Recovery of tellurium from aqueous solutions by adsorption with magnetic nanoscale zero-valent iron (NZVFe)

Waste tellurium cadmium solar cells, as one of the world's fastest growing electronic waste, contain abundant valuable rare elements, offering potential for the prospects of resource exploitation and separation. Herein, we proposed a facile magnetic adsorption separation of tellurium from aqueous solutions by nanoscale zero-valent iron. As the precursor of tellurium adsorbents, the nanoscale FeOOH were first prepared by facile hydrothermal reaction. Then, magnetic nano zero-valent iron NZVFe was obtained by thermal reduction of FeOOH in the hydrogen atmosphere. The physical and chemical properties of magnetic NZVFe were characterized by a number of analytical techniques including scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and N-2 adsorption-desorption. The results indicated that the obtained NZVFe exhibit high specific surface areas (64.43 m(2)/g), uniform pore sizes (2.80 nm), and high pore volumes (0.045 cm(3)/g). XPS results indicated that the surfaces of NZVFe were covered by a layer of tellurium, implying the successful extraction of tellurium. Parameters such as initial tellurium concentration, solution pH, interfering ions, adsorption times and adsorption temperatures that affect the adsorption efficiency of tellurium were studied. Due to the highly accessible surface and fully exposed active sites of NZVFe, the samples exhibit excellent adsorption capacity of 190 mg/g towards tellurium in water, and separation efficiency can reach > 95%. As a clean and high-efficient adsorbent, NZVFe has tremendous potential to handle and recycle cadmium telluride solar cells waste.