Enhancement of the adsorptive property of the amidoxime group containing fiber by alkaline treatment

To improve the uranium adsorption rate of the fibrous adsorbent (AO-fiber), the alkaline treatment of the AO-fiber (A-AO-fiber) was investigated. As increasing duration of alkaline treatment, the content of weak acidic group increased whereas that of weak basic group remained constant. IR spectra of the A-AO-fiber showed the decrease of cyano group whereas the increase of carboxyl group. The adsorption capacity of Cu(2) and the adsorption rate of uranium of the A-AO-fiber increased with increasing the duration of alkaline treatment. The A-AO-fiber after alkaline treatment for 48 h adsorbed about 2 mg-U/g-fiber in a week from sea water. On the other hand, the single fiber strength of the A-AO-fiber became weaker by alkaline treatment, and the A-AO-fiber after alkaline treatment for 48 h showed about a half of the strength of the AO-fiber. About 90 % and 100 % of uranium was eluted by 0.1 mol/1 HC1 solution from the fibrous adsorbent in 15 min and in 2 h respectively. The A-AO-fiber could be reused for adsorption and desorption of uranium from sea water without any significant decrease in the adsorption rate. (author)