Recycling Sulfochromic Solutions after a Surface Treatment

Abstract

Sulfochromic solutions are still widely used for surface treatments. Unfortunately resulting effluents are strongly polluting. Requirements for environmental protection become tougher and tougher. Each type of effluent requires a specific treatment. The effluent we are working upon comes from the surface treatment of oily rivets produced by machine tools and used in plane industry. It is characterized by important concentrations in chromium as well as in sulfuric acid. The purpose of this work is to use lead oxidizing properties and electrodialysis process to reoxidize Cr(III) in order to obtain cleaner effluents which can then be recycled.