Experimental and kinetic modeling study of multistage freezing-melting process and salt rejection of seawater

Abstract

Multistage freezing-melting process using successive indirect freezing-melting cycles of seawater samples was investigated to obtain potable water. The salinity of seawater samples experiences a reducing geometric progressive change with the freezing-melting cycles. The salinity of each stage term decreases by a constant factor of ≈ 0.61. The higher coefficient of determination R2 value of the geometric progressive model suggests that this model can be used to explain the experimental data and predict the salinity of the produced frozen water at different initial salt concentrations and different stages. A gradual melting/sweating of frozen water layers under the effect of a temperature gradient was studied to achieve a better understanding of salt rejection and the mechanism of salts formation inside the crystallized region. It is found that the salt distribution in a concentration gradient flowing from cold to hot outside of the ice surface associated with the temperature gradient in salt ice is exponential inversely proportional to the distance axis of the ice phase.