Abstract
The selective extraction of sulfate and chloride ions from mixed solvent solutions was investigated. The mixed solvents consisted of water and 50 to 100%-w (salt-free solvent) ethylene glycol. The extraction was measured for mixed solvent solutions containing only sulfate and chloride, and mixed solvent solutions saturated with trona (sodium sesquicarbonate, Na
2
CO
3
· NaHCO
3
· 2H
2
O(s). Three anion exchange resins, Dowex 1X8-50, Dowex 21K-Cl, and Dowex MSA-1, were investigated for their chemical and physical resistance to the mixed solvent carbonate/bicarbonate solutions, for their swelling behavior in the different mixed solvents, and for their extraction efficiency for chloride and sulfate.
The loading of the ion exchangers was fitted to a Langmuir-type sorption model. While the extraction from trona-free mixed solvents was well reproduced, the loading of the ion exchangers with chloride and sulfate from trona-saturated mixed solvent solutions did not fit the sorption model. It appears, rather, that under these conditions chloride and sulfate are "salted out" of the bulk solution and driven into the ion exchangers.