Adsorption of Glutamate on Montmorillonite Clay Surfaces

Abstract

Adsorption of soil organic matter (SOM) to mineral components of soil, particularly clay minerals, is known to play an essential role in the global carbon cycle in addition to influencing pathways of pollutant demobilization. However, uncertainty regarding the composition of SOM complicates efforts to study the adsorptive mechanisms at play within natural systems. Here, organic glutamate is investigated as a simple substitute for complex SOM. The mechanisms controlling the adsorption and aggregation of glutamate on Na+-saturated Montmorillonite clay are explored through X-ray Diffraction (XRD) experiments and Molecular Dynamics (MD) simulations. Density and energetics analyses suggest that favorable Coulomb interactions between clay surfaces and the NH3+ group on glutamate, as well as hydrophobic partitioning, may be the main mechanisms responsible for adsorptive behavior.