You are here:
Fenton-like Degradation of MTBE: Effects of Iron Counter Anion and Radical Scavengers
Hwang, S., S. G. HULING, AND S. Ko. Fenton-like Degradation of MTBE: Effects of Iron Counter Anion and Radical Scavengers . CHEMOSPHERE. Elsevier Science Ltd, New York, NY, 78(5):563-568, (2010).
observing the effects of iron counter anion and radical scavengers
Fenton-driven oxidation of Methyl tert-butyl ether (MTBE) (0.11-0.16 mM) in batch reactors containing ferric iron (5 mM), hydrogen peroxide (H2O2) (6 mM) (pH=3) was performed to investigate MTBE transformation mechanisms. Independent variables included the form of iron (Fe) (Fe2(SO4)3.9H2O, Fe(NO3)3.9H2O), H2O2 (6, 60 mM), Chloroform (CF) (0.2 – 2.4 mM), Isopropyl alcohol (IPA) (25, 50 mM), and sulfate (7.5 mM). MTBE, tert-butyl alcohol (TBA) and acetone transformation were significantly greater when oxidation was carried out with Fe(NO3)3.9H2O than with Fe2(SO4)3.9H2O. Sulfate interfered in the formation of the ferro-peroxy intermediate species, inhibited H2O2 reaction, hydroxyl radical (•OH) formation, and MTBE transformation. Transformation was faster and more complete at a higher [H2O2] (60 mM), but resulted in lower oxidation efficiency which was attributed to •OH scavenging by H2O2. CF scavenging of the superoxide radical (•O2-) in the ferric nitrate system resulted in lower rates of •O2- reduction of Fe(III) to Fe(II), •OH production, and consequently lower rates of MTBE transformation. IPA, an excellent scavenger of •OH completely inhibited MTBE transformation in the ferric nitrate system indicating oxidation was predominantly by •OH. •OH scavenging by HSO4-, formation of the sulfate radical (•SO4-), and oxidation of MTBE by •SO4- was estimated to be negligible. The form of Fe (i.e., counter anion) selected for use in Fenton treatment systems impacts oxidative mechanisms, treatment efficiency, and post-oxidation treatment of residuals which may require additional handling and cost.