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Title: Interaction of NaOH solutions with silica surfaces

Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na + ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m 2 (0.01 M NaOH) and –0.76 C/m 2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate, and tridentate configurations and two additional structures, with Na + ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na + ions by bridging oxygen atoms indicates partial or complete incorporation of Na + ions into the silica surface. Residence time analysis identified that Na + ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na + ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na + adsorption and lifetimes have implications formore » the stability of silica surfaces.« less
Authors:
 [1] ;  [2] ;  [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Report Number(s):
SAND-2018-1338J
Journal ID: ISSN 0021-9797; 660557
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Journal of Colloid and Interface Science
Additional Journal Information:
Journal Volume: 516; Journal Issue: C; Journal ID: ISSN 0021-9797
Publisher:
Elsevier
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Adsorption; Silica; Molecular simulations; NaOH; Molecular dynamics
OSTI Identifier:
1421767

Rimsza, Jessica M., Jones, Reese E., and Criscenti, Louise J.. Interaction of NaOH solutions with silica surfaces. United States: N. p., Web. doi:10.1016/j.jcis.2018.01.049.
Rimsza, Jessica M., Jones, Reese E., & Criscenti, Louise J.. Interaction of NaOH solutions with silica surfaces. United States. doi:10.1016/j.jcis.2018.01.049.
Rimsza, Jessica M., Jones, Reese E., and Criscenti, Louise J.. 2018. "Interaction of NaOH solutions with silica surfaces". United States. doi:10.1016/j.jcis.2018.01.049.
@article{osti_1421767,
title = {Interaction of NaOH solutions with silica surfaces},
author = {Rimsza, Jessica M. and Jones, Reese E. and Criscenti, Louise J.},
abstractNote = {Sodium adsorption on silica surfaces depends on the solution counter-ion. Here, we use NaOH solutions to investigate basic environments. Sodium adsorption on hydroxylated silica surfaces from NaOH solutions were investigated through molecular dynamics with a dissociative force field, allowing for the development of secondary molecular species. Furthermore, across the NaOH concentrations (0.01 M – 1.0 M), ~50% of the Na+ ions were concentrated in the surface region, developing silica surface charges between –0.01 C/m2 (0.01 M NaOH) and –0.76 C/m2 (1.0 M NaOH) due to surface site deprotonation. Five inner-sphere adsorption complexes were identified, including monodentate, bidentate, and tridentate configurations and two additional structures, with Na+ ions coordinated by bridging oxygen and hydroxyl groups or water molecules. Coordination of Na+ ions by bridging oxygen atoms indicates partial or complete incorporation of Na+ ions into the silica surface. Residence time analysis identified that Na+ ions coordinated by bridging oxygen atoms stayed adsorbed onto the surface four times longer than the mono/bi/tridentate species, indicating formation of relatively stable and persistent Na+ ion adsorption structures. Such inner-sphere complexes form only at NaOH concentrations of > 0.5 M. Na+ adsorption and lifetimes have implications for the stability of silica surfaces.},
doi = {10.1016/j.jcis.2018.01.049},
journal = {Journal of Colloid and Interface Science},
number = C,
volume = 516,
place = {United States},
year = {2018},
month = {1}
}