Extractive Separation of Scandium from Strongly Alkaline Solution by Quaternary Ammonium Salt

ABSTRACT

Extraction and separation of scandium(III) from concentrated sodium hydroxide solution using quaternary ammonium salt (Aliquat 336, CH₃R₃NOH) in kerosene as a diluent with 10% (v/v) octanol as a modifier were investigated. The parameters that affect the extraction process were separately studied. On the basis of the slope analysis method, the composition of the extracted species was proposed to be [CH₃R₃NSc(OH)₄]. The structure of the extracted metal species was supported by FT-IR investigations. Furthermore, the thermodynamic parameters related to the extraction process were estimated and the extraction process was found to be exothermic and spontaneous. The loading capacity of Aliquat 336 towards Sc(III) and stripping of loaded Sc(III) from the organic phase were also examined. Based on the acquired results, the method developed was applied for the recovery and separation of Sc(III) and other metal ions from a synthetic solution similar in composition to that expected from the leaching solution of red mud in strongly alkaline medium.

KEYWORDS:

• Extraction
• scandium(III)
• Aliquat 336
• alkaline leaching
• red mud