The effect of ionization energy and hydrogen weight fraction on the non-thermal plasma volatile organic compounds removal efficiency

Abstract

The degree of difficulty of volatile organic compounds (VOCs) degradation in non-thermal plasma (NTP) related to their chemical structures, ionization potentials and hydrogen weight fraction was investigated. Benzene, methylbenzene, xylene, n-pentane, n-hexane, cyclohexane, ethyl acetate, ethyl propionate, ethyl butyrate, propanone, 2-butanone and 2-pentanone, total 12 VOCs were chosen as the typical VOC agents from the four main types of VOCs such as aromatic hydrocarbons, alkanes, ketones and esters with different structures and ionization potentials. The experimental results indicate that the ionization potential is a parameter indicating the destruction efficiency of VOCs by NTP. It is a trend that the higher the ionization potentials are, the weaker the reactivity of VOCs and radicals, and the more difficult it is to destroy VOCs at the same initial VOC concentration and the specific input energy. The influence of hydrogen weight fraction on the decomposition efficiency is different from the ionization potential one’s. For aromatic hydrocarbons, ketones and esters, the higher removal efficiency is observed with the higher percentage of hydrogen; for alkanes, the situation is just the opposite. It is indicated that this exceptional situation relates to chemical structures of VOCs. Their chemical structures make the trend of the relation of VOCs degradation efficiency on the ionization potentials appear a deviation.