Separation of GaCl₃ from AlCl₃ by Solid-Liquid Extraction and Stripping Using Anhydrous n-Dodecane and NaCl

Separation of GaCl₃ from other associating chloride compounds (e.g. AlCl₃, SbCl₃, and InCl₃) is generally achieved by hydrometallurgical processes. In this study, we explore the separation of GaCl₃ from these compounds on the basis of the exceptionally high solubility of GaCl₃ in hydrocarbon solvents. We found that GaCl₃ can be efficiently extracted by anhydrous n-dodecane from a solid mixture of GaCl₃ and AlCl₃; on the contrary, SbCl₃ and InCl₃ significantly reduce the extraction of GaCl₃. On the basis of Lewis acidity theory and study of the Raman spectra, it is shown that formation of the ionic compound [SbCl₂][GaCl₄] is responsible for the reduced GaCl₃ extraction. Formation of [InCl₂][GaCl₄] is also likely, but further study is needed to support the existence of this compound. Further making use of the strong Lewis acidity of GaCl₃, GaCl₃ can be efficiently stripped from the loaded n-dodecane phase by solid NaCl through formation of NaGaCl₄. The extraction of GaCl₃ by n-dodecane, in combination with its stripping by NaCl, is a solvometallurgical process that is essentially different from the hydrometallurgical processes for the separation of GaCl₃ and AlCl₃.