Interactions of organic pollutants with soil components ...of+organic+poll.... · Interactions of...
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Interactions of organic pollutants with soil components – elucidating mechanisms on a molecular level Adélia J.A. Aquino, 1,2 Daniel Tunega, 1,2 Hasan Pašalić, 1 Georg Haberhauer, 3 Ursula Haas, 3 Martin H. Gerzabek, 2 Ar- tur Meleshyn, 4 and Hans Lischka 1,5 Recent Achievements Introduction Environmental pollution is an important subject as it is one of the major problems of modern society. The chemical pollutants produced imply severe threats for the quality of air, water supplies and soils. Soil organic matter (SOM) is the major pool of active carbon on the Earth and humic materials constitute the leading fraction of SOM. Humic substances (HS) occur widely, exerting a potential influence in soil fer- tility, mineral weathering, and water acidity. They are involved in the transport, sequestration, and mitiga- tion of contaminants being usually thought to be pro- duced from the decomposition of plant and animal residues, having a complex macromolecular struc- ture, a high chemical stability and, on top of it, a strong resistance to microbial degradation. HS play a fundamental role in many biogeochemical processes and in the determination of the properties and behav- ior of many different materials in natural systems. They constitute the most profuse reservoir of carbon on earth and might even have an impact on atmos- pheric chemistry throughout the carbon cycle, in which carbon is continuously recycled amongst plants, animals, soil, air, and water. Owing to the ex- treme complexity of HSs, the modeling of them is very challenging and complicated task. Soil minerals represent another important active com- ponent of soils acting in the formation of stable or- gano-mineral aggregates or in the interactions with various pollutants. These processes are fairly com- plex and their better understanding requires a deep insight on them, even at molecular level using tools of molecular modeling. Goals • Improve and develop simulation approaches • Build up realistic theoretical models to reproduce interactions • Determine structural, thermodynamic, and spectroscopic quantities • Evaluate and link theoretical upshots of the modeling to experimental results Hypothe- The behavior of organic compounds on the microscale is distinctly influenced by interactions of theses compounds on the nanoscale Theoretical chemical methods can con- tribute in elucidating the basic processes involved A. Theoretical Molecular Modeling Tools: 1. Quantum Mechanics (QM) – DFTB, DFT and MP2 levels Packages: TURBOMOLE, GAUSSIAN, DFTB+, VASP program packages 2. Molecular Mechanics (MM)- Force-Field parameters for classical potentials Packages: TINKER, DL_POLY, LAMPPS, AMBER Structural Models: 1. Oligomeric and polymeric models of humic substances (e.g. polyacrylic acid chains) 2. Cluster and periodic models of soil minerals (montmorillonites, FeO(OH)) 3. Interacting compounds: acetic acid, MCPA, 2,4-dichlorophenol, PAHs, Bentazone B. Experimental (Isotherms) Substances: MCPA, Bentazone Sorbents: Gumpensteiner soil NPK (2.0% OC; pH 5.4) Ca-Montmorillonite (pH 3.2), ferrihydrite, charcoal 3 different artificial soils Background Solutions: 0.01M CaCl 2 , 0.01M CaCl 2 pH 3 (HCl), 0.1M CaCl 2 Methodological Approaches Exceptional stability of calcium bridges 2.400 2.423 2.362 2.389 2.379 2.420 2.388 2.417 2.393 2.443 2.385 2.371 1.773 1.801 1.859 1.806 2.487 2.34 0 1.63 1.699 1.635 1.875 Acknowledgements Discussion and Contribution to SPPs Grand Goals • Realistic simulations based on reliable quantum chemical methods have been per- formed for several interesting problems in soil science • It has been demonstrated that such extended simulations are possible, both for static energy calculations and for dynamical simulations in particular • The quantum mechanical approach is crucial because of strongly varying require- ments to chemical bonding and non-bonded interactions. Corresponding results can serve as reference for even larger classical simulations • These investigations allow the detailed (nanoscale) description of adsorption proc- esses in biogeochemical interfaces at different conditions (pH, humidity, polarity…) • Output of the molecular modeling can be used for parameterization of global models References A.J. A. Aquino, D. Tunega, G. E. Schaumann, G. Haber- hauer, M. H. Gerzabek, and H. Lischka, J. Phys. Chem. C 113, 16468–16475, (2009) D. Tunega, M. H. Gerzabek, G. Haberhauer, K. U. Totsche, and H. Lischka, J. Colloid. & Interface Sci. 330, 244-249, (2009) A.J. A. Aquino, D. Tunega, G. Haberhauer, M. H. Gerza- bek, and H. Lischka Geochim. Cosmochim. Acta 72,3587-3602, (2008) A. J. A. Aquino, D. Tunega, H. Pasalic, G. Haberhauer, M. H. Gerzabek and Hans Lischka Chem. Phys. 349, 69 -76,(2008) 1) Institute for Theoretical Chemistry, University of Vienna, Währinger Straße 17, A -1090 Vienna, Austria; 2) Institute of Soil Research, University of Natural Resources and Ap- plied Life Sciences Vienna, Peter-Jordan-Straße 82, A-1190 Vienna, Austria; 3) Austrian Institute of Technology, A-2444 Seibersdorf, Austria; 4) Center for Radiation Protection and Radioecology, Leibniz Universität Hannover, Herrenhäuser Straße 2, D-30419 Hannover, Germany 5) Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nam. 2 166 10 Prague 6, Czech Republic Water bridges (wet spots) stabilizing Humic Substances Model systems: two carboxyl groups on aliphatic chains connected by a water bridge in different environments Energetic stability diagram n nE n E n E E rel / O H 0 ) ( 2 0 2 4 6 8 10 12 14 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -3.5 -3.0 -2.5 Relative Energy (kcal/mol) Number of H O Connection in acetonitrile Formation of water bridge: in gas phase Experimental adsorption studies MCPA on different soils Destabilization effect of water. Extrapolation to solvent: minimal or no sorption — agreement with experimental observations Bentazone on Montmorillonite: Thermodynamic data for adsorption process at different surface wetting (Force Field Monte Carlo Potential of Mean Force calculations) PAHs interacting with FeO(OH) surfaces Phenanthrene—lepidocrocite -10.3 -4.0 Anthracene—goethite Interaction energy in kcal/mol
Transcript of Interactions of organic pollutants with soil components ...of+organic+poll.... · Interactions of...
Interactions of organic pollutants with soil components – elucidating mechanisms on a molecular level
Adélia J.A. Aquino,1,2 Daniel Tunega,1,2 Hasan Pašalić,1 Georg Haberhauer,3 Ursula Haas,3 Martin H. Gerzabek,2 Ar-tur Meleshyn,4 and Hans Lischka1,5
Recent Achievements
Introduction
Environmental pollution is an important subject as it is one of the major problems of modern society. The chemical pollutants produced imply severe threats for the quality of air, water supplies and soils. Soil organic matter (SOM) is the major pool of active carbon on the Earth and humic materials constitute the leading fraction of SOM. Humic substances (HS) occur widely, exerting a potential influence in soil fer-tility, mineral weathering, and water acidity. They are involved in the transport, sequestration, and mitiga-tion of contaminants being usually thought to be pro-duced from the decomposition of plant and animal residues, having a complex macromolecular struc-ture, a high chemical stability and, on top of it, a strong resistance to microbial degradation. HS play a fundamental role in many biogeochemical processes and in the determination of the properties and behav-ior of many different materials in natural systems. They constitute the most profuse reservoir of carbon on earth and might even have an impact on atmos-pheric chemistry throughout the carbon cycle, in which carbon is continuously recycled amongst plants, animals, soil, air, and water. Owing to the ex-treme complexity of HSs, the modeling of them is very challenging and complicated task. Soil minerals represent another important active com-ponent of soils acting in the formation of stable or-gano-mineral aggregates or in the interactions with various pollutants. These processes are fairly com-plex and their better understanding requires a deep insight on them, even at molecular level using tools of molecular modeling.
Goals
• Improve and develop simulation approaches • Build up realistic theoretical models to reproduce interactions • Determine structural, thermodynamic, and spectroscopic quantities • Evaluate and link theoretical upshots of the modeling to experimental results
Hypothe-
The behavior of organic compounds on the microscale is distinctly influenced by interactions of theses compounds on the nanoscale
Theoretical chemical methods can con-tribute in elucidating the basic processes involved
A. Theoretical
Molecular Modeling Tools:
1. Quantum Mechanics (QM) – DFTB, DFT and MP2 levels
Packages: TURBOMOLE, GAUSSIAN, DFTB+, VASP program packages
2. Molecular Mechanics (MM)- Force-Field parameters for classical potentials
Packages: TINKER, DL_POLY, LAMPPS, AMBER
Structural Models:
1. Oligomeric and polymeric models of humic substances (e.g. polyacrylic acid chains)
2. Cluster and periodic models of soil minerals (montmorillonites, FeO(OH)) 3. Interacting compounds: acetic acid, MCPA, 2,4-dichlorophenol, PAHs, Bentazone
B. Experimental (Isotherms)
Substances: MCPA, Bentazone
Sorbents: Gumpensteiner soil NPK (2.0% OC; pH 5.4) Ca-Montmorillonite (pH 3.2), ferrihydrite, charcoal 3 different artificial soils
Background Solutions: 0.01M CaCl2, 0.01M CaCl2 pH 3 (HCl), 0.1M CaCl2
Methodological Approaches
Exceptional stability of calcium bridges
2.400 2.423
2.362 2.389
2.379 2.420
2.388 2.417
2.393
2.443
2.385 2.371
1.773 1.801
1.859
1.806
2.487
2.34
0
1.6
3
1.699
1.635
1.875
Acknowledgements
Discussion and Contribution to SPPs Grand Goals
• Realistic simulations based on reliable quantum chemical methods have been per-
formed for several interesting problems in soil science
• It has been demonstrated that such extended simulations are possible, both for
static energy calculations and for dynamical simulations in particular
• The quantum mechanical approach is crucial because of strongly varying require-ments to chemical bonding and non-bonded interactions. Corresponding results can
serve as reference for even larger classical simulations
• These investigations allow the detailed (nanoscale) description of adsorption proc-
esses in biogeochemical interfaces at different conditions (pH, humidity, polarity…)
• Output of the molecular modeling can be used for parameterization of global models
References
A.J. A. Aquino, D. Tunega, G. E. Schaumann, G. Haber-hauer, M. H. Gerzabek, and H. Lischka, J. Phys. Chem. C 113, 16468–16475, (2009)
D. Tunega, M. H. Gerzabek, G. Haberhauer, K. U. Totsche, and H. Lischka, J. Colloid. & Interface Sci. 330, 244-249, (2009)
A.J. A. Aquino, D. Tunega, G. Haberhauer, M. H. Gerza-bek, and H. Lischka Geochim. Cosmochim. Acta 72,3587-3602, (2008)
A. J. A. Aquino, D. Tunega, H. Pasalic, G. Haberhauer, M. H. Gerzabek and Hans Lischka Chem. Phys. 349, 69-76,(2008)
1) Institute for Theoretical Chemistry, University of Vienna, Währinger Straße 17, A-1090 Vienna, Austria; 2) Institute of Soil Research, University of Natural Resources and Ap-plied Life Sciences Vienna, Peter-Jordan-Straße 82, A-1190 Vienna, Austria; 3) Austrian Institute of Technology, A-2444 Seibersdorf, Austria; 4) Center for Radiation Protection and Radioecology, Leibniz Universität Hannover, Herrenhäuser Straße 2, D-30419 Hannover, Germany 5) Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nam. 2 166 10 Prague 6, Czech Republic
Water bridges (wet spots) stabilizing Humic Substances
Model systems: two carboxyl groups on aliphatic chains connected by a water bridge in different environments
Energetic stability diagram nnEnEnEErel /OH0)( 2
0 2 4 6 8 10 12 14
-6.5
-6.0
-5.5
-5.0
-4.5
-4.0
-3.5
-3.0
-2.5
Rel
ativ
e E
nerg
y (k
cal/m
ol)
Number of H2O
Connection
in acetonitrile Formation of water bridge: in gas phase
Experimental adsorption studies
MCPA on different soils
Destabilization effect of water. Extrapolation to solvent: minimal or no sorption — agreement with experimental observations
Bentazone on Montmorillonite: Thermodynamic data for adsorption process at different surface wetting (Force Field Monte Carlo Potential of Mean Force calculations)
PAHs interacting with FeO(OH) surfaces
Phenanthrene—lepidocrocite
-10.3
-4.0
Anthracene—goethite
Interaction energy in kcal/mol
