Cui Wei,Wang Shixing,Peng Jinhui,Zhang Libo,Zhang Gengwei
Abstract We prepared the catechol-functionalized nanosilica for adsorption of germanium (Ge) ions from aqueous media. The functionalized nanosilica was characterized by FTIR, TGA, TEM, BET, and XPS. The influence of pH, Ge initial concentration, and time of the adsorption process was investigated. Under the optimum condition, the maximum adsorption capacity of Ge ions was 0.048 mg m −2 at pH 4.5. The adsorption mechanism is the chelating interaction between hydroxyl and Ge(OH) 4 . The functionalized nanosilica was able to selectively adsorb Ge ions from tellurium(IV) and boron. Langmuir isotherm was found to better fit the experiment data rather than Freundlich isotherm. The kinetics of the adsorption process of Ge ions on the functionalized nanosilica was investigated using the pseudo-first-order and pseudo-second-order models, and the results indicated that the pseudo-second order equation model provided the best correlation with the experimental results. Graphical Abstract
Hanjun Wu,Yang Zhang,Zhenyue Zhang,Wenda Guo,Wendou Chen,Guoqing Feng,Junxia Yu,Ruan Chi,Zhiquan Pan
In this work, a germanium ion-imprinted polymer (Ge-IIP) based on α-bromobutyric intercalation-modified hydrotalcite was synthesized by atom transfer radical polymerization and applied for the capture of germanium ions from wastewater. In particular, layered hydrotalcite as a skeleton support induced in situ polymerization of Ge-IIPs to form graded pores, and an α-bromobutyric interlayer was also used as an initiator to induce graft polymerization of functional monomers of 3-dihydroxypropyl-2-acrylate to form strong coordination cavities for germanium ions. Batch experiment results showed that Ge-IIPs could effectively capture germanium at a pH value of 3, and the maximum adsorption capacity was up to 55.18 mg·g–1. The adsorption kinetics and isotherms indicated that the capture of germanium was consistent with a pseudo-second-order kinetic model and a Freundlich isotherm model. The distribution coefficient values of Ge(IV) adsorption by Ge-IIPs in a coexisting metal ion solution were as high as 25 231.36 mL·g–1, indicating significant capture selectivity. In addition, Ge-IIPs showed good reusability, and the uptake rate of germanium could still reach 98.45% after 5 cycles. Furthermore, density functional theory calculation indicated that the efficient selective capture of germanium by Ge-IIPs may be attributed to the ion exchange and surface complexation between germanium ions and the abundance of o-hydroxyl groups in the Ge-IIP structure. The excellent salt tolerance and adsorption selectivity of Ge-IIPs provide the possibility for its practical application in germanium recovery from wastewater.
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