KOSEN 한인과학기술자네트워크

Energy/resource recovery from environmental pollutants using nanotechnology

The discharge of poorly-treated pollutants into natural environments has been considered as a great environmental problem due to the rapid increase of toxic chemicals from extensive agricultural and industrial activities. Recently, researchers try to produce energy/resource from various organic and inorganic pollutants by a variety of processes, including combustion, gasification, anaerobic digestion, and landfill gas recovery. Herein, We propose the catalytic conversion of organic pollutants (e.g., carbon tetrachloride and 4-nitropheonol) to useful energy/resource those can produce useful energy (methane and H2) and resource (4-aminophenol), respectively. The novel materials (cheap, stable, recyclable, eco-friendly, and readily available) synthesized from the iron catalysts research (see above) can be applied to this research with the addition of other chemical initiators such as NaBH4. Pollutant to energy/resource is one of the cornerstones of any efficient pollutant management system and a way to secure energy supplies for the future.

Development of Green-SMART remedial nano technology (soil and groundwater)

We have developed novel remedial technologies to eco-friendly and economically treat soil and groundwater contaminated by organic and inorganic pollutants. Although we have developed several geo-biological remedial technologies for typical contaminants (chlorinated organics, nitrate, and, heavy metals), there is still a considerable amount of research work to perform in this area. An important extension of this research work will be to develop effective and selective in-situ and ex-situ remedial technologies that can transform the contaminants into non-toxic products. Most of the works have focused on the “effectiveness” on the removal of the contaminant when they develop new remedial technology. However, the limited application such as toxicity of nano-materials and production of toxic byproducts has continuously arisen in these technologies. Therefore, the goal of this research is to develop Green-SMART remedial technology by Green materials (surface modified natural and biogenic mineral) and SMART system (selective degradation of contaminant to non-toxic products).

Development of redox catalysts for water and air treatment

Discharge and emission of persistent pollutants from industrial and domestic activities to surface water and air systems have continuously reported to date. Conventional treatment technologies (biological, chemical, and physical) have revealed some limitations for removal of emerging pollutants. Recently, catalytic redox removal of persistent pollutants has attracted attention in environmental science and engineering due to its powerful redox potential and easy operation. Especially, advanced oxidation processes (AOPs) and H2 mediated catalytic reaction could be promising alternatives to effectively treat the air and wastewater contaminated by persistent pollutants. Accordingly, We have developed nanoscale Fe based catalysts for oxidative degradation of organic contaminants (pharmaceuticals and chlorinated organics) and for reductive degradation of nitrate and nitrite. However, degradation efficiency and selectivity toward less-toxic products should be much improved for application in the field study. To solve these problems, we will develop novel redox catalysts using reactive metals supported by iron soil minerals, leading to easier controlling the redox behavior of contaminants. This research approach can result in significant enhancement of selective contaminant removal.

Controlling fate and transport of radionuclides by geo-biochemical reactions

After the Fukushima nuclear power plant accident, not only the safety of the nuclear power plant but also the safe disposal of high-level radioactive waste has been attracted attention worldwide. The potential release of radionuclides from interim storage sites as well as the transport/retention of radionuclides in the multi-barrier system of a deep geological repository is a focus and challenge of current fundamental and applied research. In an environment of the deep underground disposal site, groundwater is known as a media for transport of radionuclides when the radionuclides are leached from radioactive waste disposal container. Thus, the investigation of radionuclide transport considering the solubility, adsorption, and complexation reactions should be conducted in complex water- rock (mineral) interfacial reactions. Typically, migration of redox-sensitive actinides (e.g. U, Np) and long-lived fission products (e.g. Tc, Se) is strongly influenced by the in-situ redox conditions. We have used Fe materials for redox stabilization of the radionuclides because they are abundant as aqueous and solid phases in deep underground disposal sites. In addition, specific microbes (e.g., Geobacter and Shewanella) we used can reduce Fe(III) to Fe(II) in anoxic condition that can promote the immobilize the specific radionuclide such as U. Therefore, we plan to investigate the effect of various geo-biochemical interactions and their sequence/order on the fate and transport of radionuclides.