Molecular simulation of aqueous and non-aqueous electrolyte - - PowerPoint PPT Presentation

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Molecular simulation of aqueous and non-aqueous electrolyte - - PowerPoint PPT Presentation

Sep 26, 2022 253 likes •433 views

Laboratory of Engineering Thermodynamics Prof. Dr.-Ing. H. Hasse AIChE Annual Meeting, San Francisco, 4 th November 13 Molecular simulation of aqueous and non-aqueous electrolyte solutions M. T. Horsch, 1 S. Reiser, 1 S. Deublein, 1 J. Vrabec,

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SLIDE 1

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Molecular simulation of aqueous and non-aqueous electrolyte solutions

  • M. T. Horsch,1 S. Reiser,1 S. Deublein,1 J. Vrabec,2 and H. Hasse1

AIChE Annual Meeting, San Francisco, 4th November 13

1 Laboratory of Engineering Thermodynamics, University of Kaiserslautern, Germany 2 Thermodynamics and Energy Technology, University of Paderborn, Germany

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SLIDE 2

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

2

Electrolyte Solutions – Applications

Buffer solutions in pharmaceutical and biochemical industry / purification of proteins Electrochemistry / energy storages

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 3

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Literature models:

  • Scattering of model parameters

Reference property:

  • Density ρ

Ions 1 CLJ 1 point charge

  • Simulation of aqueous electrolyte solution

3

Molecular models: Water 1 CLJ 3 partial charges

+ +

  • Parameters Na+ :

1.9 < σNa+ / Å < 4.1 0.06 < εNa+ / K < 1068.8 Large deviation from experiments

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 4

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

4

Adjustable parameters:

  • Ions: 1 CLJ with 1 point charge (±1e) – 2 parameters

Parameter optimization for alkali halides

  • σIon, εIon

Target:

  • Reduced density for varying salinity at T = 293 K, p = 1 bar

Electrolyte solution Solvent

( , , , , )   x ρ ρ ρ σ σ ε ε ρ

+ − + − ±

= =

Simulation conditions:

  • Monte Carlo simulation
  • SPC/E water model
  • Simulation code: extended version of ms2*

*Deublein et al., Computer Physics Communications (2011), 182, 2350 – 2367; http://www.ms-2.de

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 5

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Adjustment:

5

Target: Slope of the reduced density over the salt mass fraction

Sim Sim +

  • (m)

(m)

d d ( , ) d d   m x x ρ ρ σ σ = = m

Sim

 ρ

Sim Sim +

  • (

, , )   x ρ ρ σ σ

±

=

Reduced density of NaCl solutions (T = 298 K, p = 1 bar) Sensitivity study of :

  • σIon dominant
  • εIon negligible

ε = 0.25εCl ε = 4εCl

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 6

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

6

Parameter optimization for alkali halides

Electrolyte systems: 5 cations: Li+, Na+, K+, Rb+, Cs+ 4 anions: F-, Cl-, Br-, I- 20 salts modeled by 9 parameter

Exp Sim +

  • (m)

(m)

! d d ( , ) d d   x x ρ ρ σ σ = Size adjustment:

  • Global fit

σ+[1.5; 4.5] Å σ- [2.0; 4.5] Å

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 7

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

7

σLi = 1.88 Å σNa = 1.89 Å σK = 2.77 Å σRb = 3.26 Å σCs = 3.58 Å

Anions

σF = 3.66 Å σCl = 4.41 Å σBr = 4.54 Å σI = 4.78 Å

Aqueous electrolyte solutions

Reduced density (T = 293 K, p = 1 bar)

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 8

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse
  • Reasonable parameter

range: 200 K ≤ εBr- ≤ 400 K

Self-diffusion coefficient of ions in aqueous solution (Example bromide)

8

  • Similar dependence of

Di on εi for all alkali and halide ions Adjustment of the LJ energy parameters εIon to the self- diffusion coefficient in solution (T = 298 K, p = 1 bar) Water model: SPC/E

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 9

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse
  • Reasonable match:

εBr- = 200 K

Radial distribution function of water around the ions (Example bromide)

9

Adjustment of the LJ energy parameters εIon to the first maximum rmax,1 in the RDF (T = 293 K, p = 1 bar) Water model: SPC/E

  • Best choice:

ε+ = ε- = 200 K

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 10

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Self-diffusion coefficient of alkali cations and halide anions in aqueous solution

10

Comparison with experimental data (T = 298 K, p = 1 bar) Water model: SPC/E Cations Anions

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 11

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Electric conductivity of NaCl and CsCl in aqueous solutions at various salinities

11

Water model: SPC/E Electric conductivity:

  • Correlated motion of the

ions in solution Predictions (T = 298 K, p = 1 bar)

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 12

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse
  • Experimental

data (this work)

  • Simulation

12

Temperature dependence of the density

Predictions for aqueous solution (T = 333 K, p = 1 bar)

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 13

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Ions 1 CLJ 1 point charge

  • Simulation of non-aqueous electrolyte

solutions: solvent methanol

13

Methanol 2 CLJ 3 partial charges Reference property:

  • Reduced density
  • +

+

Molecular models:

Electrolyt solution Solvent

 ρ ρ ρ =

Simulation:

  • MC simulations at T = 298 K, p = 1 bar

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 14

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

Methanolic electrolyte solutions

14

Predictions (T = 298 K, p = 1 bar)

  • Experimental

data (this work)

  • Simulation

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 15

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse
  • r1. Max / Å
  • r1. Min / Å

Methanol Water Methanol Water Na – O 2.21 2.23 3.17 3.07

15

Radial distribution function of methanol

Na+ Diluted methanolic NaCl solution (T = 298 K, p = 1 bar)

4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse

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SLIDE 16

Laboratory of Engineering Thermodynamics

  • Prof. Dr.-Ing. H. Hasse

 New atomistic force fields for ions

 Alkali-cations: Li+, Na+, K+, Rb+, Cs+  Halide-anions: F-, Cl-, Br-, I-

 Model adjustment in aqueous systems

 Reduced density  Self-diffusion coefficient and RDF

 Predictions

 Electric conductivity  Temperature dependence of the reduced density  Reduced density of methanolic solutions

Summary

16 4th November 13 Martin Horsch, Steffen Reiser, Stephan Deublein, Jadran Vrabec, and Hans Hasse