Chemical destruction of MTBE using Fenton's Reagent: effect of ferrous iron/hydrogen peroxide ratio

Abstract

In previous laboratory experiments Fenton's Reagent (FR) was successfully used as the source of hydroxyl radicals (OH*) for chemical treatment of low concentrations of methyl tert-butyl ether (MTBE) in water. Although under certain conditions MTBE degradation levels as high as 99.99% were achieved, none of these experiments resulted in complete MTBE mineralization. In all cases, these experiments applied FR as an equimolar concentration of ferrous iron (Fe2+) and hydrogen peroxide (H2O2). The present study investigates the effect of H2O2/Fe2+ molar ratio on the extent of degradation of MTBE and intermediate products in water at pH = 3.0. The initial concentration of MTBE studied was 0.0227 mM (approximately 2 mg/L). Initially, the dose of Fe2+ was kept constant at a Fe2+/MTBE molar ratio of 10:1 and the dose of H2O2 was varied to achieve different H2O2/Fe2+ molar ratios. The results revealed that higher degradation efficiency was achieved when FR was used as an equimolar mixture (H2O2/Fe2+ molar ratio = 1.0). The extent of MTBE degradation decreased when the H2O2/Fe2+ molar ratio was changed to values higher or lower than 1.0. These results suggest that a stoichiometric relationship (1:1) between the FR components optimizes the degradation process for this reactant system. It is hypothesized that an excess of H2O2 enhances the effect of reactions that scavenge OH*, while a decreased amount of H2O2 would be a limiting factor for the Fenton Reaction.

Destruction of microcystin-RR by Fenton oxidation

“…Secondly, at the initial stage of the reaction, low-molecule weight organic acids produced by decomposition of MC-RR and other organic compounds could lead to the rapid pH fluctuation. Some similar results have been proved in research on the Fenton oxidation of MTBE [39,45,46].…”

Degradation of methyl tertiary-butyl ether (MTBE) by anodic Fenton treatment

“…The involvement of the iron ions makes it more complicated than the free radical degradation pathways that have been reported [7][8][9][10][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Our discussion of the mechanisms focuses on the uncharted redox reactions that involve iron ions and related free radicals as well as the radical ␣ and ␤ scissions.…”

“…Phytoremediation of MTBE was also studied [22]. In addition, MTBE degradation was carried out in classical Fenton treatment, and the reaction kinetics and degradation products were reported for different operating conditions [12,23,24,26,27]. As a variation of the Fenton reaction, Bergendahl and Thies [28] investigated the feasibility of using zero-valent iron as the source of ferrous iron in the Fenton reaction of MTBE.…”

“…Among the AOPs, the Fenton reaction generates • OH by reducing hydrogen peroxide with ferrous ion (reactions (1)-(3)) [30]. There are many reports on the remediation of pollutants by classic Fenton treatment (CFT) where ferrous salt and hydrogen peroxide are used as reagents [12,[23][24][25][26][27]:…”

Development and optimization of dark Fenton oxidation for the treatment of textile wastewaters with high organic load

“…The oxidation potential of the hydrogen peroxide has been reported to be 1.9 V [17] while the oxidation potential for the hydroxyl radicals is approximately 2.8 V. Using H 2 O 2 , the production of hydroxyl radicals is enhanced by the presence and action of ferrous ion (Fe 2+ ), as a catalyst. In this case, hydrogen peroxide is decomposed to hydroxyl radical and hydroxyl ion, while ferrous ion is transformed into ferric ion.…”