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Title: Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba 2+ Adsorption

Barium sulfate (BaSO 4) is a common scale-forming mineral in natural and engineered systems, yet the rates and mechanisms of heterogeneous BaSO 4 nucleation are not understood. To address these, we created idealized interfaces on which to study heterogeneous nucleation rates and mechanisms, which also are good models for organic–water interfaces: self-assembled thin films terminated with different functional groups (i.e., -COOH, -SH, or mixed -SH & COOH) coated on glass slides. BaSO4 precipitation on coatings from Barite-supersaturated solutions (saturation index, SI, = 1.1) was investigated using grazing-incidence small-angle X-ray scattering. After reaction for 1 h, a little amount of BaSO4 formed on hydrophilic bare and -COOH coated glasses. Meanwhile, BaSO4 nucleation was significantly promoted on hydrophobic -SH and mixed -SH & COOH coatings. This is because substrate hydrophobicity likely affected the interfacial energy and hence thermodynamic favorability of heterogeneous nucleation. The heterogeneous BaSO 4 nucleation and growth kinetics were found to be affected by the amount of Ba 2+ adsorption onto the substrate and incipient BaSO 4 nuclei. The importance of Ba 2+ adsorption was further corroborated by the finding that precipitation rate increased under [Ba 2+]/[SO 4 2–] concentration ratios >1. These observations suggest that thermodynamic favorability for nucleationmore » is governed by substrate–water interfacial energy, while given favorable thermodynamics, the rate is governed by ion attachment to substrates and incipient nuclei.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1]
  1. Univ. of Houston, Houston, TX (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Univ. Grenoble Alpes, Grenoble (France)
  4. Univ. Grenoble Alpes, Grenoble (France); Centre National de la Recherche Scientifique (CNRS), Grenoble (France)
  5. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 32; Journal Issue: 21; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1346634

Dai, Chong, Stack, Andrew G., Koishi, Ayumi, Fernandez-Martinez, Alejandro, Lee, Sang Soo, and Hu, Yandi. Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba2+ Adsorption. United States: N. p., Web. doi:10.1021/acs.langmuir.6b01036.
Dai, Chong, Stack, Andrew G., Koishi, Ayumi, Fernandez-Martinez, Alejandro, Lee, Sang Soo, & Hu, Yandi. Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba2+ Adsorption. United States. doi:10.1021/acs.langmuir.6b01036.
Dai, Chong, Stack, Andrew G., Koishi, Ayumi, Fernandez-Martinez, Alejandro, Lee, Sang Soo, and Hu, Yandi. 2016. "Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba2+ Adsorption". United States. doi:10.1021/acs.langmuir.6b01036. https://www.osti.gov/servlets/purl/1346634.
@article{osti_1346634,
title = {Heterogeneous Nucleation and Growth of Barium Sulfate at Organic-Water Interfaces: Interplay between Surface Hydrophobicity and Ba2+ Adsorption},
author = {Dai, Chong and Stack, Andrew G. and Koishi, Ayumi and Fernandez-Martinez, Alejandro and Lee, Sang Soo and Hu, Yandi},
abstractNote = {Barium sulfate (BaSO4) is a common scale-forming mineral in natural and engineered systems, yet the rates and mechanisms of heterogeneous BaSO4 nucleation are not understood. To address these, we created idealized interfaces on which to study heterogeneous nucleation rates and mechanisms, which also are good models for organic–water interfaces: self-assembled thin films terminated with different functional groups (i.e., -COOH, -SH, or mixed -SH & COOH) coated on glass slides. BaSO4 precipitation on coatings from Barite-supersaturated solutions (saturation index, SI, = 1.1) was investigated using grazing-incidence small-angle X-ray scattering. After reaction for 1 h, a little amount of BaSO4 formed on hydrophilic bare and -COOH coated glasses. Meanwhile, BaSO4 nucleation was significantly promoted on hydrophobic -SH and mixed -SH & COOH coatings. This is because substrate hydrophobicity likely affected the interfacial energy and hence thermodynamic favorability of heterogeneous nucleation. The heterogeneous BaSO4 nucleation and growth kinetics were found to be affected by the amount of Ba2+ adsorption onto the substrate and incipient BaSO4 nuclei. The importance of Ba2+ adsorption was further corroborated by the finding that precipitation rate increased under [Ba2+]/[SO42–] concentration ratios >1. These observations suggest that thermodynamic favorability for nucleation is governed by substrate–water interfacial energy, while given favorable thermodynamics, the rate is governed by ion attachment to substrates and incipient nuclei.},
doi = {10.1021/acs.langmuir.6b01036},
journal = {Langmuir},
number = 21,
volume = 32,
place = {United States},
year = {2016},
month = {5}
}