水酸化クロムおよび含クロム混合水酸化物の焼成における6価クロム生成

概要

論文の詳細を見る
Waste sludge from surface finishing industries generally contains a large amount of water. It is proposed that calcination will be a simple and convenient method for reducing the volume and weight of the sludge. However, when the sludge contains chromium, some amount of chromium in the sludge can be converted to the harmful hexavalent state during the calcining operation. In this study, the generation of hexavalent chromium in the calcination of chromium hydroxide reagent was compared with that of a sludge obtained from an actual industry. In both cases of the chromium hydroxide and the sludge, the amounts of hexavalent chromium leached from the samples became higher with an increase of heating temperature when their structures were in the amorphous state, and then the amounts of hexavalent chromium lowered after their crystallization. Calcinations of the mixtures of chromium hydroxide and one of the other hydroxides of nickel, copper, zinc, or ferric iron were attempted, but none of them could lower the hexavalent chromium at 700ºC to the level of the sludge tested in this study. However, when these hydroxides were mixed in the ratio similar to that of the sludge, the amount of hexavalent chromium leached from the sample became as low level as that of the sludge.
一般社団法人表面技術協会の論文
2006-06-01