3 replies to this topic

[curious_cat]

I'm having a hard time finding a data-source for acetaldehyde solubility in MEK (Methyl Ethyl Ketone). Anyone know? Any places I should look up?

 

Even an estimate will do. The pressure is 1 atm(abs) and Temp. is ~60 C.

 

[fseipel]

You can go to NIST webbook & look up the Antoine coefficients for acetaldehyde & for MEK or use the plot feature to find the pure component vapor pressures (VP) at 60 deg C.  Reading off plot, we have 273+60 = 333 K, 3.6 Bar VP for acetaldehyde (click + hold on plot to zoom in), and VP MEK = 0.515 bar.  Atm pressure = 1.01325 bar (call it 1 Bar).  So then you just solve the equation VP = Xa * VPa + (1-Xa)*VPMEK = 1 Bar, solving for X sub a, where Xa = mole fraction acetaldehyde & VPa = Vapor Pressure of Pure Acetaldehyde @ 60 deg C and VPMEK = vapor pressure of pure MEK at 60 deg C.  You'll come up with mole fraction of 0.163 Acetaldehyde & 0.837 MEK.  ChemCAD gives 0.166 & I wouldn't expect much deviation from non-ideality.  This is typically described as the 'equilibrium' concentration instead of 'solubility'.  The term solubility is typically used in describing aqueous streams or two phase mixtures, e.g. how much of a solid organic can dissolve in a liquid or how much salt water can hold at a given temperature.  When you have more than two components I tend to prefer to use the simulators if available to you.

[curious_cat]

You can go to NIST webbook & look up the Antoine coefficients for acetaldehyde & for MEK or use the plot feature to find the pure component vapor pressures (VP) at 60 deg C.  Reading off plot, we have 273+60 = 333 K, 3.6 Bar VP for acetaldehyde (click + hold on plot to zoom in), and VP MEK = 0.515 bar.  Atm pressure = 1.01325 bar (call it 1 Bar).  So then you just solve the equation VP = Xa * VPa + (1-Xa)*VPMEK = 1 Bar, solving for X sub a, where Xa = mole fraction acetaldehyde & VPa = Vapor Pressure of Pure Acetaldehyde @ 60 deg C and VPMEK = vapor pressure of pure MEK at 60 deg C.  You'll come up with mole fraction of 0.163 Acetaldehyde & 0.837 MEK.  ChemCAD gives 0.166 & I wouldn't expect much deviation from non-ideality.  This is typically described as the 'equilibrium' concentration instead of 'solubility'.  The term solubility is typically used in describing aqueous streams or two phase mixtures, e.g. how much of a solid organic can dissolve in a liquid or how much salt water can hold at a given temperature.  When you have more than two components I tend to prefer to use the simulators if available to you.

 

Thanks a lot. Somehow this approach escaped me.

 

I was lost looking for solubility as something distinct from essentially a VLE calculation. Makes perfect sense. 

[curious_cat]

Out of curiosity: Was there a reason you seemed confident non-ideality won't be an issue here?

 

The pressure being low fugacity is no worry. But what about non-unity activity coefficients?