Atomization efficiencies in halocarbon-loaded acetylene-air flames—I. Monochlorides of readily volatilized elements

Abstract

Carbon tetrachloride vapour was introduced with a carrier air stream into the mixing chamber of an acetylene-air flame while nebulizing aqueous solutions of several metal salts. The atomic absorption signal was measured under increasing flow rate of the halocarbon vapour at constant fuel-to-oxidant ratio, and the latter parameter was also varied in separate experiments. By applying the theory developed by Sugden and Bulewicz, the exclusive formation of monochlorides in the gaseous phase (presented here, in Part I) and the additional formation of hydroxychlorides and dichlorides (presented in Part II) could be elucidated. From the decrease of the signal measured for the alkali elements of known monochloride dissociation constants and dissociation energies, the temperature and the chlorine concentration present in the observed flame zone could be calculated. It is inferred that only 19% of the total halogen introduced is converted to HCl and Cl species in a slightly fuel-rich flame. The signal depression is stronger in a fuel-lean flame of higher monoatomic chlorine concentration for those elements which have a relatively efficient atomization under these flame conditions. An increase of the electron concentration resulting from the introduction of the halocarbon in an alkali-containing flame was deduced from the experimental findings, in agreement with earlier observations.