A battery of cylindrical membranes is used for an extractive bioconversion (fermentation and extraction of product occur at the same time). A 20% glucose in water solution is passed through the annular space at a rate of 50 kg/h. An organic solvent enters the inner tube at a rate of 40 kg/h as well.
Once immobilised in the membrane, the yeast cells cannot reproduce but convert glucose to ethanol according to the equation:
C6H12O6 → 2C2H6O + 2CO2
Ethanol is soluble in the solvent; it diffuses into the inner tube and is carried out of the system. CO2 gas exits from the membrane unit through an escape valve. In the aqueous stream leaving the annular space, the concentration of unconverted glucose is 0.5% and the concentration of ethanol is 0.5%. If the system operates at steady state.
(a) What is the concentration of ethanol in the solvent stream leaving the reactor?
(b) What is the mass flow rate of CO2?