Ion exchange in nanoporous clay-rich media plays an integral role in water, nutrient, and contaminant storage and transport. In montmorillonite (MMT), a common clay mineral in soils, sediments, and muds, the swelling and collapse of clay particles through the addition or removal of discrete molecular layers of water alters cation exchange selectivities in a poorly understood way. Here, we show that ion exchange is coupled to the dynamic delamination and restacking of clay layers, which creates a feedback between the hydration state of the exchanging cation and the composition of the clay interlayer. Particles with different hydration states are distinct phases with unique binding selectivities. Surprisingly, equilibrium achieved through thermal fluctuations in cation concentration and hydration state leads to the exchange of both ions and individual MMT layers between particles, a process we image directly with high-resolution transmission electron microscopy at cryogenic conditions (cryo-TEM). We introduce an exchange model that accounts for the binding selectivities of different phases, which is likely applicable to many charged colloidal or macromolecular systems in which the structural conformation is correlated with the activities of water and counterions within spatially confined compartments.
Whittaker, Michael L., et al. "Ion exchange selectivity in clay is controlled by nanoscale chemical–mechanical coupling." Proceedings of the National Academy of Sciences of the United States of America, vol. 116, no. 44, Oct. 2019. https://doi.org/10.1073/pnas.1908086116
Whittaker, Michael L., Lammers, Laura N., Carrero, Sergio, Gilbert, Benjamin, & Banfield, Jillian F. (2019). Ion exchange selectivity in clay is controlled by nanoscale chemical–mechanical coupling. Proceedings of the National Academy of Sciences of the United States of America, 116(44). https://doi.org/10.1073/pnas.1908086116
Whittaker, Michael L., Lammers, Laura N., Carrero, Sergio, et al., "Ion exchange selectivity in clay is controlled by nanoscale chemical–mechanical coupling," Proceedings of the National Academy of Sciences of the United States of America 116, no. 44 (2019), https://doi.org/10.1073/pnas.1908086116
@article{osti_1570769,
author = {Whittaker, Michael L. and Lammers, Laura N. and Carrero, Sergio and Gilbert, Benjamin and Banfield, Jillian F.},
title = {Ion exchange selectivity in clay is controlled by nanoscale chemical–mechanical coupling},
annote = {Ion exchange in nanoporous clay-rich media plays an integral role in water, nutrient, and contaminant storage and transport. In montmorillonite (MMT), a common clay mineral in soils, sediments, and muds, the swelling and collapse of clay particles through the addition or removal of discrete molecular layers of water alters cation exchange selectivities in a poorly understood way. Here, we show that ion exchange is coupled to the dynamic delamination and restacking of clay layers, which creates a feedback between the hydration state of the exchanging cation and the composition of the clay interlayer. Particles with different hydration states are distinct phases with unique binding selectivities. Surprisingly, equilibrium achieved through thermal fluctuations in cation concentration and hydration state leads to the exchange of both ions and individual MMT layers between particles, a process we image directly with high-resolution transmission electron microscopy at cryogenic conditions (cryo-TEM). We introduce an exchange model that accounts for the binding selectivities of different phases, which is likely applicable to many charged colloidal or macromolecular systems in which the structural conformation is correlated with the activities of water and counterions within spatially confined compartments.},
doi = {10.1073/pnas.1908086116},
url = {https://www.osti.gov/biblio/1570769},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
issn = {ISSN 0027-8424},
number = {44},
volume = {116},
place = {United States},
publisher = {National Academy of Sciences},
year = {2019},
month = {10}}
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
National Science Foundation (NSF); USDOE; USDOE Office of Science (SC)
Grant/Contract Number:
AC02-05CH11231; AC02-06CH11357
OSTI ID:
1570769
Alternate ID(s):
OSTI ID: 1575020 OSTI ID: 1581755
Journal Information:
Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 44 Vol. 116; ISSN 0027-8424
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 649, Issue 1https://doi.org/10.1016/j.nima.2010.12.045