Study on selective electrosorption of thorium by carbon material containing aminophosphonate functional group
To separate and remove trace thorium from rare earths,a carbon electrode material(CNT-P)was prepared by modi-fying aminated carbon nanotubes(CNT-N)with phosphonate.The morphology,composition and electrochemical properties of CNT-P were analyzed by scanning electron microscope(SEM),surface area analyzer,X-ray photoelectron spectroscopy(XPS),thermogravimetric analyzer(TGA),Fourier transform infrared spectrometer(FT-IR)and electrochemical workstation.The effects of solution medium,pH,voltage and the initial thorium concentration on the adsorption of thorium were studied.The adsorption selectivity of CNT-P toward thorium and rare earths was discussed.The regenerative recycling performance of CNT-P was examined.The results indicated that CNT-P was a mesoporous and macroporous structure combined electrode material,with a BET specific surface area of 111.6 m2/g,a pore volume of 0.85 cm3/g and an average pore size of 30.13 nm.The maximum electrosorption capacity of CNT-P towards thorium reached 219 mg/g in hydrochloric acid solution.The separa-tion factors for Th/REs were higher than 10 at voltage of 3.5 V.After 5 cycles of adsorption-desorption,the adsorption capac-ity of CNT-P toward thorium maintained 87％as compared with its initial adsorption and basically kept stable.Therefore,CNT-P showed a promising application prospect for the efficient removal of micro-trace thorium from rare earth earths.
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