Control effects of pε and pH on the generation and stability of chlorine dioxide

摘要

A new method, without assistance of activity ratio diagram, was applied to construct the p ε |pH diagrams for chlorine system. The optimal pH range for generation of ClO 2 by contacting Cl 2(g) directly with ClO - 2 solution is within pH 1 35—1 94, particularly within pH 1 35—4 00 only if minimizing the formation of Cl 2 It is unachievable to synthesize pure ClO 2 from the reaction of Cl 2 and ClO - 2. Conversely, ClO 2 may be present a variation of stability in different waters owing to the changed p ε and pH. ClO 2 could be relatively stable if not disproportionate into ClO - 3, coexisting with ClO - 2 (p ε 17 63 and pH>9 68), Cl 2 (pH≤0 92) or Cl - (pH 0 92—9 68). When chlorine system has already reached the ultimate equilibria, ClO 2 is a stable species in strongly acid media. As the acidity decreases, ClO 2 disproportionates into ClO - 3 and Cl 2 Aqueous ClO 2 is unstable within the normal pH range. This work initially, theoretically elucidates the generation and stability of ClO 2 by way of the p ε pH diagrams.