Question

Coffee is decaffeinated industrially using supercritical (sc) CO2. One advantage to using scCO2 is that the polarity of the supercritical fluid can be tuned by varying temperature, pressure and cosolvent additives. However, the need for high temperatures and pressures makes generation of scCO2 impractical in a teaching lab setting. Based on its structure and polarity, would you expect caffeine to be soluble in liquid CO2 (i.e. if we carried out this experiment with tea leaves instead of orange rind, would you expect it to work)? Why/why not?

Answer 1

Answer:

Yes

Explanation:

A supercritical fluid has good properties for both liquid and as for extraction properties, the advantages then include:

• The fact that it has a lower viscosity than liquid CO2 allowing it to move through and around coffee beans more thoroughly with creating back pressure
• Its density is comparable to that of liquid CO2 meaning there is much CO2 per litre as there is liquid form making it more efficient
• It has a higher diffusivity than liquid CO2 which aids with penetration of the coffee beans on a molecular level

This experiment would not work with tea leaves because they also contain caffeine