Mechanism evaluation and extraction ability of lithium ion by in-situ solvent formation microextraction method (ISFME) using ionic liquids in magnesium-rich real aqueous media

Easy and selective separation of lithium ions from other self-accompanying ions in nature such as magnesium, it is still a challenge for researchers due to their similar chemical properties. Here, the simple in situ solvent extraction method (ISFME) derived from the homogeneous liquid-liquid extraction method (HLLME) using ionic liquids as the organic phase is described. The organic phase containing ionic liquid of 1-hexyl-3-methylimidazolium hexafluorophosphate [C6mim][PF6] and a phosphorous ligand (extracting agent) called n-tributyl phosphate (n-TBP). To optimize lithium ion extraction conditions, analytical parameters such as pH of the sample solution, amount of ionic liquid in the organic phase, ratio of organic to aqueous phase (O/A), amount of hexafluorophosphate anion as counter-ion and centrifugation conditions for phase separation were studied and optimized. Under the best conditions, the method is capable to extraction 95% of lithium ions in the presence of very high magnesium concentrations (about 100 times the concentration of lithium ions). The mechanism of lithium ion extraction by ionic liquid as well as the metal-ligand extraction ratio (1:1) have been investigated using conventional techniques such as ultraviolet spectroscopy (UV-Vis) and Fourier Transform Infrared spectroscopy (FTIR). It is also the method was able to determination of lithium ions in different real samples, successfully.