DC corona electric discharges for air pollution control. 2. Ionic intermediates and mechanisms of hydrocarbon processing

A mechanistic study is reported on i-octane and hexane processing with +DC and -DC corona in air at room temperature and pressure. Current/voltage profiles are matched with the ion analysis data obtained by APCI mass spectrometry. With a -DC corona, the hydrocarbons do not modify the negative ion population with respect to uncontaminated air. In contrast, with a +DC corona many hydrocarbon-derived positive ions form. 0(P-3) and (OH)-O-center dot were also investigated using chemical probes (ozone formation and CO oxidation, respectively). The results, combined with efficiency and product data, suggest that with -DC corona radical initiation steps occur, whereas with +DC corona ionic reactions prevail.