Indoor air quality improvement and purification by atmospheric pressure Non-Thermal Plasma (NTP)

Non-thermal plasma (NTP) is a promising technology for the improvement of indoor air quality (IAQ) by removing volatile organic compounds (VOCs) through advanced oxidation process (AOP). In this paper, authors developed a laboratory scale dielectric barrier discharge (DBD) reactor which generates atmospheric NTP to study the removal of low-concentration formaldehyde (HCHO), a typical indoor air VOC in the built environment associated with cancer and leukemia, under different processing conditions. Strong ionization NTP was generated between the DBD electrodes by a pulse power zero-voltage switching flyback transformer (ZVS-FBT), which caused ionization of air molecules leading to active species formation to convert HCHO into carbon dioxide (CO2) and water vapor (H2O). The impact of key electrical and physical processing parameters i.e. discharge power (P), initial concentration (C-in), flow rate (F), and relative humidity (RH) which affect the formaldehyde removal efficiency were studied to determine optimum conditions. Results show that, the correlation coefficient (R-2) of removal efficiency dependence on the processing parameters follow the order R-2 (F) = 0.99 > R-2 (RH) = 0.96, > R-2 (C-in) = 0.94 > R-2 (P) = 0.93. The removal efficiency reached 99% under the optimum conditions of P = 0.6 W, C-in = 0.1 ppm, F = 0.2 m(3)/h, and RH = 65% with no secondary pollution. The study provided a theoretical and experimental basis for the application of DBD plasma for air purification in the built environment.