Spatial Arrangment of Organic Compounds on a Model Mineral Surface: Implications for Soil Organic Matter Stabilization

Journal Article · Tue Dec 31 23:00:00 EST 2013 · Environmental Science & Technology

DOI:https://doi.org/10.1021/es403430k· OSTI ID:1185412

Petridis, Loukas ^[1]; Ambaye, Haile Arena ^[1]; Jagadamma, Sindhu ^[1]; Kilbey, S. Michael ^[2]; Lokitz, Bradley S ^[1]; Lauter, Valeria ^[1]; Mayes, Melanie ^[1]

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1. ORNL
2. University of Tennessee, Knoxville (UTK)

The complexity of the mineral organic carbon interface may influence the extent of stabilization of organic carbon compounds in soils, which is important for global climate futures. The nanoscale structure of a model interface was examined here by depositing films of organic carbon compounds of contrasting chemical character, hydrophilic glucose and amphiphilic stearic acid, onto a soil mineral analogue (Al2O3). Neutron reflectometry, a technique which provides depth-sensitive insight into the organization of the thin films, indicates that glucose molecules reside in a layer between Al2O3 and stearic acid, a result that was verified by water contact angle measurements. Molecular dynamics simulations reveal the thermodynamic driving force behind glucose partitioning on the mineral interface: The entropic penalty of confining the less mobile glucose on the mineral surface is lower than for stearic acid. The fundamental information obtained here helps rationalize how complex arrangements of organic carbon on soil mineral surfaces may arise

• Research Organization: Oak Ridge National Laboratory (ORNL); Center for Nanophase Materials Sciences (CNMS); Spallation Neutron Source
• Sponsoring Organization: ORNL Program Development
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1185412
• Journal Information: Environmental Science & Technology, Journal Name: Environmental Science & Technology Journal Issue: 1 Vol. 48; ISSN 0013-936X
• Country of Publication: United States
• Language: English