TY - JOUR
T1 - Formation of porous crystals by coupling of dissolution and nucleation process in fractional crystallization
AU - Liu, Chang
AU - Ji, Yuanhui
AU - Bai, Yang
AU - Cheng, Fangqin
AU - Lu, Xiaohua
PY - 2007/12/1
Y1 - 2007/12/1
N2 - The fractional crystallization of carnallite (KMgCl3·6H2O) in pure water, KCl aqueous solution and MgCl2 aqueous solution was studied. When carnallite was dissolved in pure water, porous crystals of KCl were formed. However, when the fractional crystallization in KCl or MgCl2 aqueous solution occured, the solid crystals of KCl with different morphologies were formed. A theoretical model was established to explore this phenomenon. The ionic product of carnallite and KCl with distance far from the surface of carnallite was analyzed in which the activity coefficient of KCl, MgCl2 and water were calculated with Lu-Maurer model. The dissolution of carnallite, the diffusion of KCl and MgCl2 in bulk solutions and the nucleation as well as crystal growth of KCl were investigated in detail. It was concluded that the coupling of the high dissolution rate of carnallite and the high nucleation rate of KCl nearby the surface of carnallite resulted in the porous crystals of KCl. TG and SEM analysis shows that high water content in KCl crystals prepared by fractional crystallization of carnallite in water results from the surface porous structure of crystals.
AB - The fractional crystallization of carnallite (KMgCl3·6H2O) in pure water, KCl aqueous solution and MgCl2 aqueous solution was studied. When carnallite was dissolved in pure water, porous crystals of KCl were formed. However, when the fractional crystallization in KCl or MgCl2 aqueous solution occured, the solid crystals of KCl with different morphologies were formed. A theoretical model was established to explore this phenomenon. The ionic product of carnallite and KCl with distance far from the surface of carnallite was analyzed in which the activity coefficient of KCl, MgCl2 and water were calculated with Lu-Maurer model. The dissolution of carnallite, the diffusion of KCl and MgCl2 in bulk solutions and the nucleation as well as crystal growth of KCl were investigated in detail. It was concluded that the coupling of the high dissolution rate of carnallite and the high nucleation rate of KCl nearby the surface of carnallite resulted in the porous crystals of KCl. TG and SEM analysis shows that high water content in KCl crystals prepared by fractional crystallization of carnallite in water results from the surface porous structure of crystals.
KW - Dissolution
KW - Fractional crystallization
KW - Ionic product
KW - Nucleation
UR - http://www.scopus.com/inward/record.url?scp=35348912434&partnerID=8YFLogxK
UR - https://www.sciencedirect.com/science/article/pii/S0378381207004463?via%3Dihub
U2 - 10.1016/j.fluid.2007.07.052
DO - 10.1016/j.fluid.2007.07.052
M3 - Article
AN - SCOPUS:35348912434
SN - 0378-3812
VL - 261
SP - 300
EP - 305
JO - Fluid Phase Equilibria
JF - Fluid Phase Equilibria
IS - 1-2
ER -