Effect of the surfactant treatment using nanosecond pulsed powers

Recently, water pollution is one of environment issues around the world. Consumption of surfactants which is one of organic solvents has increased for industrial and domestic usages, because environmental load of surfactants is lower than that of the other organic solvents. We have studied a water treatment using nanosecond pulsed powers. Discharge plasmas generated by the nanosecond pulsed powers efficiently produce active species which are applicable to water treatments. The water treatment by nanosecond pulsed power utilizes not only the species but also actions of discharges. A water treatment system was developed to increase density of the active species and discharges could strongly affect water. To realize the features, a dielectric barrier in electrodes was adopted for the system to decrease electrode-separation in the reactor in addition to use of nanosecond pulsed powers. The degradation of the surfactant was evaluated by chemical oxygen demand depending on a consumption of potassium permanganate (CODMn) which was widely used for assessments of drainage water in Japan. The initial CODMn was about 80 mg/L. The CODMn of treated solution was decreased mildly for 30 minutes of treatment and then the CODMn increased. The CODMn of the solution treated by pulsed power was approximately 20 mg/L higher than that by only ozone gas generated with an external ozonizer. The difference between the CODMns was caused by the hydrogen peroxide produced by OH radical because of electric discharges in using pulsed power. On the other hand, foaming property, as a behavior of surfactants, reduced faster than the treatment ozone gas generated externally.