Catechol-functionalized nanosilica for adsorption of germanium ions from aqueous media

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 pseudosecond order equation model provided the best correlation with the experimental results. Graphical Abstract& Shixing Wang

Catechol-Functionalized Chitosan Synthesis and Selective Extraction of Germanium (IV) from Acidic Solutions

“…21,22 Catechol-functionalized nanosilica showed a maximum capacity of 6.08 mg/g at pH 4.5 and was selective for Ge against B and Te with SFs of 2.1 and 74. 21 Catechol-formaldehyde resin was selective for Ge over Si and Zn with SFs of 28 and 5, respectively (at pH 6 and 1 g resin/L), but had a capacity of <2 mg/g. 22 However, very limited data exist on catechol-functionalized adsorbents with higher adsorption capacity and performance against competitive ions in acidic mixtures usually found in the industry.…”

Non-Dispersive Extraction of Ge(IV) from Aqueous Solutions by Cyanex 923: Transport and Modeling Studies

“…Gasification coal fly ashes (GCFAs) containing germanium can be leached with water to dissolve germanium as water-soluble species [5]. Several processes have been developed to recover and separate germanium from impurities such as precipitation [6], flotation [7], ion-exchange [8], distillation [2], adsorption [9], liquid-liquid extraction (LLX) [10], and supported liquid membrane (SLM) [11][12][13]. Among these techniques, the LLX processes have been extensively applied to separate germanium from aqueous solutions [14,15].…”

Non-Dispersive Extraction of Ge(IV) from Aqueous Solutions by Cyanex 923: Transport and Modeling Studies

“…Gasification coal fly ashes containing germanium can be leached with water to dissolve germanium as water-soluble species [6]. Several processes have been developed to recover and separate germanium from impurities such as precipitation [7], flotation [8], ion-exchange [9], distillation [3], adsorption [10], and liquid-liquid extraction (LLX) [11]. Among these techniques, the LLX processes have been extensively applied to separate germanium from aqueous solutions [12].…”