067

Abstract

An innovative seawater uranium adsorbent was prepared from the low-cost and commercially-available polyacrylonitrile (PAN) fibers. The optimum condition to synthesize the adsorbent was to irradiate the PAN fibers with 100 kGy gamma ray, amidoximate in 3 (w/v)% hydroxylamine hydrochloride solution for 75 min at 75 °C, yielding the PAN nitrile group conversion of approximately 60%. At 100 kGy, the degree of crystallinity of the irradiated fibers was also highest at 79.1%. The performances of the adsorbent in seawater samples were excellent. By submersion in the seawater sample spiked with 250 ppb of uranium for 4 weeks, the prepared fibers exhibited the adsorption capacity of 32.28 mg/g adsorbent. By submersion in seawater samples spiked with 76.5 ppm of uranium for 1 week and 945 ppm of uranium for up to 4 weeks, the fibers exhibited the adsorption capacities of 111.25 and 200.07 mg/g adsorbent, respectively. The adsorbent showed a uranium adsorption capacity of 0.11 mg/g adsorbent for 8 weeks of soaking in brine concentrate from a seawater reverse osmosis plant. The kinetics of seawater absorption by the adsorbent was quite rapid, reaching the equilibrium swelling ratio of approximately 300% in 5 min or less. Another important finding was that the prepared PAN fibers exhibit the characteristics of a superabsorbent material (equilibrium swelling ratio in DI water of 5,550%). The low cost and the ease of preparation of the fibers offer a novel environmental remediation process to adsorb uranium ions released into seawater following a nuclear accident.

Keywords: Amidoxime functional group; Gamma ray; Polyacrylonitrile (PAN) fiber; Seawater; Uranium recovery.