A new type of symmetrical bis-crown ether is prepared by connecting dibenzo-18-crown-6 ether on both sides of the chromotropic acid , and then grafting the aforementioned bis-crown ether onto polyvinyl alcohol matrix to prepare a series of anion exchange membranes (AEMs), which their have high conductivity and strong alkali stability. These synthesized membranes were named B-C X% -P AEMs (x is the mass percentage of the symmetrical bis-crown ether (B–C)). Then, the chemical structure of aforementioned AEMs were verified by means of 1 H NMR, FT-IR and UV. Meanwhile, the OH − conductivity, alkaline stability and single cell performance of the synthesized membrane were also investigated. The results revealed that the conductivity of B–C 30% -P membrane is the highest at 80 °C (235 mS cm −1 ), and the power density is also the highest (197 mW cm −2 ), and the alkali stability of the membrane synthesized in this paper was also improved. The conductivity at 80 °C was only reduced by 4%, which was obtained by immersing the B–C 30% -P membrane immersed in 6 mol L −1 KOH solution for 168 h, which the aforementioned results proved that the synthesized membrane in this research had excellent OH − conductivity and alkaline stability.
With the gradual exhaustion of land mineral resources, oceans and lakes have attracted world attention because they are abundant in inorganic mineral resources including lithium, potassium, rubidium and cesium. Lithium is becoming the key material in manufacturing of primary and secondary batteries used in various portable devices and hybrid/electric vehicles. Rubidium has been widely applied inglobal positioning satellites, magneto-optic modulators, solid-state lasers, phosphors, and glass manufacturing. In this work, a novel dual-functional magnetic ion imprinting polymer (Fe 3 O 4 @SiO 2 @IIPs) powder was prepared using 12-crown-4 (12C4) and 18-crown-6 (18C6) as functional monomer, and characterized by FT-IR, elemental analysis, XRD, TGA, SEM and TEM. The adsorption performance of Fe 3 O 4 @SiO 2 @IIPs for simultaneous adsorption of lithium and rubidium from simulative salt lakes was evaluated by batches of experiments at various pH values, contact time, and initial concentrations. Kinetic experiments show that the adsorption process followed the pseudo second order kinetic model. Langmuir adsorption isotherm model and Freundlich adsorption equilibrium data were fitted; the results show that Langmuir isotherm model is more suitable for the adsorption process. Additionally, Fe 3 O 4 @SiO 2 @IIPs exhibit specificity towards Li(I) and Rb(I) and low competitive behavior with Na(I), K(I) and Mg (II). Additionally, the selectivity properties, reusability and adsorption thermodynamic were also investigated. The obtained results show that the prepared Fe 3 O 4 @SiO 2 @IIPs material remains high adsorption capacities after five cycles, exhibits excellent abilities to simultaneously and selectively recover Li + and Rb + and have a promising application in the simultaneous adsorption of lithium and rubidium ions.
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