TITLE:
An Amidoximated-UHMEPE Fiber for Selective and High Efficient Removal of Uranyl and Thorium from Acid Aqueous Solution
AUTHORS:
Chan Jin, Jiangtao Hu, Jianqiang Wang, Chunyun Xie, Yajun Tong, Linjuan Zhang, Jing Zhou, Xiaojing Guo, Guozhong Wu
KEYWORDS:
UHMWPE Fiber, Uranium Ions, Thorium Ions, Selective Absorption Mechanism, XAFS, SR-FTIR
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.7 No.1,
December
30,
2016
ABSTRACT: High
efficient removal and recovery of uranium and thorium from nuclear waste solution
are essential for environmental preservation and fuel recycle. A new polymer
fiber adsorbent (UHMEPE-g-PAO fiber),
prepared by amidoximation of grafted polyacrylonitrile onto Ultra High
Molecular Weight Polyethylene (UHMWPE) fiber, was used to remove the uranyl and
thorium ions from acid aqueous solutions and its performance was carefully
investigated. It was found that uranyl ion can penetrate the fiber through the
connected pore structures, forming (UO2) (R-C(NH2)-NO)2 chelates with
the amidoxime groups within the fiber. Two amidoxime groups (U-N and U-Oeq)
and two water molecules (U-Oeq2) are bound to uranyl ion in the fiber. On the contrary, thorium ions
are adsorbed mainly on the fiber surface in the form of Th(OH)4 precipitate
that blocks the entrance of Th4+ ion into fiber pores. The maximum included
other two capacities of uranyl and thorium ions were estimated to be 262.01 mg/g
and 160 mg/g at room temperature with pH 3.0, respectively. The results also
indicate that the UHMWPE-g-PAO fiber has
higher adsorption selectivity for uranyl ion than thorium ion. Uranium and
thorium oxide particles were obtained as the ultimate product after sintering
of the fiber adsorbent. This novel and environmentally friendly adsorption process is feasible to extract
uranium or thorium from acidic aqueous solution.