Properties of calcium peroxide for release of hydrogen peroxide and oxygen: A kinetics study

Calcium peroxide (CaO 2 ), as one of the solid peroxides, has been increasingly used in contaminated site remediation due to its ability to release oxygen (O 2 ) and hydrogen peroxide (H 2 O 2 ). Biodegradation can be enhanced by the existence of O 2 . Hydrogen peroxide can be used to for in situ chemical oxidation via the modified Fenton . Previous studies show inconsistent results about O 2 and H 2 O 2 release during CaO 2 decomposition. Additionally, the release characteristics of O 2 and H 2 O 2 are not evaluated in detail. A series of batch experiments was conducted to investigate the properties of CaO 2 decomposition and the release kinetics of O 2 and H 2 O 2 . O 2 and H 2 O 2 were released directly from CaO 2 dissolution and H 2 O 2 was not an essential intermediate in the conversion of CaO 2 to O 2 . The two release paths formed a parallel reaction system, with a competitive relationship between the two paths. The release of H 2 O 2 and O 2 followed a pseudo-zero-order kinetics pattern and a pseudo-first-order kinetics pattern, respectively. Increasing temperature and decreasing pH could accelerate both O 2 and H 2 O 2 release rate. However, increasing temperature could decrease the H 2 O 2 yield and increase the O 2 yield, which were similar to the impact of increasing pH.