Retraction: Plasma Acid: Water Treated by Dielectric Barrier Discharge

Abstract

It is demonstrated that direct exposure of deionized water to a dielectric barrier discharge (DBD) plasma creates an acid (pH % 2) and is in fact, a strong oxidizer (providing, e.g., peroxidation of a cell membrane). This study addresses the question: which acid is created in water by plasma treatment. Two major possibilities are considered: nitric/nitrous acid and an acid which consist of a hydrogen cation (H þ ) and a superoxide anion (O À 2 ), which, for the lack of a better term, we call plasma acid. The presence of nitric/nitrous acid in the water after plasma treatment in air is confirmed, although the observed pH % 2 cannot be completely explained by the production of nitric acid. Moreover, experiments with oxygen-plasma treatment of water also lead to high acidity, without production of nitrogen based acids at all. Therefore, O À 2 , the conjugate base of the plasma acid, is at least partially responsible for both lowering of the pH and the increase in the oxidizing power of the solution. Experiments indicate that peroxides such as H 2 O 2 and O À 2 , together with an acidic environment are likely to be responsible for the oxidation properties of the plasma treated water. This plasma acid remains stable for at least a day, depending on the gas where plasma is generated, but the effect is temporal. Existence of a temporal and stable oxidizer created using the plasma treatment of pure water not only raises interesting scientific questions and possibilities, but is also likely to provide many applications in situations where direct plasma treatment may be difficult to achieve. Plasma Process. Polym. 2012,

Improvement of water quality using dielectric barrier discharge plasma

“…In other words, DBD plasma created acidity in all types of water. The similar results with DI water were reported in Natalie et al and Oeminhem et al [1,2]. DI water achieved pH≈ 2 after 60 minutes treated and keep it stable in a long time later while wastewater and surface water need 135 minutes to gain pH ≈ 2.…”

“…The other important things are superoxide radicals, which were the result of reaction between ozone and water. This result and mechanism also explained in Natalie et al and others study [1,3]. The acid, which from superoxide O 2 , and H + radical was called plasma acid.…”

“…These types of damage result in metabolic defects, including auxotrophy for aromatic, branched-chain, and sulfur-containing amino acids. Superoxide cannot damage membranes in bacteria but they destroyed bacteria through damage DNA and enzyme of bacteria [1,2,14]. Results of increase acidity in water also support this opinion.…”

“…and Oehmingen et.al. Natalie's research shown that deionized water has pH≈ 2 after 90 minutes treat with DBD plasma [1][2]. So, the control acidity in water during plasma treatment is important in using plasma technology to water treatment.…”

Non-thermal plasma-activated water inactivation of food-borne pathogen on fresh produce

“…were achieved in the current researches where plasma discharge can lead to the acidification of treated water [35,36,49,50]. Although the pH of 10-PAW and 20-PAW is low, the critical pH to initiate S. aureus inactivation is 2 [51].…”