List of top Mass Transfer Questions on Absorption

Gas containing 0.8 mol% component \(A\) is to be scrubbed with pure water in a packed bed column to reduce the concentration of \(A\) to 0.1 mol% in the exit gas. The inlet gas and water flow rates are 0.1 kmol/s and 3.0 kmol/s, respectively. For the dilute system, both the operating and equilibrium curves are considered linear. If the slope of the equilibrium line is 24, the number of transfer units, based on the gas side, \(N_{OG}\) is __________ (rounded off to 1 decimal place).

Gas containing 0.8 mol% component \(A\) is to be scrubbed with pure water in a packed bed column to reduce the concentration of \(A\) to 0.1 mol% in the exit gas. The inlet gas and water flow rates are 0.1 kmol/s and 3.0 kmol/s, respectively. For the dilute system, both the operating and equilibrium curves are considered linear. If the slope of the equilibrium line is 24, the number of transfer units, based on the gas side, \(N_{OG}\) is __________ (rounded off to 1 decimal place).

A gas stream containing 95 mol% CO₂ and 5 mol% ethanol is to be scrubbed with pure water in a counter-current, isothermal absorption column to remove ethanol. The desired composition of ethanol in the exit gas stream is 0.5 mol%. The equilibrium mole fraction of ethanol in the gas phase, \( y^* \), is related to that in the liquid phase, \( x \), as \( y^* = 2x \). Assume CO₂ is insoluble in water and neglect evaporation of water. If the water flow rate is twice the minimum, the mole fraction of ethanol in the spent water is:
Wet air containing 10 mole percent water vapor is dried by continuously passing it through a column of CaCl\(_2\) pellets. The pellets remove 50 percent of water from wet air entering the column. The mole percent of water vapor in the product stream exiting the column is ____________________ (rounded off to two decimal places).