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Title: Dissolved organic matter reduces the effectiveness of sorbents for mercury removal

Abstract

Mercury (Hg) contamination of soils and sediments impacts numerous environments worldwide and constitutes a challenging remediation problem. In this study, we evaluate the impact of dissolved organic matter (DOM) on the effectiveness of eight sorbent materials considered for Hg remediation in soils and sediments. The materials include both engineered and unmodified materials based on carbon, clays, mesoporous silica and a copper alloy. Initially, we investigated the kinetics of Hg(II) complexation with DOM for a series of Hg:DOM ratios. Steady-state Hg-DOM complexation occurred within 48 to 120 h, taking longer time at higher Hg:DOC (dissolved organic carbon) molar ratios. In subsequent equilibrium experiments, Hg(II) was equilibrated with DOM at a defined Hg:DOC molar ratio (2.4 · 10 –6) for 170 h and used in batch experiments to determine the effect of DOM on Hg partition coefficients and sorption isotherms by comparing Hg(II) and Hg-DOM. Hg sorption capacities of all sorbents were severely limited in the presence of DOM as a competing ligand. Thiol-SAMMS®, SediMite™ and pine biochar were most effective in reducing Hg concentrations. While pine biochar and lignin-derived carbon processed at high temperatures released negligible amounts of anions into solution, leaching of sulfate and chloride was observed for most engineeredmore » sorbent materials. Sulfate may stimulate microbial communities harboring sulfate reducing bacteria, which are considered one of the primary drivers of microbial mercury methylation in the environment. Here, the results highlight potential challenges arising from the application of sorbents for Hg remediation in the field.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [1]; ORCiD logo [1];  [3]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); National High Magnetic Field Lab, Tallahassee, FL (United States)
  3. Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1542235
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Science of the Total Environment
Additional Journal Information:
Journal Volume: 690; Journal Issue: C; Journal ID: ISSN 0048-9697
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Mercury; Contamination; Remediation; Sorbents; Organic matter

Citation Formats

Johs, Alexander, Eller, Virginia A., Mehlhorn, Tonia L., Brooks, Scott C., Harper, David P., Mayes, Melanie A., Pierce, Eric M., and Peterson, Mark J. Dissolved organic matter reduces the effectiveness of sorbents for mercury removal. United States: N. p., 2019. Web. doi:10.1016/j.scitotenv.2019.07.001.
Johs, Alexander, Eller, Virginia A., Mehlhorn, Tonia L., Brooks, Scott C., Harper, David P., Mayes, Melanie A., Pierce, Eric M., & Peterson, Mark J. Dissolved organic matter reduces the effectiveness of sorbents for mercury removal. United States. doi:10.1016/j.scitotenv.2019.07.001.
Johs, Alexander, Eller, Virginia A., Mehlhorn, Tonia L., Brooks, Scott C., Harper, David P., Mayes, Melanie A., Pierce, Eric M., and Peterson, Mark J. Wed . "Dissolved organic matter reduces the effectiveness of sorbents for mercury removal". United States. doi:10.1016/j.scitotenv.2019.07.001.
@article{osti_1542235,
title = {Dissolved organic matter reduces the effectiveness of sorbents for mercury removal},
author = {Johs, Alexander and Eller, Virginia A. and Mehlhorn, Tonia L. and Brooks, Scott C. and Harper, David P. and Mayes, Melanie A. and Pierce, Eric M. and Peterson, Mark J.},
abstractNote = {Mercury (Hg) contamination of soils and sediments impacts numerous environments worldwide and constitutes a challenging remediation problem. In this study, we evaluate the impact of dissolved organic matter (DOM) on the effectiveness of eight sorbent materials considered for Hg remediation in soils and sediments. The materials include both engineered and unmodified materials based on carbon, clays, mesoporous silica and a copper alloy. Initially, we investigated the kinetics of Hg(II) complexation with DOM for a series of Hg:DOM ratios. Steady-state Hg-DOM complexation occurred within 48 to 120 h, taking longer time at higher Hg:DOC (dissolved organic carbon) molar ratios. In subsequent equilibrium experiments, Hg(II) was equilibrated with DOM at a defined Hg:DOC molar ratio (2.4 · 10–6) for 170 h and used in batch experiments to determine the effect of DOM on Hg partition coefficients and sorption isotherms by comparing Hg(II) and Hg-DOM. Hg sorption capacities of all sorbents were severely limited in the presence of DOM as a competing ligand. Thiol-SAMMS®, SediMite™ and pine biochar were most effective in reducing Hg concentrations. While pine biochar and lignin-derived carbon processed at high temperatures released negligible amounts of anions into solution, leaching of sulfate and chloride was observed for most engineered sorbent materials. Sulfate may stimulate microbial communities harboring sulfate reducing bacteria, which are considered one of the primary drivers of microbial mercury methylation in the environment. Here, the results highlight potential challenges arising from the application of sorbents for Hg remediation in the field.},
doi = {10.1016/j.scitotenv.2019.07.001},
journal = {Science of the Total Environment},
number = C,
volume = 690,
place = {United States},
year = {2019},
month = {7}
}

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This content will become publicly available on July 3, 2020
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