Salting-Out Effect of Dipotassium Hydrogen Phosphate on the Recovery of Acetone, Butanol, and Ethanol from a Prefractionator

Dipotassium hydrogen phosphate (K 2 HPO 4 ) has been investigated as an excellent salting-out agent to recover (acetone + butanol + ethanol) (ABE) from a prefractionator. The increasing additions of K 2 HPO 4 ·3H 2 O to the ABE system under unsaturated conditons show strong salting-out effects on the ABE. This favorable salting-out effect is based on the hydration of the charged ions. The HPO 4 2– ions may destroy the “hydration shell”, but the crescent concentrations of K 2 HPO 4 make positive salting-out effects on the ABE. More acetone, 1-butanol, and ethanol are recovered after higher-level concentrations of K 2 HPO 4 solution are added to the ABE system. Meanwhile, the equilibrium time shortens. A higher temperature can also make the equilibrium time shorter. The smallest amount of K 2 HPO 4 in the organic phase causes no trouble for the (salting-out + distillation) process in an industrial application.