Pulsed corona discharge for degradation of aqueous humic substances

Abstract

The research into oxidation of aqueous humic substances (HS) with pulsed corona discharge (PCD) was undertaken to estimate the energy efficiency of the treatment. The PCD system consists of a voltage pulse generator and reactor, in which the gas-phase discharge generating OH radicals and ozone treats the water showered between electrodes. The influence of HS initial concentration, pulse repetition frequency, water flow rate, and the atmosphere composition was evaluated by the decrease in total organic carbon (TOC) and color. The PCD treatment reduced TOC by 40 to 50% and the color by up to 97%. The PCD energy efficiency ranged about 20 g kW−1 h−1 in air and 30 g kW−1 h−1 in oxygen for the lowest initial color of about 50 Pt-Co degrees. Ozone contributed about 30% to the color reduction and only 15% to the reduction in TOC, indicating predominant role of OH radicals in mineralization of oxidation by-products.

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

“…The gas-phase discharges most efficient in water treatment are dielectric barrier and corona discharges, giving high outcomes of active oxygen-based oxidants (Kornev et al 2006;Panorel et al 2011;Pokryvailo et al 2006;Samoilovich et al 1997). "Thermal" spark and arc discharges, seldom applied for water treatment, are characterized with high, up to 10,000 • C, temperature in the discharge channel and may be used for the initiation of high-temperature reactions and emission of UV-radiation.…”

“…The described PCD treatment method showed the energy efficiency at least 2.2 times exceeding the one of traditional ozonation when applied to humic substances oxidation (Panorel et al 2011). Also, the advantage of PCD treatment is relatively simple design of the equipment: the discharge is insensitive towards the gas humidity; the reactor is a closed compartment in which the treatment takes place making the gas transport and the residual ozone destruction unnecessary.…”

“…Various discharge systems were proposed: spark discharge (SD) in gas bubbles (Anpilov et al 2001), pulsed corona discharge (PCD) over the water surface , flash corona over the water surface (Aristova and Piskarev 2001), and PCD in water aerosol (Pokryvailo et al 2006). The authors earlier proposed pulsed dielectric barrier discharge (PDBD) used in a gas-liquid system (Yavorovsky et al 1997), and PCD (Panorel et al 2011), where water was dispersed in air in the form of droplets, jets and films sized up to a few millimetres forming a sufficient interface at the moderate energy expense. The local strengthening of electric field at the water surface results in predominant formation of surface discharge (Kornev et al 2006).…”

Humic acid and trihalomethane breakdown with potential by-product formations for atmospheric air plasma water treatment

“…Similar results have been reported by Gao et al [39] for the degradation of 17b-estradiol in water by DBD. Panorel et al [32] also reported similar increases in the reaction rates for pulsed corona treatment of aqueous humic acid. The effect of the initial concentration of humic acid solution on the degradation efficiency is presented in Fig.…”

“…It is known that dielectric barrier discharge (DBD) plasma initiates several physical processes (UV light, shock waves) and chemical processes (O , O 3 , H 2 O 2 ) [29], processes which may directly or indirectly act on humic substances. However, limited studies investigate the potential of atmospheric plasma for the breakdown of THMs [30] and HA [31,32]. It is also important to understand the potential for the formation of DBPs after plasma treatment of humic substances to demonstrate the technology's suitability for water treatment.…”