Oxidative Processes Occurring When Pulsed High Voltage Discharges Degrade Phenol in Aqueous Solution

TLDR

The study investigates pulsed high‑voltage discharges for removing phenol from aqueous solution. The authors examined phenol degradation using streamer corona and spark discharges, assessing hydrogen peroxide addition, UV photochemical oxidation, and the formation of intermediate products inside and outside the plasma channel. Spark discharge achieved higher removal efficiency and energy efficiency (6.91 × 10⁻³ μmol J⁻¹) than streamer corona, especially with hydrogen peroxide, and produced hydroquinone, pyrocatechol, and p‑benzoquinone that vanished with extended treatment.

Abstract

In this investigation, results obtained using a pulsed discharge for organic compound removal are presented. The degradation of phenol by a streamer corona discharge and spark discharge, the effects of hydrogen peroxide additive on removal efficiency, and photochemical oxidation by ultraviolet light from the discharge plasma channel were investigated. The intermediate products and final byproducts formed by the spark discharge were also studied. A preliminary study of the degradation mechanism inside and outside the plasma channel was carried out. It was found that the removal efficiency of organic contaminants in the aqueous solution was higher for the spark discharge than for the streamer corona discharge and was greatly influenced by the discharge type and additive. The energy efficiency was the highest (6.91 × 10-3 μmol/J) for the case with hydrogen peroxide injection and spark discharge. The main intermediate products produced by the spark discharge during the treatment process were hydroquinone, pyrocatechol, and p-benzoquinone. These intermediate products disappeared when the treatment time was increased.