Binary chromatographic retention times from perturbations in flowrate and composition

M.J. Heslop, B.A. Buffham, G. Mason

Research output: Contribution to journalArticle

Abstract

This work is a theoretical and experimental investigation of the binary retention time (t step) when the disturbance is made to a chromatographic system by adding a small flow of one of the pure components. The established theory is for addition of a pulse: in this case, the retention time (t pulse) depends on the two binary isotherm gradients, and should be independent of the choice of pulse gas. From the column material balance, the value of t step also depends on the column pressure drop and perturbation gas-the value of t step should always be greater for the more-adsorbed component. The theory has been validated from results on the nitrogen-argon-5A zeolite system at 25, 54 and 81 °C. For a 50% mixture at 25 °C with a column pressure drop of 0.1 bar, the values of t step are 257 and 254 seconds for the nitrogen and argon perturbations. The values of t step are different because addition of the perturbation flow causes a very small increase in average column pressure (about 0.5 mbar), which causes the binary isotherm gradients to be measured in (slightly) different directions along the isotherm surface. The intention is to determine the value of t step for the case of a zero change in the average column pressure: experimentally, this would require a column with a zero pressure drop. The material balance shows that t step for a column with a zero pressure drop is obtained from a simple weighted function of the values of t step for the two pure-component perturbations. Accurate determination is essential because the 'zero pressure drop' values are used to determine binary adsorption isotherms which are, of course, at a fixed pressure.
LanguageEnglish
Pages143-155
Number of pages13
JournalAdsorption
Volume14
Issue number1
DOIs
Publication statusPublished - Feb 2008

Fingerprint

Pressure drop
pressure drop
perturbation
Isotherms
Chemical analysis
Argon
isotherms
material balance
Nitrogen
Gases
Zeolites
Adsorption isotherms
pulses
argon
nitrogen
gradients
causes
gases
disturbances
adsorption

Keywords

  • binary adsorption
  • retention time
  • 5A zeolite
  • column pressure drop

Cite this

Heslop, M.J. ; Buffham, B.A. ; Mason, G. / Binary chromatographic retention times from perturbations in flowrate and composition. In: Adsorption. 2008 ; Vol. 14, No. 1. pp. 143-155.
@article{d2ddee5cf01942ba915bf496e3172770,
title = "Binary chromatographic retention times from perturbations in flowrate and composition",
abstract = "This work is a theoretical and experimental investigation of the binary retention time (t step) when the disturbance is made to a chromatographic system by adding a small flow of one of the pure components. The established theory is for addition of a pulse: in this case, the retention time (t pulse) depends on the two binary isotherm gradients, and should be independent of the choice of pulse gas. From the column material balance, the value of t step also depends on the column pressure drop and perturbation gas-the value of t step should always be greater for the more-adsorbed component. The theory has been validated from results on the nitrogen-argon-5A zeolite system at 25, 54 and 81 °C. For a 50{\%} mixture at 25 °C with a column pressure drop of 0.1 bar, the values of t step are 257 and 254 seconds for the nitrogen and argon perturbations. The values of t step are different because addition of the perturbation flow causes a very small increase in average column pressure (about 0.5 mbar), which causes the binary isotherm gradients to be measured in (slightly) different directions along the isotherm surface. The intention is to determine the value of t step for the case of a zero change in the average column pressure: experimentally, this would require a column with a zero pressure drop. The material balance shows that t step for a column with a zero pressure drop is obtained from a simple weighted function of the values of t step for the two pure-component perturbations. Accurate determination is essential because the 'zero pressure drop' values are used to determine binary adsorption isotherms which are, of course, at a fixed pressure.",
keywords = "binary adsorption, retention time, 5A zeolite, column pressure drop",
author = "M.J. Heslop and B.A. Buffham and G. Mason",
year = "2008",
month = "2",
doi = "10.1007/s10450-007-9082-9",
language = "English",
volume = "14",
pages = "143--155",
journal = "Adsorption",
issn = "0929-5607",
number = "1",

}

Binary chromatographic retention times from perturbations in flowrate and composition. / Heslop, M.J.; Buffham, B.A.; Mason, G.

In: Adsorption, Vol. 14, No. 1, 02.2008, p. 143-155.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Binary chromatographic retention times from perturbations in flowrate and composition

AU - Heslop, M.J.

AU - Buffham, B.A.

AU - Mason, G.

PY - 2008/2

Y1 - 2008/2

N2 - This work is a theoretical and experimental investigation of the binary retention time (t step) when the disturbance is made to a chromatographic system by adding a small flow of one of the pure components. The established theory is for addition of a pulse: in this case, the retention time (t pulse) depends on the two binary isotherm gradients, and should be independent of the choice of pulse gas. From the column material balance, the value of t step also depends on the column pressure drop and perturbation gas-the value of t step should always be greater for the more-adsorbed component. The theory has been validated from results on the nitrogen-argon-5A zeolite system at 25, 54 and 81 °C. For a 50% mixture at 25 °C with a column pressure drop of 0.1 bar, the values of t step are 257 and 254 seconds for the nitrogen and argon perturbations. The values of t step are different because addition of the perturbation flow causes a very small increase in average column pressure (about 0.5 mbar), which causes the binary isotherm gradients to be measured in (slightly) different directions along the isotherm surface. The intention is to determine the value of t step for the case of a zero change in the average column pressure: experimentally, this would require a column with a zero pressure drop. The material balance shows that t step for a column with a zero pressure drop is obtained from a simple weighted function of the values of t step for the two pure-component perturbations. Accurate determination is essential because the 'zero pressure drop' values are used to determine binary adsorption isotherms which are, of course, at a fixed pressure.

AB - This work is a theoretical and experimental investigation of the binary retention time (t step) when the disturbance is made to a chromatographic system by adding a small flow of one of the pure components. The established theory is for addition of a pulse: in this case, the retention time (t pulse) depends on the two binary isotherm gradients, and should be independent of the choice of pulse gas. From the column material balance, the value of t step also depends on the column pressure drop and perturbation gas-the value of t step should always be greater for the more-adsorbed component. The theory has been validated from results on the nitrogen-argon-5A zeolite system at 25, 54 and 81 °C. For a 50% mixture at 25 °C with a column pressure drop of 0.1 bar, the values of t step are 257 and 254 seconds for the nitrogen and argon perturbations. The values of t step are different because addition of the perturbation flow causes a very small increase in average column pressure (about 0.5 mbar), which causes the binary isotherm gradients to be measured in (slightly) different directions along the isotherm surface. The intention is to determine the value of t step for the case of a zero change in the average column pressure: experimentally, this would require a column with a zero pressure drop. The material balance shows that t step for a column with a zero pressure drop is obtained from a simple weighted function of the values of t step for the two pure-component perturbations. Accurate determination is essential because the 'zero pressure drop' values are used to determine binary adsorption isotherms which are, of course, at a fixed pressure.

KW - binary adsorption

KW - retention time

KW - 5A zeolite

KW - column pressure drop

U2 - 10.1007/s10450-007-9082-9

DO - 10.1007/s10450-007-9082-9

M3 - Article

VL - 14

SP - 143

EP - 155

JO - Adsorption

T2 - Adsorption

JF - Adsorption

SN - 0929-5607

IS - 1

ER -