Electrostatic charge distributions on airborne microorganisms.
Mainelis-G; Willeke-K; Grinshpun-S; Reponen-T; Trakumas-S; Baron-P
American Industrial Hygiene Conference and Exposition, May 20-25, 2000, Orlando, Florida. Fairfax, VA: American Industrial Hygiene Association, 2000 May; :41-42
Several studies showed that bacteria suspended in liquid may carry as many as 10,000 elementary charges. This study was undertaken to determine the electrical charge distributions on bacteria in the airborne state. This information is important. since high electric charges on airborne microorganisms may result in high transport losses in flow systems. High electric charges also suggest that the sampling of airborne microorganisms by an electrostatic collection technique, a potentially "gentle" bioaerosol collection method, may be possible without the need for prior charging. Thus, to investigate the charge on airborne bacteria, we built a new experimental system in which bacteria are aerosolized and then channeled into a parallel plate mobility analyzer. By adjusting the electric field inside the analyzer we selected bacteria carrying known charge ranges. By comparing their concentrations with those entering the analyzer, we obtained the electrical charge distributions on the bacteria. Our tests with Pseudomonas fluorescens bacteria, commonly found in air environments, have shown that airborne bacteria have a net negative charge, but the individual bacteria can be charged either negatively or positively. When the bacterial suspension was aerosolized with compressed air, the bacteria acquired up to approximately 14,000 elementary charges per bacterium; 50% of these bacteria carried between -1000 and +400 elementary charges. When the same bacterial suspension was aerosolized using bursting bubbles, the bacteria acquired maximum charges of approximately 1500 and 50% of the bacteria had between -200 and +150 electrical charges. Thus, aerosolized bacteria have sufficiently high electric charges to be collected by an electrostatic field without prior charging.
Bacteria; Electrical-charge; Airborne-particles; Microorganisms; Fluids; Air-flow; Aerosol-sampling; Air-sampling-techniques; Electrostatic-fields; Sampling-equipment; Sampling-methods; Aerosol-particles; Particle-aerodynamics; Electrical-fields; Analytical-instruments; Laboratory-testing
American Industrial Hygiene Conference and Exposition, May 20-25, 2000, Orlando, Florida
University of Cincinnati