Diffusion behavior in a liquid-liquid interfacial crystallization by molecular dynamics simulations

Abstract

Interfacial crystallization, such as surface crystallization in solution (solid-liquid) and liquid-liquid crystallization, gives us an asymmetric reaction field and is a technique for morphology control of crystals. In the liquid-liquid crystallization, the concentration distribution of solute ions and solvent molecules at the liquid-liquid interface directly relates to nucleation, crystal growth, and crystal morphology. Nonequilibrium molecular dynamics (MD) simulations have been performed at interfaces in NaCl solution/1-butanol and KCl solution/1-butanol system in order to clarify diffusion behavior of solute ions and solvent molecules. As simulation results, the hydrated solute ions were dehydrated with the diffusion of water from solution phase into 1-butanol phase. The different dehydration behaviors between NaCl and KCl solution can be also obtained from MD simulation results. Aggregated ions or clusters were formed by the dehydration near the solution/1-butanol interface. By comparison on the normalized number of total solute ions, the size and number of generated cluster in KCl solution/1-butanol interface are larger than those in the NaCl system. This originates in the difference hydration structures in the each solute ion.

Particle Preparation and Morphology Control with Mutual Diffusion Across Liquid-Liquid Interfaces

“…The difference in surface morphology derives from the mutual diffusion behavior following the organic solvent. Phase diagrams of water/1-butanol and /2butanone were previously reported (Kitayama et al, 2009b;Kadota et al, 2013;Deki et al, 2016). In the solubility of 1-butanol in water, the amount of water diffusing into 1-butanol was much greater than that of 1-butanol diffusing into water at 25 °C.…”

Mutual diffusion diagram of liquid-liquid interfaces for morphological control of NaCl crystals

“…When 2-butanone was used, the geometric standard deviation was b 1.60 even for a contact time of 1200 s. Monodisperse crystals were obtained compared with other organic solvents. In our previous study, we used a molecular dynamics (MD) simulation to show that the difference in the interaction between solute and organic solvent caused the difference in geometric standard deviation [35,36]. The amount of precipitation increased in the order 2-butanone N 2-butanol N 2-methyl-1-propanol N 1-butanol (Fig.…”

One-dimensional magnetism in a facile spin 1/2 Heisenberg antiferromagnet with a low saturation field

“…The present study involves the growth of single crystals of CuD using the liquid/liquid diffusion technique which involves the slow diffusion of one solution into another. 34,35 In this technique, two solutions are added in a container, such that they form distinct layers. This is possible when the two solutions have different densities.…”

“…With the passage of time, as more and more solution B diffuses into solution A, the solubility of the mixture at the interface decreases more and more for the target compound until the oversaturated solute is forced to precipitate at the liquid-liquid boundary where crystals form. 34,35 The type of solvent used for making the two solutions determines the structure and morphology of the obtained crystals.…”