title: Kinetics study on the degradation of a model naphthenic acid by ethylenediamine-N,N'-disuccinic acid-modified Fenton process.
abstract: Naphthenic acids (NAs) are reported to be the main species responsible for the oil sands process-affected water (OSPW) toxicity. In this study, the degradation of cyclohexanoic acid (CHA) as a model compound for NAs by an ethylenediamine-N,N'-disuccinic acid (EDDS)-modified Fenton process was investigated at pH 8. Optimum dose for Fe-EDDS (EDDS:Fe=2:1) was 0.45mM, and 2.94mM for hydrogen peroxide (H2O2). The time profiles of the main species in the process were studied, including CHA, H2O2, Fe(II), total Fe, and Fe-EDDS (in the main form of Fe(III)EDDS). The second-order rate constant between EDDS and hydroxyl radical (OH) at pH 8 was obtained as 2.48±0.43×10(9)M(-1)s(-1). OH was proved to be the main species responsible for the CHA degradation, while superoxide radical (O2(-)) played a minor role. The consecutive addition of H2O2 and Fe-EDDS led to a higher removal of CHA compared to that achieved by adding the reagents at a time. The half-wave potential of Fe(III/II)EDDS was measured at pH 7-9. The EDDS-modified Fenton process is a promising alternative to degrade NAs.
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Klamerth
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
authors.forename: Selamawit Ashagre
authors.initials: SA
authors.lastname: Messele
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada.
authors.forename: Pamela
authors.initials: P
authors.lastname: Chelme-Ayala
authors.affiliation: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, T6G 1H9, Canada. Electronic address: mgamalel-din@ualberta.ca.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Gamal El-Din
keywords: Cyclohexanoic acid; Ethylenediamine-N,N’-disuccinic acid; Fenton process; OH; Redox potential