Transient plasma-enhanced remediation of nanoscale particulate matter in restaurant smoke emissions via electrostatic precipitation

Abstract

It is now recognized that nanoscale particulate matter (PM) represents a substantial health hazard for our society, including PM from restaurant smoke. In this study, we explored the use of a transient pulsed plasma in conjunction with an applied DC bias to treat oil aerosols that closely resemble restaurant (i.e., charbroiler) smoke emissions. For polyaromatic olefin PAO-4 and soybean oil, we found that a three-order-of-magnitude reduction in particulates (i.e., 99.9% remediation) could be achieved with this system. Here, the plasma discharge was produced in a 4-in.-diameter cylindrical reactor with a 5–10ns high voltage (30 kV) pulse generator together with applied DC bias voltages up to 10kV. The distribution of nanoparticle sizes was measured using a scanning mobility particle sizer (SMPS) with diameter centered around 225nm. Here, the main mechanism of remediation occurs in a two-step process in which the oil nanoparticles are first ionized by the free electrons and free radicals in the plasma and then the charged particles are swept out to the sidewalls of the reactor by the applied DC potential. We believe this general approach opens up new degrees of freedom in the design of electrostatic oil aerosol pollution control devices.