Decomposition of Persistent Organic Compounds in Water Using Pulsed Discharge on Water

Abstract

Acetic acid simulating a persistent organic compound in water was decomposed by a discharge on water using a thin blade electrode. The thin blade electrode facilitates the generation of wide-ranging discharges on water. The effect of differences in the species of the supply gas and the discharge power on the decomposition of acetic acid was investigated. Compared with argon, when helium was used, a larger amount of acetic acid was decomposed. Experiments also confirmed that the decomposition rate of acetic acid rose with the discharge power. It was also found that the decomposition efficiency was improved when the discharge power was reduced.

Characteristics of Underwater Plasma with Surfactant

“…Particularly, OH radicals having oxidation potential next to that of fluorine are supposed to be able to decompose persistent organic substances resistant to ozone. 4,5 We and other researchers proposed an underwater plasma source using porous membranes as a dielectric and bubble generating element. 6,7 In this method, dielectric barrier discharges are formed in water so that cooling of liquid phase and reaction vessel is unneeded in principle.…”

Characteristics of an Underwater Plasma Source with a Porous Glass Membrane

“…Consequently, much attention is now being attracted by the efficient use of OH radicals and O radicals, which have higher oxidation potentials than ozone (2.81 V and 2.42 V, respectively, against 2.07 V). In particular, OH radicals have a high oxidation potential, next to that of fluorine (2.89 V), thus offering the possibility of decomposition of humins, acetic acid, and other recalcitrant organic substances resistant to ozone [3,4]. There are a number of methods of generating OH radicals, such as the O 3 /H 2 O 2 method, known as an advanced oxidation process (AOP), the H 2 O 2 /UV method, and the O 3 /UV method [2].…”

“…There are various methods of generating OH radicals by direct decomposition of water, such as the arrangement of electrodes near the water surface, generation of active species in bubbles under water by applying a strong electric field [6,7], and the use of cavitation [8] or a plasma jet [9,10]. In addition, there are numerous reports of the use of gas-liquid interface plasmas for the decomposition of recalcitrant organic substances [3,4] or of inactivation tests for fungi and other microorganisms [9][10][11]. The underwater discharge plasma generators proposed by us and other researchers [12,13] supply microbubbles to the gas phase through a porous glass membrane, while generating a discharge at the gas-liquid interface of the bubbles formed inside the pores or on the membrane surface.…”