Abstract
For the majority of the water present on earth, the two most important factors influencing its behavior are confinement, in either inorganic or organic matrixes, and the presence of solutes. Here, we investigate the effect of confinement in 3 nm pores on water diffusivity in aqueous solutions with archetypical solutes, a structure making (kosmotrope) NaCl and a structure breaking (chaotrope) KCl, up to 1.0 M in concentration. The water diffusivity in bulk aqueous solutions in such a concentration range is known to decrease very slightly in the presence of NaCl and increase very slightly in the presence of KCl. However, here we observe the water diffusivity in confined H2O-KCl increases by a factor of 2 compared to the pure water diffusivity in the same confinement. This unusually strong cumulative effect of confinement and a structure breaking additive may have profound implications for the mobility and transport of aqueous species in nature.
| Original language | English |
|---|---|
| Pages (from-to) | 4038-4044 |
| Number of pages | 7 |
| Journal | Journal of Physical Chemistry Letters |
| Volume | 12 |
| Issue number | 16 |
| DOIs | |
| State | Published - Apr 29 2021 |
Funding
This work was supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Work at ORNL’s Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for U.S. DOE under Contract No. DEAC05-00OR22725. QClimax is a part of the Integrated Computational Environment Modeling and Analysis of Neutron Data (ICE-MAN) (LDRD 8237) project, funded by the Laboratory Directed Research and Development program at ORNL. Access to the HFBS was provided by the center of High Resolution Neutron Scattering, a partnership between the NIST and the National Science Foundation under Agreement No. DMR-1508249. Certain commercial material suppliers are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.
| Funders | Funder number |
|---|---|
| Scientific User Facilities Division | |
| National Science Foundation | DMR-1508249 |
| U.S. Department of Energy | LDRD 8237, DEAC05-00OR22725 |
| National Institute of Standards and Technology | |
| Office of Science | |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| Laboratory Directed Research and Development |