| 摘要 |
PROBLEM TO BE SOLVED: To reduce hexavalent chromium in a neutral to alkali region while simultaneously to flocculate and precipitate trivalent chromium to separate from a soln. and to prevent new contamination due to the added material without requiring pH control during the treatment by introducing silicon into the environment contaminated with hexavalent chromium. SOLUTION: In order to treat hexavalent chromium in the environment contaminated with hexavalent chromium, silicon is introduced into the environment. As for the silicon, various states of silicon can be used and particulate silicon is preferable considering its reactivity. By this treating method, flocculation of trivalent chromium produced by the reduction with silicon is simultaneously caused, which prevents leaching of trivalent chromium. The flocculated precipitate produced in the water containing hexavalent chromium has excellent transparency so that it can be easily separated by filtration. Moreover, the precipitate has effects to form silanol groups in the reaction process and to adsorb other heavy metal ions to the silicon surface. The flocculated precipitate has a large silicon component and is regarded as a waste material suitable for solidification of glass and cement. |
