Detoxification or decontamination of effluents and/or flue gases

Abstract From the Canadian patent

This invention provides a process for detoxifying or decontaminating liquid effluents and/or waste gas containing poisonous chromium (VI) NOx by reacting these with each other with formation of chromium (III) and higher oxide(s) of N. Optionally in addition another suitable reducing agent may be used. The process is particularly useful for example, in, a plant such as a stainless steel pickling plant where both these chemical components are available. Preferably liquid-liquid extraction may be used to extract and recover nitric acid formed as an oxidation product and preferably if additional chromium (VI) is required this may be provided by electrolytic oxidation of chromium (III) to …