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Title: Real-time observation of cation exchange kinetics and dynamics at the muscovite-water interface

Here, ion exchange at charged solid–liquid interfaces is central to a broad range of chemical and transport phenomena. Real-time observations of adsorption/desorption at the molecular-scale elucidate exchange reaction pathways. Here, we report temporal variation in the distribution of Rb + species at the muscovite (001)–water interface during exchange with Na +. Time-resolved resonant anomalous X-ray reflectivity measurements reveal that Rb + desorption occurs over several tens of seconds during which thermodynamically stable inner-sphere Rb + slowly transforms to less stable outer-sphere Rb + at 25°C. In contrast, Rb + adsorption is about twice as fast, proceeding quickly from Rb + in the bulk solution to the stable inner-sphere species. The Arrhenius plot of the adsorption/desorption rate constants measured from 9 to 55°C shows that the pre-exponential factor for desorption is significantly smaller than for adsorption, indicating that this reduced attempt frequency of cation detachment largely explains the slow cation exchange processes at the interface.
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ;  [3]
  1. Argonne National Lab. (ANL), Argonne, IL (United States)
  2. Univ. of Illinois, Chicago, IL (United States)
  3. Univ. of Delaware, Newark, DE (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22), Chemical Sciences, Geosciences, and Biosciences Division
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; X-ray reflectivity; adsorption; electrical double layer; kinetics; muscovite; geochemistry; reaction kinetics and dynamics; surface chemistry
OSTI Identifier:
1363898