Title: Development and application of ReaxFF methodology for understanding the chemical dynamics of metal carbonates in aqueous solutions

Abstract

A new ReaxFF reactive force field has been developed for metal carbonate systems including Na⁺, Ca²⁺, and Mg²⁺ cations and the CO₃^2– anion. This force field is fully transferable with previous ReaxFF water and water/electrolyte descriptions. The Me–O–C (Me = metal) three-body valence angle parameters and Me–C non-reactive parameters of the force field have been optimized against quantum mechanical calculations including equations of state, heats of formation, heats of reaction, angle distortions and vibrational frequencies. The new metal carbonate force field has been validated using molecular dynamics simulations to study the solvation and reactivity of metal and carbonate ions in water at 300 K and 700 K. The coordination radius and self-diffusion coefficient show good consistency with existing experimental and simulation results. The angular distribution analysis explains the structural preference of carbonate ions to form carbonates and bicarbonates, where Na⁺ predominantly forms carbonates due to weaker angular strain, while Ca²⁺ and Mg²⁺ prefer to form bicarbonate monodentate in nature. Residence time distribution analyses on different systems reveal the role of ions in accelerating and decelerating the dynamics of water and carbonate ions under different thermodynamic conditions. The formation and dissolution of bicarbonates and carbonates in solution were explored on themore » basis of the protonation capability in different systems. Here, the nucleation phenomenon of metal carbonates at ambient and supercritical conditions is explained from the perspective of cluster formation over time: Ca²⁺ ions can form prenucleation clusters at ambient temperature but show saturation with increasing temperature, whereas Na⁺ and Mg²⁺ ions show a rapid increase in cluster size and amount upon increasing time and temperature.« less

Authors:

Dasgupta, Nabankur  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5262-6086"

Chen, Chen  ^[1];

• Search DOE PAGES for author "Chen, Chen"
• Search DOE PAGES for ORCID "0000-0002-8316-7898"

van Duin, Adri C. T. ^[1]

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1. Pennsylvania State Univ., University Park, PA (United States)

Publication Date:

Fri Jan 07 00:00:00 EST 2022

Research Org.:

Univ. of Utah, Salt Lake City, UT (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1844392

Alternate Identifier(s):

OSTI ID: 1841449

Grant/Contract Number:  

SC0019285

Resource Type:

Accepted Manuscript

Journal Name:

Physical Chemistry Chemical Physics. PCCP

Additional Journal Information:

Journal Volume: 24; Journal Issue: 5; Journal ID: ISSN 1463-9076

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY