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New, highly specific and sensitive analytical methodology has been applied to the determination of chlorinated dibenzo- p -dioxins in particulate matter. The results show that the dioxins are present in particles from many types of combustion sources and in dust and soil in the vicinity of combustion sources. The data indicate that chlorinated dioxins may occur in particulate matter from the combustion of most types of organic material, and suggest the hypothesis that chlorinated dioxins result from trace chemical reactions occurring in fire.

Infrared investigations of the adsorption of the Ci through C4 normal alcohols on the surface of 7-alumina in the temperature range from 25 to 500°are described. Three different surface species are observed: physically adsorbed alcohol (I), an alkoxide-like chemisorbed surface species (II), and a carboxylate-like chemisorbed surface species (III), in agreement with previous work by Greenler.2 Mechanisms for these adsorption processes are proposed and supported with mass spectral data.

The adsorbed species which result when magnesia is exposed to methanol or ethanol vapor are reported. Five different surface species have been identified for both methanol and ethanol. At 25°C a tightly bound layer of liquid alcohol is observed. When this is removed by heat and evacuation, another species appears which is identified as a surface methoxide in the case of methanol and ethoxide in the case of ethanol. When the magnesia sample is heated to 165°C in alcohol vapor, a formatelike surface compound is formed from methanol and an acetatelike compound from ethanol. At temperatures near 430°C, two more surface species are observed to form after the disappearance of surface formate (or acetate). They are identified as a surface methyl carbonate from methanol (ethyl carbonate from ethanol) and surface carbonate which is formed from both methanol and ethanol. Both the surface alkyl carbonate and surface carbonate are attributed to a low-temperature (<240°C) reaction between surface alkoxide and CO2 which is liberated by dicarboxylation of the surface carboxylate. The interpretation of surface structures has been checked by using CD3 methanol and 13C enriched methanol. Proposed mechanisms for the formation of the different surface species (followed by mass spectrometry) are discussed.

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