Nitrogen oxides, also known as nitrous gases or NOx gases, are produced by various processes such as the reaction and concentration of nitric acid or the combustion of fossil energy sources. While NOx gases are harmful to health, they are also valuable as a source for nitric acid production.

For example, gases with low NOx content, often produced during combustion processes, are typically converted to nitrogen and water through catalyzed processes with ammonia.

In the case of higher concentrations of NOx, gases are usually directed to wet absorption columns, where the objective is to remove or clean NOx from waste gases and/or produce nitric acid. Scrubbers are designed and manufactured by MDSJ AIR in various sizes and versions to meet your specific needs. If oxygen is not present and the scrubber operates with a non-oxidizing aqueous medium such as water, NOx passes through the scrubber and is dissolved as nitrogen and nitric acid or nitrites and nitrates under caustic conditions. When oxygen is introduced, NO will be oxidized to NO2 in the gas phase. It then converts to nitric acid, which is soluble in water and is a common way of producing nitric acid.

The addition of oxidizing agents to the liquid phase, such as hydrogen peroxide or potassium permanganate, oxidizes nitrites to nitrates and improves the washing process. As the dissolution of metals in nitric acid generates the NOx waste stream, such semi-batch absorption systems are typically provided by us for periodically operated processes.