作者：YASUO NAKAMURA;KAZUHIKO HAMAGUCHI;WATARU SHIRATO;

作者单位：Mitsubishi Nuclear Fuel Co., Ltd., 622-1, Funaishikawa, Tokai-mura, Naka-gun, Ibaraki-ken, 319-1197

刊名：Taikabutsu Overseas

ISSN：0285-0028

出版年：2002-01-05

卷：22

期：2

起页：80

止页：85

分类号：TQ175

语种：英文

关键词：

内容简介

We developed a process using tannin gel to remove and recover hexavalent chromium Cr(VI) dissolving out of used magnesia-chrome brick. The tannin gel was produced through gelation of molecules of wattle tannin, a natural tannin that contains many polyhydroxyphenyl groups, with formaldehyde acting as a cross-linking agent. The tannin gel was used as an adsorbent to remove Cr (VT) from waste water in which 116 mg/L Cr(VI), 159 mg/L Mg(II) and 37 mg/L Na(I) originating from used magnesia-chrome brick had dissolved. The adsorption of Cr(VI) proceeded through the reduction of Cr(VI) to Cr(III), the formation of carboxyl groups by the oxidation of tannin molecules which occurred in parallel to the reduction of Cr(VI) and the ion exchange of the reduced Cr(III) with carboxyl and the hydroxyl groups. The adsorption process was controlled by adjusting the pH in the waste water; the pH was adjusted first to pH=3 to adsorb Cr(VI) and then to pH=6.0 to fix the reduced Cr(III) inside the tannin gel. By this process, the concentration of Cr(VI) could be reduced below the environmental discharge regulation level of 0.05 mg/L, and the total chromium (Cr (VI) and Cr(III)) concentration could also be reduced to less than the regulation level of 2.0 mg/L.