Nitration Mechanism of Hot Plasma Pulsed Radiation for Electric Spark Discharge

The mechanism reaction of species formed in an aqueous solution under the action of a remote spark discharge on solutes was studied. The main active factor was radiation. To generate species, hot plasma radiation of electric spark discharge and, for comparison, a corona electric discharge was used. A solution of phenol in water with a concentration of 25 mg/L (2.65
$\times \,\,10^{-4}$
mol/L) was chosen as a probe. A generator of hot plasma radiation had a discharge power of 0.4 J/s, and the volume of processed liquid was 10 mL. A generator of corona electric discharge had power released in the discharge power of 4.7 J/s, and the volume of the processed liquid was 50 mL. Degradation of phenol in aqueous solution was observed under the action of both sources of active species. It was found that under the action of a corona discharge, phenol is destroyed directly during treatment, and practically, no changes take place two days thereafter. Under the action of a hot plasma radiation, changes in phenol concentration during treatment were insignificant, but degradation of phenol took place after processing. The main product formed during degradation is 4-nitrophenol and phenol nitration takes up to 120 h. Oxidation of phenol under plasma radiation does not take place. The results obtained allow us to conclude that one of the possible mechanism reactions under hot plasma radiation is nitration.