Electrolytic control of hydrogen peroxide release from calcium peroxide in aqueous solution

The in situ generation of hydrogen peroxide (H₂O₂) for water treatment is more practical than the use of liquid H₂O₂, which is costly to store and transport. Calcium peroxide (CaO₂), a solid carrier of H₂O₂, can release H₂O₂ on dissolution in water. However, the constant H₂O₂ release rate of CaO₂ has been a bottleneck constraining its wider application. In this study, a practical electrochemical method using a divided cell is developed to control the rate of release of H₂O₂ from CaO₂. The results show that the rate of H₂O₂ release from CaO₂ is enhanced in the anolyte. The increase in H₂O₂ release is positively correlated with the current. Under a current of 100 mA, the H₂O₂ concentration was 2.5 times higher after 30 min of electrolysis than in the control experiment in which no current was applied. Water electrolysis in the anodic compartment generates protons that not only: (i) en-hance dissolution of CaO₂ and release of H₂O₂, but also (ii) neutralize the alkaline pH resulting from CaO₂ dissolution, thus providing new advantages for the use of CaO₂. This effective technique may be suitable for the sophisticated control of H₂O₂ release in environmental applications.