Combined of dielectric barrier discharge and electrolysis methods to generate nitrogen compounds in aqueous solution from room air
Yoshihiro Kawada*, Hiroto Endo, Hiroki Yamanaka, Hirotaka Shimizu
* The author to whom correspondence should be addressed.
Electrical Environmental Energy Engineering Unit, Polytechnic University of Japan, Japan
Abstract
Hydroponics is the process of growing plants without soil medium in an aqueous solution containing the required nutrients. For this technique, phosphorus, potassium, and nitrogen fertilizers are added to the water. Nitrogen gas in the atmosphere cannot be absorbed directly by plants, and the nitrogen must be transformed into nitrate, nitrite, and ammonia for uptake by plants. Previous research has shown that dielectric barrier discharge products from air affect plant growth. Only nitrogen oxides are produced from electric discharge in air, and the aqueous solution of nitrogen oxide is nitric acid, which has low pH. Therefore, pH adjustment is necessary for hydroponics. In this study, electric discharge products were dissolved in water, and then, the solution was kept for 24 h as ozone was degassed. Subsequently, nitrate was reduced by electrolysis. In this study, the pH of the solution containing the electric discharge products was increased to 5.5 or more. Our past research had shown that the pH can be increased by using a metal electrode and electrolysis; however, metal ions are dissolved by electrolysis. In this study, a graphite electrode was used; additionally, the electrolyte was separated using a dialysis membrane, and the area of the cathode electrode was increased. The stirring bar was set under the cathode electrode. These methods were tested to evaluate the effect on electrolysis and rising the pH.
Keywords - Ozone, electrolysis, nitrate, nitrite, ammonia.
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