Synthesis of ionic liquid for the separation of rare earth elements and investigation of the usability of improved ionogels

In the study, a malonamide functionalized ionic liquid ([MAL][NTf2]) was synthesized. The synthesis of ionic liquid was carried out in four steps and the structure was evaluated by NMR, FTIR and HRMS analyzes. In the first part of the study, solvent extractions of Nd, Dy, Eu, La, Lu, Y and Yb rare earth elements, Ba, Mg, Al, Fe, Ni and Co metals, green, blue and red phosphors and Nd / Dy and Eu/Zn mixture were carried out using the synthesized ionic liquid in an acidic medium. The extraction studies were followed depending on pH. The metal concentrations were determined by ICP analysis. Then, in order to give a solid form to the synthesized ionic liquid; the ionogel was synthesized with a silica source (TMOS, TEOS, MTMS) and formic acid used as both a solvent and a catalyst. System parameters such as silica source type, molar ratios of components, gelling time and aging time were investigated for ionogel formation. Ionogels were characterized by BET, SEM, TEM, FTIR, Raman, TGA, XRD, UV-Vis, CHN-S analyses and hardness test. The obtained ionogels were tested for their applicability as a membrane in the separation of industrially important Eu / Zn mixtures. A glass diffusion cell was designed as a membrane system and system parameters were studied to enable the separation. According to the results; [MAL][NTf2] gave high extraction percentages of 71%, 92%, 79% and 88%, respectively, for La(III), Dy(III), Yb(III) and Lu(III), and showed selectivity for rare earth elements. Ionogels were obtained with the TEOS: formic acid molar ratio of 1 : 8, gelation time of 96 hours and aging time of 8 days. The ionogels synthesized in this way presented high surface area, porous structure, thermal stability and amorphous structure. In the membrane system studies, 24% Zn(II) was transferred to the receiving phase and seperated from Eu(III) by using Eu/Zn mixture in 1 M HCl as feed phase and 0.1 M Na2CO3 as receiving phase. Nowadays, on the separation of rare earth elements widely used in many different fields, the use of synthesized ionic liquid and developed ionogels is very important and promising for green chemistry.