skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal

Abstract

Here, we use large-scale molecular dynamics simulations coupled to free energy calculations to identify for the first time a limit of stability (spinodal) and a change in the nucleation mechanism in aqueous NaCl solutions. This is a system of considerable atmospheric, geological, and technical significance. We find that the supersaturated metastable NaCl solution reaches its limit of stability at sufficiently high salt concentrations, as indicated by the composition dependence of the salt chemical potential, indicating the transition to a phase separation by spinodal decomposition. However, the metastability limit of the NaCl solution does not correspond to spinodal decomposition with respect to crystallization. We find that beyond this spinodal, a liquid/amorphous separation occurs in the aqueous solution, whereby the ions first form disordered clusters. We term these clusters as “amorphous salt.” We also identify a transition from one- to two-step crystallization mechanism driven by a spinodal. In particular, crystallization from aqueous NaCl solution beyond the spinodal is a two-step process, in which the ions first phase-separate into disordered amorphous salt clusters, followed by the crystallization of ions in the amorphous salt phase. By contrast, in the aqueous NaCl solution at concentrations lower than the spinodal, crystallization occurs via a one-step processmore » as the ions aggregate directly into crystalline nuclei. The change of mechanism with increasing supersaturation underscores the importance of an accurate determination of the driving force for phase separation. The study has broader implications on the mechanism for nucleation of crystals from solutions at high supersaturations.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [2]
  1. Univ. of Pennsylvania, Philadelphia, PA (United States)
  2. Princeton Univ., NJ (United States)
Publication Date:
Research Org.:
Princeton Univ., NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
OSTI Identifier:
1610630
Alternate Identifier(s):
OSTI ID: 1503939
Grant/Contract Number:  
SC0002128
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 150; Journal Issue: 12; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; chemistry; physics

Citation Formats

Jiang, Hao, Debenedetti, Pablo G., and Panagiotopoulos, Athanassios Z. Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal. United States: N. p., 2019. Web. doi:10.1063/1.5084248.
Jiang, Hao, Debenedetti, Pablo G., & Panagiotopoulos, Athanassios Z. Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal. United States. https://doi.org/10.1063/1.5084248
Jiang, Hao, Debenedetti, Pablo G., and Panagiotopoulos, Athanassios Z. Fri . "Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal". United States. https://doi.org/10.1063/1.5084248. https://www.osti.gov/servlets/purl/1610630.
@article{osti_1610630,
title = {Nucleation in aqueous NaCl solutions shifts from 1-step to 2-step mechanism on crossing the spinodal},
author = {Jiang, Hao and Debenedetti, Pablo G. and Panagiotopoulos, Athanassios Z.},
abstractNote = {Here, we use large-scale molecular dynamics simulations coupled to free energy calculations to identify for the first time a limit of stability (spinodal) and a change in the nucleation mechanism in aqueous NaCl solutions. This is a system of considerable atmospheric, geological, and technical significance. We find that the supersaturated metastable NaCl solution reaches its limit of stability at sufficiently high salt concentrations, as indicated by the composition dependence of the salt chemical potential, indicating the transition to a phase separation by spinodal decomposition. However, the metastability limit of the NaCl solution does not correspond to spinodal decomposition with respect to crystallization. We find that beyond this spinodal, a liquid/amorphous separation occurs in the aqueous solution, whereby the ions first form disordered clusters. We term these clusters as “amorphous salt.” We also identify a transition from one- to two-step crystallization mechanism driven by a spinodal. In particular, crystallization from aqueous NaCl solution beyond the spinodal is a two-step process, in which the ions first phase-separate into disordered amorphous salt clusters, followed by the crystallization of ions in the amorphous salt phase. By contrast, in the aqueous NaCl solution at concentrations lower than the spinodal, crystallization occurs via a one-step process as the ions aggregate directly into crystalline nuclei. The change of mechanism with increasing supersaturation underscores the importance of an accurate determination of the driving force for phase separation. The study has broader implications on the mechanism for nucleation of crystals from solutions at high supersaturations.},
doi = {10.1063/1.5084248},
url = {https://www.osti.gov/biblio/1610630}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 12,
volume = 150,
place = {United States},
year = {2019},
month = {3}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 9 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

A Molecular Dynamics Study of the Early Stages of Calcium Carbonate Growth
journal, August 2009


Nucleation of NaCl from Aqueous Solution: Critical Sizes, Ion-Attachment Kinetics, and Rates
journal, October 2015


Molecular simulation of thermodynamic and transport properties for the H 2 O+NaCl system
journal, December 2014


Nucleation of Crystals from Solution: Classical and Two-Step Models
journal, May 2009


Temperature-dependent formation of NaCl dihydrate in levitated NaCl and sea salt aerosol particles
journal, December 2016


Nucleation barriers in tetrahedral liquids spanning glassy and crystallizing regimes
journal, September 2011


Amorphous precursors of crystallization during spinodal decomposition
journal, February 2011


A simulation study of homogeneous ice nucleation in supercooled salty water
journal, June 2018


Communication: Nucleation rates of supersaturated aqueous NaCl using a polarizable force field
journal, October 2018


Thermodynamic properties of a symmetrical binary mixture in the coexistence region
journal, December 2011


Numerical prediction of absolute crystallization rates in hard-sphere colloids
journal, February 2004


Microscopic Evidence for Liquid-Liquid Separation in Supersaturated CaCO3 Solutions
journal, August 2013


New method to analyze simulations of activated processes
journal, April 2007


Mean ionic activity coefficients in aqueous NaCl solutions from molecular dynamics simulations
journal, January 2015


Recent progress in molecular simulation of aqueous electrolytes: force fields, chemical potentials and solubility
journal, March 2016


NaCl nucleation from brine in seeded simulations: Sources of uncertainty in rate estimates
journal, June 2018


Nucleation from Solution
journal, August 2013


Direct calculation of ice homogeneous nucleation rate for a molecular model of water
journal, August 2015


Phase transitions in fluctuations and their role in two-step nucleation
journal, February 2019


Molecular-dynamics simulations of urea nucleation from aqueous solution
journal, December 2014


Interplay between two phase transitions: Crystallization and liquid-liquid phase separation in a polyolefin blend
journal, July 2006


A Review of Classical and Nonclassical Nucleation Theories
journal, October 2016


Stable prenucleation mineral clusters are liquid-like ionic polymers
journal, September 2011


More than one pathway
journal, March 2013


On the calculation of solubilities via direct coexistence simulations: Investigation of NaCl aqueous solutions and Lennard-Jones binary mixtures
journal, October 2016


Crystallization of a binary Lennard-Jones mixture
journal, March 2011


Theory of spinodal decomposition assisted crystallization in binary mixtures
journal, May 2010


Solution crystallisation via a submerged liquid–liquid phase boundary: oiling out
journal, February 2003


The evaporation/condensation transition of liquid droplets
journal, March 2004


In situ observations of liquid–liquid phase separation in aqueous MgSO4 solutions: Geological and geochemical implications
journal, February 2013


Forward flux sampling calculation of homogeneous nucleation rates from aqueous NaCl solutions
journal, January 2018


Multistep nucleation of nanocrystals in aqueous solution
journal, October 2016


Statistical theory of nucleation, condensation and coagulation
journal, July 1976


Crystal Nucleation in Liquids: Open Questions and Future Challenges in Molecular Dynamics Simulations
journal, May 2016


Crystallization of Lennard-Jones nanodroplets: From near melting to deeply supercooled
journal, March 2015


Hybrid Monte Carlo with LAMMPS
journal, May 2018


How Crystals Nucleate and Grow in Aqueous NaCl Solution
journal, January 2013


Enhancement of Protein Crystal Nucleation by Critical Density Fluctuations
journal, September 1997


Temperature-dependent solubilities and mean ionic activity coefficients of alkali halides in water from molecular dynamics simulations
journal, July 2015


Birth of NaCl Crystals: Insights from Molecular Simulations
journal, August 2016


Bond-orientational order in liquids and glasses
journal, July 1983


Deposition of calcium carbonate films by a polymer-induced liquid-precursor (PILP) process
journal, March 2000


Promotion of Homogeneous Ice Nucleation by Soluble Molecules
journal, November 2017


Kinetic Reconstruction of the Free-Energy Landscape
journal, September 2008


Simulations of the nucleation of AgBr from solution
journal, October 2000


Phase Diagram of Colloidal Solutions
journal, December 1996


The two-step mechanism of nucleation of crystals in solution
journal, January 2010


The thermodynamics of calcite nucleation at organic interfaces: Classical vs. non-classical pathways
journal, January 2012


Frustration vs Prenucleation: Understanding the Surprising Stability of Supersaturated Sodium Thiosulfate Solutions
journal, July 2018


Microscopic Mechanism and Kinetics of Ice Formation at Complex Interfaces: Zooming in on Kaolinite
journal, June 2016


Salt Crystallization from an Evaporating Aqueous Solution by Molecular Dynamics Simulations
journal, August 2003


The influence of ion hydration on nucleation and growth of LiF crystals in aqueous solution
journal, January 2018


Molecular Simulation of Aqueous Electrolyte Solubility. 3. Alkali-Halide Salts and Their Mixtures in Water and in Hydrochloric Acid
journal, April 2012


Computer Simulation of Crystallization from Solution
journal, September 1998


Molecular force fields for aqueous electrolytes: SPC/E-compatible charged LJ sphere models and their limitations
journal, April 2013


Determination of Alkali and Halide Monovalent Ion Parameters for Use in Explicitly Solvated Biomolecular Simulations
journal, July 2008


Urea homogeneous nucleation mechanism is solvent dependent
journal, January 2015


Observing classical nucleation theory at work by monitoring phase transitions with molecular precision
journal, December 2014


A metastable liquid precursor phase of calcium carbonate and its interactions with polyaspartate
journal, January 2012


The missing term in effective pair potentials
journal, November 1987


Test of classical nucleation theory and mean first-passage time formalism on crystallization in the Lennard-Jones liquid
journal, January 2009


    Works referencing / citing this record:

    Entropic colloidal crystallization pathways via fluid–fluid transitions and multidimensional prenucleation motifs
    journal, July 2019