Corrosion of stainless steels in chlorine dioxide solution

Until recently, chlorine used to be an important chemical in bleaching process in paper industry, but as a result of environmental concerns, it is being replaced by chlorine dioxide. However, chlorine dioxide is more corrosive in certain conditions. Plant personnel, therefore need to better understand the reactions taking place in the changed media and search for more resistant materials. It is with this in mind that the present work was undertaken. The paper reports the electrochemical polarisation measurements performed on stainless steels 316L, 317L, 2205 and 254SMO in chlorine dioxide solutions to observe localised corrosion. The results have been analysed with reference to Pourbaix diagrams, taking into account the various chemical species present in the bleach solutions. Conclusions drawn from electrochemical tests have been compared with those from long-term laboratory and plant tests. Materials options are proposed on the optimal choice of materials for bleach plants, in a context of probable corrosion performance, capital cost and mechanical strength.