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Ab Initio Molecular Dynamics Simulations of the Interaction between Organic Phosphates and Goethite

preprint
submitted on 12.11.2020, 10:25 and posted on 16.11.2020, 05:10 by Prasanth Babu Ganta, Oliver Kühn, Ashour A. Ahmed
Today's fertilizers rely heavily on mining phosphorus (P) rocks. These rocks are known to become exhausted in near future and hence, effective P use is crucial to avoid food shortage. A substantial amount of P from fertilizers gets adsorbed onto soil minerals to become unavailable to plants. Understanding P interaction with these minerals would help efforts that improve P efficiency. To this end we performed a molecular level analysis of the interaction of common organic P compounds (glycerolphosphate [GP] & inositol hexaphosphate [IHP]) with the abundant soil mineral (goethite) in presence of water. Molecular dynamics simulations are performed for goethite-IHP/GP-water complexes using the multiscale quantum mechanics/molecular mechanics method. Results show that GP forms monodentate (M) and bidentate mononuclear (B) motifs with B being more stable than M. IHP interacts through multiple phosphate groups with the \textbf{3M} motif being most stable. The order of goethite-IHP/GP interaction energies is: GP M < GP B < IHP M < IHP 3M. Water is important in these interactions as multiple proton transfers occur and hydrogen bonds are formed between goethite--IHP/GP complexes and water. We also present theoretically calculated infrared spectra which match reasonably well with frequencies reported in literature.

Funding

Deutsche Forschungsgemeinschaft

BMBF (InnoSoilPhos)

History

Email Address of Submitting Author

oliver.kuehn@uni-rostock.de

Institution

University of Rostock, Institute of Physics

Country

Germany

ORCID For Submitting Author

0000-0002-5933-5249

Declaration of Conflict of Interest

none

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