Lindsey Faye Whitmore

Novel applications of natural charge exchange phenomena in domestic aerosol products

The droplets produced by commercially available pressure-pack dispensers, of the type used to control insects or to fragrance rooms, invariably carry a unipolar charge. This is usually quite low (charge-to-mass ratio of about 10/sup -8/ to 10/sup -5/ C.kg/sup -1/) and is not considered to be of practical use in any potential application. We report a new technology which increases the charge-to-mass ratio generated on these droplets to a level in excess of 1/spl times/10/sup -4/ C.kg/sup -1/, without the need for an external power supply. This has been achieved by redesigning the actuator component of these dispensers in order to enhance the charge separation processes that occur naturally during atomisation. These design modifications assume that charged droplets are generated as a result of shearing of the electrical double layer at the liquid-solid interface. As a result of this increased electrostatic charge the performance of insecticide and room fragrance sprays was modified and enhanced. The rate of knockdown of houseflies by an insecticide spray was 34% faster if the charge-to-mass ratio of the liquid aerosol was increased from 2.5/spl times/10/sup -5/ C.kg/sup -1/ (negative polarity) to 1.1/spl times/10/sup -4/ C.kg/sup -1/ (negative). Liquid aerosols of the type used to fragrance rooms were found also to remove dust particles from the air. Depletion of airborne particles was increased by 18% if the charge-to-mass ratio of these droplets was enhanced from 1.3/spl times/ 10/sup -6/ C.kg/sup -1/ (negative) to 1.4/spl times/10/sup -4/ C.kg/sup -1/ (negative).