球形MnO_(2)·0.5H_(2)O提锂性能及其机理研究

Performance and Mechanism of Recovering Lithium from Aqueous Solution by Spherical MnO_(2)·0.5H_(2)O

考察了形貌对尖晶石型锂离子筛吸附剂MnO_(2)·0.5H_(2)O吸附性能的影响。实验证明,反应物Mn_(2)O_(3)的形貌在很大程度上决定了前驱体及其吸附剂的形貌。采用XRD、SEM、TEM、FT-IR、XPS和N_(2)吸附—解吸等温线等对样品进行了表征。表征和吸附实验结果表明,与立方形锂离子筛相比,球形锂离子筛具有较高的吸附容量(42.46 mg/g),同时对溶液中的Li^(+)具有较高的选择性。表面脱质子和离子交换过程的共同作用增强了离子筛型吸附剂的提锂Li^(+)性能。此外,本文对Li_(1.6)Mn_(1.6)O_(4)与MnO_(2)·0.5H_(2)O的吸附—解吸机理进行了解释。

The influence of morphology on the adsorption capacity of spinel-structured MnO_(2)·0.5H_(2)O lithium ion-sieves(LISs)prepared by the treatment of a Li_(1.6)Mn_(1.6)O_(4)precursor in HCl was experimentally investigated.The obtained samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Fourier-transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),and N_(2)adsorption-desorption isotherms.Spherical LISs were demonstrated to have a higher adsorption capacity(up to 42.46 mg/g)and selectivity toward Li^(+) in solution than their cubic counterparts.As a result,the morphology of reactant Mn_(2)O_(3)was determined to largely determine the morphology of the precursor prepared by a typical two-step solid-phase reaction and its corresponding adsorbent.Additionally,the results presented here indicate that both surface deprotonation and ion-exchange processes of the as-prepared sieve-type adsorbent contribute to its enhanced Li+adsorption performance.