The present work deals with ultrasound assisted crystallisation of lactose from lactose solution. The crystallisation of lactose was completed rapidly by applying the ultrasound waves in the presence of an anti-solvent (n-propanol), at the room temperature (30±3°C). The yield of lactose was found to be more than 85% (w/w) in 4 minutes of sonication. The spread of the crystal size distribution was found to decrease with increase in sonication time.

Numerical values of the NRTL equation parameters for calculation of the vapour - liquid - liquid equilibria (VLLE) at atmospheric pressures have been presented for 5 ternary mixtures. These values were fitted to the experimental VLLE and vapour - liquid equilibrium (VLE) data to describe simultaneously, as accurately as possible, the VLE and the liquid - liquid equilibria (LLE). The coefficients of this model called further NRTL-VLL were used for simulations of n-propanol dehydration via heterogeneous azeotropic distillation. The calculations performed by a ChemCAD simulator were done for 4 mixtures using hydrocarbons, ether and ester as an entrainer. In majority simulations the top streams of the azeotropic column had composition and temperature similar to the corresponding experimental values of ternary azeotropes. The agreement between the concentrations of both liquid phases formed in a decanter and the experimental values of the LLE was good for all four simulations. The energy requirements were the most advantageous for the simulation with di-npropyl ether (DNPE) and isooctane. Simulations were performed also for one mixture using the NRTL equation coefficients taken from the ChemCAD database. In that case the compositions of the liquid organic phases leaving the decanter differed significantly from the experimental LLE data.