Wet-Type Packed-Bed Nonthermal Plasma for Simultaneous Removal of PM and VOCs

Several regulations on exhaust gases have been introduced to curb hazardous exhaust of volatile organic compounds (VOCs) and particulate matter (PM) from the paint and printing industries. VOCs produce photochemical oxidants and suspended PM such as PM_2.5, which is now recognized as a global environmental problem. We assess a nonthermal plasma technique for controlling VOC emissions, especially, propose a wet-type packed-bed plasma reactor to extend the treatment of water-non-soluble VOCs. This paper proposes a wet-type packed-bed plasma reactor to extend the treatment of water-non-soluble VOCs. The proposed technique is evaluated through the simultaneous removal of nanoparticles and toluene at a relatively high flow rate. Simultaneous treatment of the VOCs and nanoparticles using the reactor indicates that the average particle collection efficiency is 94%, and the removal efficiency of 60 ppm toluene is 73% with a gas flow rate of 10 L/min. The resultant byproducts are benzaldehyde (C₆H₅CHO), benzyl alcohol (C₆H₅CH₂OH), phenol (C₆H₅OH), ozone, formic acid, and acetic acid, and some are easily dissolved and removed by the sodium hydroxide solution film. A smaller pellet diameter leads to more efficient toluene removal at lower specific energy values, while the ozone concentration does not change. However, the ozone concentration can be greatly suppressed by dissolving the ozone in the alkali solution film.