Question 2 (40 marks) A purification system with recycle is used to recover the solvent DMF from a waste gas containing 55%-mole DMF (the remaining is air). The product is only to have 10%-mole of DMF (see Figure 1). The purification unit can only remove two third of the DMF in the combined feed to the unit. For 100 mol/s of fresh feed, calculate the recycle rate (mol/s) and rate of DMF removal (mol/s). F6 F1 F2 F3 Flow splitter F5 DMF 55% Air Purification unit DMF Air 90% F4 DMF Figure 1. DMF removal system