Question

An aqueous solution containing 5% acid is subjected to counter – current extraction using ether as solvent. The ether extract is found to contain 15% acid and 5% H2O. The extracted water layer contains negligible acid but has 3% ether. For every 600 lbs of acid extracted, calculate the weights of all streams in the process.

Answer 1

The flow diagram

Mass of acid extracted = 600 lb

Mass of ether extract layer

m3 = 600/0.15 = 4000 lb

Mass of H2O in ether extract layer = 4000*0.05 = 200 lb

Mass of ether in ether extract layer = 4000*0.80 = 3200 lb

m1 = mass of acid / 0.05 = 600/0.05 = 12000 lb

Mass of H2O in m1 = 12000*0.95 = 11400 lb

Water balance

Water in m1 + water in m2 = water in m3 + water in m4

11400 + 0 = 200 + water in m4

Water in m4 stream = 11200 lb

m4 = 11200/0.97 = 11547 lb

Mass of ether in m4 = 11547 - 11200 = 347 lb

Total mass balance

m1 + m2 = m3 + m4

12000 + m2 = 4000 + 11547

m2 = 3547 lb