抄録
Among methods of handling waste which contains toxic heavy metals, fixation in concrete has gained broad acceptance and is commonly used. If waste containing highly toxic hexavalent chromium is to be fixed using normal portland-type cement, the possibility of secondary contamination should be eliminated by preventing any elution of hexavalent chromium from the hardened paste over a long period of time. Thus it appears that simply using concrete is inadequate.
We turned their attention to a chemical reaction that occurs when hexavalent chromium reacts with barium ions in an alkalescent domain. The reaction generates barium chromate, which is insoluble. Thus barium chloride was added to high-early-strength portland cement and the material was used to fix hexavalent chromium. This paper reports on that process because it was proved that the material can fix waste which contains hexavalent chromium for a long time.
Using X-ray diffraction and SEM (scanning electron microscopy), it was confirmed that the fixing mechanism is a consequence of the generation of insoluble barium chromate.
Today many fields are creating demand for the stable fixation of waste which contains hexavalent chromium. We believe that treatment using the fixation material described here is highly effective.
