Abstract
The antisolvent crystallization experiment was carried out batchwisely to study the crystallization phenomena of sodium chloride under the influence of potassium chloride impurities. To observe crystallization phenomena, supersaturation was produced by the addition of ethanol into the saturated solution of high ethanol concentration. The sodium chloride crystals obtained were found to be monodispersed under some operational conditions. It was suggested that monodispersed crystals were obtained when the supersaturation was controlled in an adequate range. Obtained crystals had smooth surfaces in the case of NaCl/KCl=6 and 10, but had hollowed surfaces in the case of NaCl/KCl=14 in the starting solution. The difference in crystal surface condition was considered to be influenced by the existence of potassium ion as impurities. The potassium content was increased when the potassium concentration was high in the starting solution. The induction period seemed to decrease when the potassium concentration was high in the starting solution. The average crystal size tended to decrease when the potassium concentration was high in the starting solution. These facts were considered in light of the phenomena, in which nucleation was accelerated by the existence of potassium ion and the average crystal size decreased with an increase in number of produced crystals.
