Probing the aluminum complexation by Siberian riverine organic matter using solid-state DNP-NMR
International audience In a Siberian river, the concentrations of chemical species vary with the hydrological regime. Dissolved Organic Matter (DOM) and aluminum ions show a parallel trend in the course of the hydrological year. However, the speciation of aluminum in this natural environment remains...
Published in: | Chemical Geology |
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Main Authors: | , , , , , , , , , , , |
Other Authors: | , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2017
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Subjects: | |
Online Access: | https://hal.science/hal-01507396 https://doi.org/10.1016/j.chemgeo.2017.02.004 |
Summary: | International audience In a Siberian river, the concentrations of chemical species vary with the hydrological regime. Dissolved Organic Matter (DOM) and aluminum ions show a parallel trend in the course of the hydrological year. However, the speciation of aluminum in this natural environment remains an open question. We propose here a combination of spectroscopic techniques to investigate the proximity between the aluminum atoms and DOM. First, one-dimensional (1D) solid-state Nuclear Magnetic Resonance (NMR), Electron Paramagnetic Resonance (EPR) and 1D and 2D solution NMR spectra were acquired, providing a clear overview of the DOM composition. Second, the sensitivity enhancement yielded by Dynamic Nuclear Polarization enabled the NMR detection of proximities between the 27 Al and 13 C nuclei. Hence, we show that 8.3 ± 1.3% of the carboxylate groups observed by NMR are connected to the Al 3+ ions in the DOM sample. We here demonstrate for the first time how advanced solid-state NMR methods can provide key information about the localization of aluminum in such complex natural materials. |
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