펜톤반응에서 pH의 변화에 따른 산화 및 환원반응메카니즘

Abstract

1-핵산올과 사염화탄소를 이용하여 펜톤반응내 산화 및 환원 메커니즘을 조사하고자 pH를 3에서 12까지 변화를 두면서 과산화수소의 농도변화에 따른 유기물질의 분해율을 측정하였다. 1-헥산올의 분해율은 pH가 증가함에 따라 급격하게 감소하는 경향을 보였는데 pH 3에서 1470 mM 과산화수소를 주입한 결과 30 min 동안 99.9%의 제거율을 보였으며 pH 12에서는 5%의 제거율을 보였다. 반면 사염화탄소의 경우 pH가 3에서 5로 증가함에 따라 95%에서 70%로 감소하는 경향을 보였으며 pH가 5에서 12로 증가함에 따라 제거율이 다시 95%로 증가하는 결과를 보였다. 펜톤반응에서 hydroxylradical (OH·)및 환원제의 발생을 알아보기 위해서 pH 3과 9에서 여러가지 스캐빈저를 적용한 실험을 실시하였다. 1-헥산올의 분해는 OH·에 의한 산화반응으로 사염화탄소의 분해반응은 superoxide radical (O2(-)·)과 hydroperoxide anion (OOH(-))에 의한 환원작용으로 설명되어질 수 있다. 이러한 결과는 펜톤반응이 산화 및 환원반응이 공존하는 반응임을 나타내고 있다. The mechanisms of oxidation and reduction in Fenton's reagent were investigated using 1-hexanol and carbon tetrachloride (CT). Degradation of these compounds was investigated using different concentrations of hydrogen peroxide (2.94 mM ~ 1470 mM) at 1 mM concentration of ferric sulfate by varying pH from 3 to 12. The results showed that as pH was increased from 3 to 5, 7, 9, and 12, the degradation of 1-hexanol decreased significantly. Within 30 min (with 1470 mM of H2O2) of reaction time, decomposition of 1-hexanol was 99.9% at pH 3 ; however, only 5% was observed at pH 12. Carbon tetrachloride degradation showed different result; with 1470 mM of H2O2, 95% of initial CT concentration was decomposed at pH 3, but only 70% decomposed at pH 5. When pH was raised to 12, CT degradation reached up to 95% of the initial concentration. Furthermore, competition reactions were conducted at pH 3 and pH 9 to verify the formation of hydroxyl radical and reductants in Fenton's reagent. It was concluded that hydroxyl radical was the primary oxidant for the degradation of 1-hexanol, whereas in the degradation of CT, not the hydroxyl radical, but the reductants, superoxide radical and hydroperoxide anion were involved. This study indicates that Fenton reaction is a co-existing process of oxidative-reductive reaction.