Radical formation due to discharge inside bubble in liquid

Sterilization, decolorization or deodorization of water using active oxygen species have been of interest because of their strong oxidation performance and they decompose into oxygen molecules which do not pollute the environment. In this paper, studies have been made on generation and characteristics of an electrical discharge in a bubble formed by electrolysis. Radical formation and application of the discharge in water treatment are also reported using a positive stainless-steel needle and a negative aluminum plate. The needle electrode was surrounded with an insulating glass tube. The electrode system was put in a low pressure vessel and energized with dc high voltage. Electrolysis took place and fine oxygen bubbles were formed from the positive needle electrode. Several minutes later the electrical discharge began in an oxygen bubble. An intense light emission due to the generation of OH radical could be observed. The spectroscopic study indicated that hydrogen peroxide was formed without ozone generation by the discharge. The discharge in bubble can be applied in sterilization.