Drowning-out crystallization of sodium molybdate in aqueous-ethanol solutions

Abstract

The drowning-out crystallization process of sodium molybdate (Na2MoO4) was studied in water-ethanol solutions at room temperature. Sodium molybdate was separated from the solution in well-crystalline particles using less water and energy compared with the industrial processes that use evaporative crystallization. Results showed that crystallization of sodium molybdate di-hydrate was achieved after 20 or 40 min in one or two operating stages for super-saturation control with the addition of 25 or 50 vol.% ethanol, respectively. Crystallization with ethanol could reduce the operating costs for about 32% with respect to the conventional evaporative crystallization method, and the exhausted ethanol in the aqueous solution could be recovered by distillation and then recycled into the process.

Keywords

• crystallization
• drowning-out
• ethanol
• molybdenum
• sodium-molybdate