Formation of Nitrite- and Nitrate-Ions in Aqueous Solutions Treated with Pulsed Electric Discharges

Abstract

The accumulation of nitrogen-containing ions formed in aqueous solutions dispersed in air and treated with pulsed corona, dielectric barrier and spark electric discharges, was studied dependent on electric conductivity and pH of treated solutions. The impact of conductivity to the spark and corona discharge is determined by the increased ohmic losses in the reactor. In contrast, the character of dielectric barrier discharge is significantly changed with growing conductivity resulted in increased nitrite-to-nitrate ratio. In alkaline solutions the production of nitrites is increased for the spark and the barrier discharge; the corona discharge produce only nitrates. The amount of nitrates produced in pulsed corona discharge at energy doses characteristic for potable water treatment is about 100 times lower than their maximum permissible concentration.

Pulsed Corona Discharge Induced Hydroxyl Radical Transfer Through the Gas-Liquid Interface

“…In agreement with previous findings 14 , the dissolved TN in treatment under air was found to consist only of NO 3 − . Without oxygen, also NO 2 − was identified, which may simply be explained by the absence of O 3 since dissolved O 3 readily oxidizes NO 2 − , producing mainly NO 3 − and O 2 ( 1 Δ g ) 16 .…”

“…In agreement with previous studies 13 , 14 , the indifference towards pulse frequency indicates that only short-lived species present during and shortly after the pulses contributed to NO x formation (OH radical lifetime on water surface is ~2.7 µs 15 , 1–2 orders of magnitude longer above the surface 5 ). Under N 2 , however, the TN formation rate at 1.98 g kWh −1 was almost half that in air, 3.69 g kWh −1 .…”

“…Under N 2 , however, the TN formation rate at 1.98 g kWh −1 was almost half that in air, 3.69 g kWh −1 . It should be noted that the yield in air is over twice the TN 1.77 g kWh −1 calculated from NO 3 − formation presented in 14 , which is probably due to the water being introduced in aerosol form, rather than the previously applied showering approach, substantially increasing the gas-liquid contact area (see Experimental Methods). The dissolved TN evolution observed under N 2 , i.e.…”

Hospital Wastewater Treatment with Pilot-Scale Pulsed Corona Discharge for Removal of Pharmaceutical Residues

“…For comparison, PCD alone reduced turbidity by 47% and color by 58% via oxidative bleaching. A mild increase in conductivity can be observed during PCD treatment, which is likely a result of nitrate formation during the process from ambient nitrogen [56]. These results are presented in Supplementary Information Table 2 with other characteristic parameters.…”

Potential of electric discharge plasma methods in abatement of volatile organic compounds originating from the food industry

“…This phenomenon, sometimes together with the residual ozone in treated air, presents the basic drawback of non-thermal plasma application to air treatment. Nitric oxides formed in PCD, however, are solely of their highest oxidation state converted easily to aqueous nitrates with moderate yield (Kornev et al, 2013).…”