Adsorption of Indium(III) Ions from an Acidic Solution by Using UiO-66

Abstract

Considering environmental friendliness and economic factors, the separation and extraction of indium under acidic conditions are of great significance. In this research, metal-organic frameworks (MOFs) of UiO-66 were successfully prepared and used for the separation and adsorption of indium. The properties of UiO-66 were structurally characterized using powder X-ray diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller surface area analyzer (BET), thermogravimetric analysers (TGA) and Scanning Electron Microscope (SEM). The results show that UiO-66 can resist acid and keep its structure unchanged, even at a strong acidity of pH 1. The adsorption performance of UiO-66 to indium (III) was also evaluated. The results show that the adsorption process of indium ions was by the Langmuir adsorption isotherm, with a maximum adsorption capacity of 11.75 mg·g−1 being recorded. The adsorption kinetics experiment preferably fits the second-order kinetic model. A possible mechanism for the adsorption of In(III) by UiO-66 was explored through X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared analysis(FT-IR). It was concluded that the C=O of free –COOH of UiO-66 was involved in the adsorption of In(III) by cation exchange. This study indicates, for the first time, that UiO-66 can be applied as an acid-resistant adsorbent to recover indium (III).