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Poisson's effects in electrical field flow fractionation
Joseph J Biernacki1, P Manikya Mellacheruvu, Satish M Mahajan
1Department of Electrical and Computer Engineering, Tennessee Technological University, Cookeville, TN 38505, USA. jbiernacki@tntech.edu
Journal of Separation Science
|July 11, 2008
Summary
Electrical Field Flow Fractionation (ELFFF) models using Poisson's equation reveal nonlinear field behavior. This study identifies conditions where traditional Laplace models fail, impacting ELFFF device performance.
Area of Science:
- Electrokinetic phenomena
- Separation science
- Computational fluid dynamics
Background:
- Traditional Electrical Field Flow Fractionation (ELFFF) models assume Laplace's equation for electric fields.
- This assumption holds for dilute systems but fails when double-layer effects reduce effective potentials.
- Reduced effective potentials can lead to nonlinear field distributions and high local analyte concentrations.
Purpose of the Study:
- To investigate the validity of Laplace's equation in ELFFF under non-ideal conditions.
- To explore the necessity of Poisson's equation for modeling ELFFF.
- To analyze the impact of concentration and effective field strength on ELFFF performance.
Main Methods:
- Developed and implemented a steady-state ELFFF simulation model based on Poisson's equation.
- Identified the operational domain where Laplace's equation remains valid.
- Simulated ELFFF performance under varying analyte concentrations and effective field strengths.
Main Results:
- Demonstrated that Poisson's equation is required when effective potentials are significantly lower than applied potentials due to double-layer effects.
- Characterized the transition from linear (Laplace) to nonlinear (Poisson) electric field behavior.
- Quantified the influence of concentration and field strength on ELFFF separation.
Conclusions:
- ELFFF modeling requires Poisson's equation for accurate predictions in systems with significant double-layer formation.
- Understanding the nonlinear field distribution is crucial for optimizing ELFFF device design and performance.
- The study provides a framework for predicting ELFFF behavior across different operating regimes.
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