Quantification and risk assessment of organic products resulting from non-thermal plasma removal of toluene in nitrogen

Rationale: Non-thermal plasma (NTP) has proven to be an effective approach for the removal of volatile organic compounds (VOCs). However, harmful organic by-products, produced during NTP-mediated removal of VOCs, hinder practical applications of this technology. It is necessary to characterize the organic by-products to assess their health risks. Methods: A method is proposed for analyzing and evaluating organic by-products for NTP-mediated removal of VOCs in this work. NTP generated by a coaxial dielectric barrier discharge (DBD) reactor was used for the removal of a model VOC, toluene, in nitrogen. Organic products were characterized using a real-time proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) apparatus. Results: The PTR-TOF-MS apparatus has been shown to be effective for real-time high-sensitivity detection of trace VOCs. The main observed organic compounds, with concentrations on the order of ppb/ppm, were hydrogen cyanide, acetonitrile, propanenitrile, benzene, benzonitrile, and benzyl nitrile, etc. Conclusions: A health-related index (HRI) was introduced to assess the health risks associated with these organic products. The HRI was not correlated with the removal efficiency (eta), with higher. possibly yielding higher HRI, associated with higher health risks. Specific input energy (SIE) was a key factor affecting the formation of the observed organic products and their HRI values. We conclude that in practical applications, SIE, HRI, and. must be balanced.