Eutectic freeze crystallization using CO₂ clathrates

Highly soluble salts can be separated from aqueous solutions by eutectic freeze crystallization (EFC). This technique delivers significant energy savings in comparison with evaporative crystallization. The eutectic temperature can be raised by crystallizing CO₂ clathrates instead of normal ice. Application of this process is especially efficient for salt solutions with eutectic points at low temperatures, such as CaCl₂ (-55°C). In this work the shift of the eutectic point is predicted by use of a model for NaCl and CaCl₂ solutions. Experiments are executed under eutectic conditions, with these substances proving the feasibility of the eutectic clathrate freezing process. Energy calculations show that by using eutectic clathrate crystallization instead of regular EFC the electric energy consumption ran be reduced by 32%.