영가철을 이용한 유기오염물질의 산화분해

Abstract

. Iron is one of the most abundant elements on the earth. It exists in a wide range of oxidation states. Zero-valent iron (ZVI) has the best reactivity in various forms of iron. So the studies trying to use ZVI for environmental remediation have implemented for several decades. The treatments using ZVI can be classified into reductive or oxidative reaction. In reductive reaction, target materials directly get electrons from ZVI for degradation or metallic ion uptake. In the other hand, ZVI generates OH radicals by reacting with oxygen in the case of oxidative reaction. In this study, we studied on the oxidative reaction and the effects of magnetic field on that. ZVI can be converted to iron oxide in water. It acts as an inhibitor hindering from transferring electrons from ZVI to oxygen or something. Among various kind of iron oxides, magnetite is well known as dominant species on the surface of ZVI. In the presence of magnetic field, magnetite is more easily dissolved into water. We found that magnetite dissolution rate is two times faster than one in the absence of magnetic field. It means that ZVI is well dissolved into water and it reduces oxygen faster, which is followed by generating OH radicals.

This study aims to understand the oxidative degradation of organic compounds utilizing zero-valent iron (ZVI) which is further promoted under ultraviolet light (UV). The oxidative degradation using ZVI is based on the Fenton reaction, which is the reaction between ferrous ion and hydrogen peroxide generating OH radical. It has to include ferrous salt for ferrous ion. However, the anion originated from ferrous salts is not only unnecessary to accomplish the reaction. It also inhibits the degradation of pollutants as it consumes OH radicals. So ZVI oxidative process emerged as alternative method. ZVI and oxygen in water make hydrogen peroxide and ferrous ion to accomplish the Fenton reaction. Then OH radical and ferric ion is generated. At this point, there is a method using ferric ion for degradation by itself. It is by ultraviolet light. Ferric ion exists as various structures in aquatic system. Among these forms, Ferric monohydroxide can absorb light near 280 nm wavelength to be photo-reduced and make an OH radical. When we combine ZVI oxidative process with photo-reduction of ferric ion, we accomplish two times higher degradation efficiency than normal ZVI process.