Lanthanum and Cerium Separation Using an Aqueous Two-Phase System with Ionic Liquid

In this work, an organic solvent-free extraction approach was developed to selectively separate La from Ce using an ionic liquid-based aqueous two-phase system (ILATPS). ILATPSs composed of 1-ethyl-3-methylimidazolium chloride, C2MIMCl, K2CO3 (or K2HPO4), and water at 283, 298, and 313 K were obtained. The biphasic region decreased slightly with increasing temperature. These ILATPSs were applied for the separation of lanthanum from cerium. Some parameters that affect the separation of La and Ce, such as the alkyl chain length of the imidazolium cation, the type of electrolyte, and extractant concentration, were investigated. The best conditions for separation were achieved using the ILATPS formed by C2MIMCl + K2CO3 + H2O and 40.4 mmol kg–1 alizarin red S (as an extractant). The extraction percentage for La was 100%, whereas the extraction for Ce was 5.4%, yielding a separation factor between La and Ce equal to 2620.