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Sol–Gel Derived Benzo-Crown Ether-Functionalized Silica Gel for Selective Adsorption of Ca2+ Ions
journal contribution
posted on 2019-03-15, 11:18 authored by Nan You, Yue-Xian Song, Hai-Rong Wang, Li-Xia Kang, Hong-Tao Fan, Hui YaoBenzo-crown
ether-functionalized silica (BCES) was prepared by
the combination of the sol–gel process and the Schiff base
reaction, characterized by Fourier transmission infrared spectroscopy,
scanning electron microscopy, and N2 adsorption–desorption,
and used for the selective adsorption of Ca2+ ions. The
adsorption amounts of the BCES for Ca2+ ions were independent
of pH in the range of 5–10. Adsorption equilibrium was performed
within 60 min. The adsorption capacity of the BCES for Ca2+ ions was found to be 40.6 mg g–1 at 298 K. The
high selectivity of the BCES for Ca2+ ions with respect
to the other alkali and alkaline earth metals was attributed to the
high affinity between Ca2+ ions and crown ether. The adsorption/desorption
cycle of the BCES could be up to five times. Langmuir and pseudo-second-order
equations provided good correlation for the adsorption of Ca2+ ions. The thermodynamics of Ca2+ ions/BCES system indicates
spontaneous and endothermic nature.