The Transformation of Fine Dust Is 'Innocent'... Using Nitrogen Oxides as Catalysts for Wastewater Purification

KIST Research Team Develops Nitrogen Oxide-Based Catalyst to Decompose Recalcitrant Organic Compounds in Wastewater

[Asia Economy Reporter Kim Bong-su] A technology that purifies contaminated water such as sewage and wastewater using nitrogen oxides, a major cause of fine dust, has been developed by domestic researchers.

The Korea Institute of Science and Technology (KIST) announced on the 19th that a research team led by Dr. Kim Jong-sik and Dr. Ha Heon-pil from the Extreme Materials Research Center, in collaboration with Professor Cho Geun-hong’s team from the Department of Physical Chemistry at the Korea Military Academy, recently developed a high-efficiency nitrogen oxide (NOX)-based decomposer (radical) catalyst for water treatment capable of decomposing refractory organic compounds in sewage and wastewater.

Nitrogen oxides are mainly included in exhaust gases from automobiles and power plants. They react with light to convert into ultrafine dust and, along with sulfur oxides, are known as serious causes of fine dust.

The research team found a way to utilize nitrogen oxides not just for removal but as a material to purify sewage and wastewater. Currently, refractory organic compounds such as phenol and bisphenol A, which are difficult to decompose in contaminated water, are mainly removed by adding coagulants to precipitate them to the bottom or by injecting excessive amounts of hydrogen peroxide (H2O2) or ozone (O3), substances that convert into organic decomposers (OH radicals), to transform the organics into water, carbon monoxide, carbon dioxide, etc. However, coagulants require a separate process to remove the coagulated precipitates again. Decomposers lose their decomposition ability after breaking down organics and volatilize, making them usable only once.

Accordingly, NO3 decomposers, which have a longer lifespan and superior organic decomposition ability compared to existing decomposers, are emerging. However, NO3 decomposers can only be produced by injecting very high energy under the presence of radioactive materials or by satisfying stringent conditions such as extreme acidity.

The research team developed a catalyst synthesis method that easily converts nitrogen oxides (NOx), previously considered only as targets for removal, into NO3 decomposers. The technology developed by the team features fixing nitrogen oxides (NO3) on the surface of a manganese dioxide catalyst. Nitrate was easily fixed on the catalyst surface in air at a low temperature below 150°C, and when this catalyst and hydrogen peroxide were added to water, NO3 decomposers fixed on the catalyst surface could be generated. Hydrogen peroxide injected into the water is converted into OH decomposers by the manganese dioxide metal oxide catalyst, and the generated OH decomposers convert the NO3 present on the catalyst surface into decomposers.

The NO3 decomposers generated in this way showed 5 to 7 times higher sewage and wastewater purification efficiency than existing decomposers. The research team confirmed this through experiments with actual dyeing wastewater. The metal oxide catalyst containing the immobilized NO3 decomposers has low process costs, making its manufacturing cost more than 30% cheaper than existing catalysts (iron salts) and easy to mass-produce. Unlike existing catalysts that could only be used once, it can be reused at least 10 times.

Dr. Kim Jong-sik of KIST stated, “The technology has currently been transferred to a domestic environmental company,” adding, “The catalyst is easy to mass-produce and can be directly applied to existing sewage and wastewater treatment processes, and it is expected to be commercialized in the water treatment industry soon.”

The research results were published in the latest issue of the American Chemical Society journal ‘JACS Au.’

This content was produced with the assistance of AI translation services.