We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The Kinetics of Aqueous Mercury(II) Reduction by Sulfite Over an Array of Environmental Conditions.
- Authors
Feinberg, Aryeh; Kurien, Uday; Ariya, Parisa
- Abstract
The reaction of Hg with sulfite is a major identified reduction pathway in the atmosphere. UV absorption spectroscopy was used to study the kinetics of Hg reduction by sulfite (NaSO) in the presence of fly ash. Upon the addition of Cumberland and Shawnee fly ash samples, the reduction rates were 0.0071 ± 0.0008 and 0.0009 ± 0.0006 s, respectively. This represents c.a. 40 and 90 % decreases in the homogeneous rate, 0.013 ± 0.007 s. The reduction reaction was also observed when Cumberland was added without NaSO. Sulfur elemental analyzer and high-resolution field emission scanning microscopy with energy dispersive X-ray spectroscopy (HR-FE-SEM-EDS) characterization confirmed that Cumberland fly ash particles were rich in sulfur. Nanoparticle Tracking Analysis (NTA) determined the mean particle size in solution to be 246 ± 25 nm for Cumberland fly ash and 198 ± 14 nm for Shawnee. To obtain further insight on observed Hg homogeneous reduction rates by sulfite, the effects of several environmental variables were investigated. Hg(NO) and HgO were used as the sources of Hg. Extended pH (1-7) and temperature (1.0-45.0 °C) ranges were studied for the first time. The enthalpies of activation for the HgO reduction were 94 ± 3 kJ mol at pH 1 and 92 ± 4 kJ mol at pH 3, while the entropies were 33 ± 9 J mol K at pH 1 and 30 ± 10 J mol K at pH 3. It was determined that increasing ionic strength, especially with nitrate species, slows down the reaction at pH = 7. Significance of the results on the variability of mercury reduction by sulfite at various environmental conditions, and its implication in modelling are discussed.
- Subjects
MERCURY; SULFITES; HETEROGENEOUS catalysis; SURFACE reactions; SURFACE chemistry
- Publication
Water, Air & Soil Pollution, 2015, Vol 226, Issue 4, p1
- ISSN
0049-6979
- Publication type
Article
- DOI
10.1007/s11270-015-2371-0