Catalytic Generation of Chlorine Dioxide from Chlorite Using a Water-Soluble Manganese Porphyrin

摘要

The industrial preparation of chlorine dioxide (ClO2) is energy-intensive and fraught with health and safety issues. Furthermore, due to the instability of ClO2 at high pressures, the gas must be generated at the point of use. ClO2 is an oxidizing agent employed as an alternative to chlorine in paper bleaching, pathogen decontamination and water treatment due to its superior antimicrobial properties and reduced tendency to produce harmful organochlorine by-products. The large-scale production of ClO2 involves the use of concentrated acids and/or externally added oxidants (such as Cl2, H2O2, or hypochlorite). Electrochemical methods can directly oxidize ClO_2~- to ClO2 by a one-electron process but these require considerable input of electrical energy and may not be applicable in rural or underdeveloped areas of the world. An iron-catalyzed decomposition of ClO_2~- has been shown to afford ClO2 (in part), but only under very acidic conditions. Accordingly, these hazardous and/or costly methods must be implemented in facilities that are primarily engineered for other purposes.