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Title: Organic-Mineral Interfacial Chemistry Drives Heterogeneous Nucleation of Sr-Rich (Bax, Sr1-x)SO4 from Undersaturated Solution

Abstract

Sr-bearing marine barite [(Bax, Sr1-x)SO4] cycling has been widely used to reconstruct geochemical evolutions of paleoenvironments. However, an understanding of barite precipitation in the ocean, which is globally undersaturated with respect to barite, is missing. Moreover, the reason for the occurrence of higher Sr content in marine barites than expected for classical crystal growth processes remains unknown. Field data analyses suggested that organic molecules may regulate the formation and composition of marine barites; however, the specific organic–mineral interactions are unclear. Using in situ grazing incidence small-angle X-ray scattering (GISAXS), size and total volume evolutions of barite precipitates on organic films were characterized. The results show that barite forms on organic films from undersaturated solutions. Moreover, from a single supersaturated solution with respect to barite, Sr-rich barite nanoparticles formed on organics, while micrometer-size Sr-poor barites formed in bulk solutions. Ion adsorption experiments showed that organic films can enrich cation concentrations in the adjacent solution, thus increasing the local supersaturation and promoting barite nucleation on organic films, even when the bulk solution was undersaturated. The Sr enrichment in barites formed on organic films was found to be controlled by solid-solution nucleation rates; instead, the Sr-poor barite formation in bulk solution was foundmore » to be controlled by solid-solution growth rates. This study provides a mechanistic explanation for Sr-rich marine barite formation and offers insights for understanding and controlling the compositions of solid solutions by separately tuning their nucleation and growth rates via the unique chemistry of solution–organic interfaces.« less

Authors:
 [1];  [2];  [2];  [1];  [3];  [1]
  1. University of Houston
  2. Oak Ridge National Laboratory
  3. BATTELLE (PACIFIC NW LAB)
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1566858
Report Number(s):
PNNL-SA-147742
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Proceedings of the National Academy of Sciences (PNAS).
Additional Journal Information:
Journal Volume: 116; Journal Issue: 27
Country of Publication:
United States
Language:
English

Citation Formats

Deng, Ning, Stack, Andrew G., Weber, Juliane, Cao, Bo, De Yoreo, James J., and Hu, Yandi. Organic-Mineral Interfacial Chemistry Drives Heterogeneous Nucleation of Sr-Rich (Bax, Sr1-x)SO4 from Undersaturated Solution. United States: N. p., 2019. Web. doi:10.1073/pnas.1821065116.
Deng, Ning, Stack, Andrew G., Weber, Juliane, Cao, Bo, De Yoreo, James J., & Hu, Yandi. Organic-Mineral Interfacial Chemistry Drives Heterogeneous Nucleation of Sr-Rich (Bax, Sr1-x)SO4 from Undersaturated Solution. United States. doi:10.1073/pnas.1821065116.
Deng, Ning, Stack, Andrew G., Weber, Juliane, Cao, Bo, De Yoreo, James J., and Hu, Yandi. Tue . "Organic-Mineral Interfacial Chemistry Drives Heterogeneous Nucleation of Sr-Rich (Bax, Sr1-x)SO4 from Undersaturated Solution". United States. doi:10.1073/pnas.1821065116.
@article{osti_1566858,
title = {Organic-Mineral Interfacial Chemistry Drives Heterogeneous Nucleation of Sr-Rich (Bax, Sr1-x)SO4 from Undersaturated Solution},
author = {Deng, Ning and Stack, Andrew G. and Weber, Juliane and Cao, Bo and De Yoreo, James J. and Hu, Yandi},
abstractNote = {Sr-bearing marine barite [(Bax, Sr1-x)SO4] cycling has been widely used to reconstruct geochemical evolutions of paleoenvironments. However, an understanding of barite precipitation in the ocean, which is globally undersaturated with respect to barite, is missing. Moreover, the reason for the occurrence of higher Sr content in marine barites than expected for classical crystal growth processes remains unknown. Field data analyses suggested that organic molecules may regulate the formation and composition of marine barites; however, the specific organic–mineral interactions are unclear. Using in situ grazing incidence small-angle X-ray scattering (GISAXS), size and total volume evolutions of barite precipitates on organic films were characterized. The results show that barite forms on organic films from undersaturated solutions. Moreover, from a single supersaturated solution with respect to barite, Sr-rich barite nanoparticles formed on organics, while micrometer-size Sr-poor barites formed in bulk solutions. Ion adsorption experiments showed that organic films can enrich cation concentrations in the adjacent solution, thus increasing the local supersaturation and promoting barite nucleation on organic films, even when the bulk solution was undersaturated. The Sr enrichment in barites formed on organic films was found to be controlled by solid-solution nucleation rates; instead, the Sr-poor barite formation in bulk solution was found to be controlled by solid-solution growth rates. This study provides a mechanistic explanation for Sr-rich marine barite formation and offers insights for understanding and controlling the compositions of solid solutions by separately tuning their nucleation and growth rates via the unique chemistry of solution–organic interfaces.},
doi = {10.1073/pnas.1821065116},
journal = {Proceedings of the National Academy of Sciences (PNAS).},
number = 27,
volume = 116,
place = {United States},
year = {2019},
month = {7}
}

Works referenced in this record:

X-Ray Interactions: Photoabsorption, Scattering, Transmission, and Reflection at E = 50-30,000 eV, Z = 1-92
journal, July 1993

  • Henke, B. L.; Gullikson, E. M.; Davis, J. C.
  • Atomic Data and Nuclear Data Tables, Vol. 54, Issue 2, p. 181-342
  • DOI: 10.1006/adnd.1993.1013