Dual-template crown ether-functionalized hierarchical porous silica: Preparation and application for adsorption of energy metal lithium

Lithium is the lightest energy metal element on earth and it has applications in lithium batteries and nuclear fusion. With the development of high-tech and widespread applications of lithium, the demand for lithium continues to increase. In this work, a hierarchical porous lithium adsorbent (2M12C4-HPS) was synthesized from a precursor of hierarchical porous silica (HPS), the HPS being obtained via a dual-template technique. The microstructure and morphology of 2M12C4-HPS were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction and nitrogen adsorption-desorption measurements. The obtained hierarchical porous 2M12C4-HPS containing two kinds of pores with different sizes (peaking at about 2.01 and 7.82nm) has a high specific surface area (1143.56m(2)g(-1)). Fourier transform infrared spectroscopy and thermogravimetric analysis were used to confirm the surface organic functional groups of 2M12C4-HPS, indicating that the functional group 2-methylol-12-crown-4 (2M12C4) was grafted on HPS successfully. The lithium adsorption properties, kinetics and isotherms of 2M12C4-HPS were investigated. The adsorption kinetics can be described by the pseudo-second-order kinetic model and the adsorption isotherms well fit the Langmuir isotherm equation. In addition, 2M12C4-HPS exhibited excellent specificity towards Li+. And the maximum adsorption rate of 2M12C4-HPS is up to about 94.34%. The obtained results indicate that 2M12C4-HPS has a broad commercial application prospect for adsorption of lithium.