Morphology of Particles Precipitated by Liquid-liquid Interfacial Crystallization and Mutual Diffusion of NaCl Aqueous Solution and Organic Liquid at the Interface

Abstract

Liquid-Liquid interfacial crystallization has been carried out in NaCl aqueous solution/1-butanol and/2-butanone systems. The crystallization at the interface between NaCl aqueous solution and organic liquid was proceeded by the supersaturation caused from the mutual diffusion of the aqueous solution and the organic liquid. The NaCl crystalline particles precipitated at the interface showed a bimodal size distribution by using a supersaturated aqueous solution. However, the precipitation in an unsaturated aqueous solution can produce NaCl crystals with unimodal size distribution.
The precipitated NaCl crystals were asymmetric in shape. The asymmetry was derived from the dynamics of the aqueous solution, the organic liquid and self-weight of the particles. Consequently, the transport of the solution into the organic liquid was confirmed by measuring the electric resistance in the organic liquid phase as a function of the contact time. Furthermore, the precipitation mass and rate of NaCl particles measured for two types of organic liquids showed that the precipitation properties depend on types of organic liquids.