Fundamental studies of the sorption of organic molecules within engineered soil surrogates
EMSL Project ID
49814
Abstract
The sorption of molecules into the organic matrix of soils (a.k.a soil organic matter [SOM]) is of great importance for a number of environmental issues; in particular 1) carbon cycling via carbon sequestration and 2) fate and transport of organic pollutants. To fully understand and model these two issues, a molecular level understanding of the sorption processes in SOM is needed. SOM makes this a very daunting task due to its extremely complex and heterogeneous nature. In order to approach such a complex and heterogeneous system, one can take a few steps back and develop simplified surrogates that mimic the complexity and heterogeneous nature of real soils while, at the same time, allow for advance molecular level analysis to be performed, processed, and modeled. In this proposal, advanced solid state NMR techniques, available via EMSL NMR resources, will be used to analyze the sorption of model sorbates to model sorbents. The sorbents will be engineered soil surrogates with increasingly more complex and heterogeneous organic surface coatings. The composition of the sorbents organic coatings will echo that of SOM. The sorbates will be a range of probes, ranging in terms of functional groups and polarity. The sorbed sorbates will be interrogated with a number of 1D methods in order to 1) quantify the amount of sorbate sorbed (via spin counting), 2) determine the mobility of the sorbate (via correlation time), and 3) find out the chemical environment of the sorbate (via chemical shift). Subsequently, molecular level interactions will be studied by a combination of double resonance NMR techniques, which take advantage of dipolar interactions. In all cases, the obtained results will be compared to sorption isotherm data on the same sorbate and sorbent systems, in order to associate molecular level understanding with large bulk scale sorption data. It is important to note that these systems and approach are scalable and hence can be built on in regards to complexity and heterogeneity, which is very important as a number of scaling steps will be needed in order to start address real soils.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2017-10-01
End Date
2019-09-30
Status
Closed
Released Data Link
Team
Principal Investigator