Extraction of lithium ions from salt lake brine using magnetic ionic liquid: Kinetic and equilibrium studies

In this study, 1-hexyl-3-methylimidazolium [C(6)mim(+)] as cation and bis(trifluoromethylsulfonyl)imide [NTf2-] as anion of ionic liquid (ILs) using the neutral tributyl phosphate (TBP) and magnetic ionic liquid (MNP@ILs) were developed for efficient extraction of lithium ions (Li+) from Salt Lake Brine. The synthesized MNPs@ILs adsorbent was characterized using Fourier transform infrared spectroscopy, vibrating sample magnetometer, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. The effective parameters on lithium ions extraction process were studied including solution pH (~7), adsorbent dosage (100 & 300 mg) and extraction time (30 & 120 min). The extraction efficiency of lithium ion was 94%, 78% for ILs and MNP@ILs under the optimal conditions. The adsorption rate, adsorption capacity and mechanism are examined with applying the kinetic, isotherm and free energy models on experimental data, respectively. The Langmuir isotherm proposed adsorption capacity of 62.5 mg/g and 20.8 mg/g for ILs and MNPs@ILs, respectively. This indicated a monolayer adsorption pattern for lithium ions over MNPs@ILs and multilayer pattern over ILs. The free energy model is suggested a physical sorption mechanism for lithium ions. The obtained results are performed the green ILs and novel MNPs@ILs can be used as an alternative extractant for Li+ from Salt Lake Brine.