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Abstract
Despite its widespread importance for biological and environmental chemistry and decades of study, the mechanism underlying the Fenton reaction is still a matter of some controversy. To elucidate the pH dependence of this complex reaction, a new kinetic model is developed to explain the increase in rate and mechanistic shift that occurs from acidic to neutral conditions. This mechanism originated from a re-analysis of a previously proposed model, which neglected explicit iron speciation, leading to unrealistic rate constants. Accounting for speciation suggests a much faster formation rate of Fe(IV), which is estimated to be on the order of 106 M-1s-1. Expanding on prior kinetic studies that include speciation under acidic conditions, we propose a unified kinetic model that captures the pH-dependent rate acceleration in Fe(II) oxidation by H2O2, which is a significant step toward resolving the long-standing mechanistic ambiguity of Fenton chemistry.
Supplementary materials
Title
Supplementary Information
Description
S1: Reconstructed Kinetic Model Predictions and Comparison to Experiments
S2: Derivation of k_obs - Eq. 10 in Bataineh et al.
S3: Reconstructed Kinetic Model with Iron Speciation and Faster Fe(IV) Formation Rate
S4: Extracting k_Fe from the Experimental Traces of Bataineh et al.
S5: Unified Kinetic Model - Assumptions and Implementation
S6: Unified Kinetic Model - Faster Equilibrium of the Second Acid Dissociation of Fe(III)
S7: Unified Kinetic Model – Model Predictions and Exponential Fit Uncertainty
S8: Probing Kinetic Feasibility of Fe(OH)^(2+) as a forming reagent to Fe(IV)
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