Inverse Gas Chromatography (IGC)

Inverse Gas Chromatography (IGC) Motivation

Examples

• Inverse Gas Chromatography (IGC): the stationary phase (e.g., polymers, polymer blends ionic liquids etc.) is of interest, unlike the traditional GC method

• Separation factor to characterise entrainers for separation of substances using extractive distillation

• Applications: activity coefficients of volatiles at infinite dilution / gas solubility in high-boiling/low volatile liquids

α1,2 

γ1 P01LV γ2 P02LV

• Fast method with a reasonable accuracy • Key value: retention time

• Selectivity of an extractive agent to separate substances using liquid-liquid extraction

Experimental setup S1,2 

• House-built gas chromatograph

γ1 γ2

• Thermal conductivity detector • Henry constants to characterise suitable solvents for absorption

• Complete data evaluation with PC

H12  γ1 P01LV  01LV

oven oven

• Flory-Huggins interaction parameter to find a suitable solvent for a polymer

χ12  ln γ1  1 • Temperature dependence of limiting activity coefficients 1. Carrier gas flow 2. Detector 3. Injection block

4. Column 5. Water saturator 6. Flowmeter

-1 -1.2 -1.4 ?

ln(gamma )

Experimental procedure / data reduction • Preparation of the column with a known amount of a stationary phase of interest • Measurement of inlet and outlet pressure, oven temperature, flow rate at ambient conditions, retention time of volatile probes • Calculation of the net retention volume corrected to the column temperature and pressure

P v G  t1  t0  V ( Pamb , Tamb )  J 32  amb Pout J 32 

 P (Tamb )  T    1  Pamb   Tamb LV water

2 3  Pin Pout   1   is the James-Martin Factor (pressure correction) 2  Pin Pout 3  1 

-1.6 -1.8 -2 -2.2 -2.4 -2.6 -2.8 -3 0.0015

0.0017

 

ln 

 n  R  T  ( Bii  v0Li ) LV    ln G 3 LV  P0i (T ) R T  v  Pi (T ) 

Contact: [email protected]

0.0021

1/T/ [K-1] (1/T) (1/K)

 Plotting ln

   as a function of 1/T results a straight line  i

 Slope of the line corresponds with the partial molar excess enthalpy of the monomer at infinite dilution in the polymer

• Calculation of limiting activity coefficients  i

0.0019

  ln(  )  h E ,   i i  ( 1 )  R T  

0.0023