A Flow-System Comparison of the Reactivities of Calcium Superoxide and Potassium Superoxide with Carbon Dioxide and Water Vapor 820873

Superoxides can be used in self-contained, emergency self-rescuers, both as sources of chemically stored oxygen and as carbon dioxide scrubbers. In the work described here, a single-pass flow-system test facility was employed to evaluate the reactivity of calcium superoxide, Ca(O₂)₂, with respiratory gases (H₂O,CO₂), in concentrations simulating exhaled breath. When compared with commercial preparations of potassium superoxide, KO₂, 55–60% Ca(O₂)₂ was found to evolve oxygen and absorb carbon dioxide at significantly lower rates under conditions where each of the superoxides was reacted with 5% CO₂ streams having dew points of 37°C. Whereas O₂ evolution and CO₂ absorption occurred simultaneously in the case of KO₂ beds, CO₂ absorption lagged O₂ evolution when beds of Ca(O₂)₂ were reacted with moisture and CO₂. It is postulated that hydration of the calcium hydroxide, Ca(OH)₂, and calcium peroxide, CaO₂, formed as a product of the Ca(O₂)₂ − H₂O reaction, is necessary to the reactivity of Ca(O₂)₂ preparations with CO₂.