An aqueous waste stream containing 1.0 mole% of hydrogen sulfide (H₂S) dissolved in water will be treated by stripping the liquid with air in a counter current packed tower at 20°C and 12.50 atm total system pressure. The total flow rate of this liquid feed stream is 100 lbmole/h. Compressed air at 12.5 atm containing no H₂S is also introduced into the tower. At 20°C, the Henry’s law constant for the H₂S-water system is H = 515 atm. It is desired to remove 80% of H₂S from the liquid.
a. What is the minimum air flow rate into the tower, AG_s,min?
b. What is the maximum possible mole fraction of H₂S in the outlet gas stream as the minimum air flow rate?