The structures of the active intermediates in Catalyst-Enhanced Molten Salt Oxidation and a new method for the complete destruction of chemical warfare arsenicals

Abstract

Catalyst-Enhanced Molten Salt Oxidation (CEMSO) is our improvement of the earlier process, Molten Salt Oxidation (MSO), originally employed for the destruction of hazardous materials by high temperature oxidation in a carbonate melt. MSO was abandoned because it was slow and only partially oxidized cotton, paper, and plastics. It was very efficient for many other chemicals and had oxidized the nerve gas sarin with >99.9999% efficiency. We came to realize that the concentration of the oxidizing species, superoxide and peroxide ions, produced from the oxygen entering the carbonate melt, could be increased and maintained by the addition of nitrate ions as catalyst. The structure and interatomic distances for the various possible adducts between nitrate and nitrite with oxygen and peroxide have been calculated for the first time by Density Functional Theory (DFT). Their calculated enthalpies, as a function of temperature, revealed which adducts can be formed in the carbonate melt. The Japanese still have large stocks of the chemical warfare arsenicals Clark I and Clark II awaiting a destruction procedure that ensures removal of all volatile As(III) compounds. We have established that As(V) salts are stable at high temperature and here discuss how CEMSO can efficiently achieve this for the Clark arsenicals.