Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II)
Environmental Science & Technology
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Abstract
Production of elemental mercury, Hg(0), via Hg(II) reduction is an important pathway that should be considered when studying Hg fate in environment. We conducted a kinetic study of abiotic homogeneous and surface-catalyzed Hg(0) production by Fe(II) under dark anoxic conditions. Hg(0) production rate, from initial 50 pM Hg(II) concentration, increased with increasing pH (5.5–8.1) and aqueous Fe(II) concentration (0.1–1 mM). The homogeneous rate was best described by the expression, rhom = khom [FeOH+] [Hg(OH)2]; khom = 7.19 × 10+3 L (mol min)−1. Compared to the homogeneous case, goethite (α-FeOOH) and hematite (α-Fe2O3) increased and γ-alumina (γ-Al2O3) decreased the Hg(0) production rate. Heterogeneous Hg(0) production rates were well described by a model incorporating equilibrium Fe(II) adsorption, rate-limited Hg(II) reduction by dissolved and adsorbed Fe(II), and rate-limited Hg(II) adsorption. Equilibrium Fe(II) adsorption was described using a surface complexation model calibrated with previously published experimental data. The Hg(0) production rate was well described by the expression rhet = khet [>SOFe(II)] [Hg(OH)2], where >SOFe(II) is the total adsorbed Fe(II) concentration; khet values were 5.36 × 10+3, 4.69 × 10+3, and 1.08 × 10+2 L (mol min)−1 for hematite, goethite, and γ-alumina, respectively. Hg(0) production coupled to reduction by Fe(II) may be an important process to consider in ecosystem Hg studies.
Suggested Citation
Amirbahman, A., Kent, D.B., Curtis, G.P., Marvin-DiPasquale, M.C., 2013, Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II): Environmental Science & Technology, v. 47, no. 13, p. 7204-7213, https://doi.org/10.1021/es401459p.
ISSN: 1520-5851 (online)
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Kinetics of homogeneous and surface-catalyzed mercury(II) reduction by iron(II) |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/es401459p |
| Volume | 47 |
| Issue | 13 |
| Publication Date | June 17, 2013 |
| Year Published | 2013 |
| Language | English |
| Publisher | ACS Publications |
| Contributing office(s) | National Research Program - Western Branch |
| Description | 10 p. |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Environmental Science and Technology |
| First page | 7204 |
| Last page | 7213 |