Formation of fine crystals of potassium chloride dissolved in aqueous ethanol solution by spray evaporation

Spray evaporation of aqueous ethanol solution with dilute potassium chloride (KCl) was examined for the generation of extremely small electrolyte crystals in dry state. Ethanol content in the aqueous solution played an important role in decreasing the solubility of KCl. Evaporation of small liquid droplets of the aqueous ethanol solution produced a small amount of KCl crystals. The concentration of ethanol in the solution was the operative variable, and the ultrasonic spray nozzle and flow rate of the solution were fixed in this study. The crystals collected were observed by SEM, and crystal size distributions were obtained for different operative conditions. The average crystal size ranged from 100 to 800 nm. When the ethanol content increased in the solution, the crystal size decreased. We consider the crystal size according to the slight solubility of KCl in liquid droplets of aqueous ethanol solution.