Ceria Hollow Nanospheres Produced by a Template-Free Microwave-Assisted Hydrothermal Method for Heavy Metal Ion Removal and Catalysis

Abstract

Ceria hollow nanospheres composed of CeO2 nanocrystals were synthesized via a template-free and microwave-assisted aqueous hydrothermal method. This is a low-cost and environmentally benign method. The chemicals used are all environmentally benign materials (cerium nitrate, urea, and water). An Ostwald ripening mechanism coupled with a self-templated, self-assembly process, in which amorphous solid spheres are converted to crystalline nanocrystals and the latter self-assemble into hollow structures, was proposed for the formation of the hollow structures. The products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution TEM, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, and N2 adsorption−desorption methods. These ceria hollow nanospheres show an excellent adsorption capacity for heavy metal ions, for example, 22.4 mg g−1 for As(V) and 15.4 mg g−1 for Cr(VI). These values are significantly higher than reported data from other ceria nanostructures. These ceria hollow nanospheres are also excellent supports for gold nanoparticles, forming a Au/CeO2 composite catalyst. In CO oxidation, a 100% CO conversion was achieved at room temperature.

Extremely high arsenic removal capacity for mesoporous aluminium magnesium oxide composites

“…4c show that the highest AsIJV) adsorption capacity achieved for pure meso-Al-400 is 299 mg g −1 at the initial arsenic concentration of 1020 mg L −1 . This is much higher than previously reported values for metal oxide adsorbents, such as activated alumina, 43 mesoporous alumina, 18 ceria hollow nanospheres, 33 flowerlike α-Fe 2 O 3 , 27 and urchin-like α-FeOOH hollow spheres. 28 The high adsorption capacity of meso-Al-400 is probably due to its highly ordered mesopores, high surface area and pore volume.…”

The role of nanomaterials as effective adsorbents and their applications in wastewater treatment

“…The facileness of resource and ease of synthesis render nanosized ferric oxides to be low-cost adsorbents for toxic metal sorption. Since elemental iron is environmentally friendly, nanosized ferric oxides can be pumped directly to contaminated sites with negligible risks of secondary contamination [121,122]. Many reports discussed the influence of different parameters on the removal of metal ions by Fe 3 O 4 magnetic nanoparticles [47,123].…”

Three-dimensional-network Li3V2(PO4)3/C composite as high rate lithium ion battery cathode material and its compatibility with ionic liquid electrolytes

“…The microwave assisted hydrothermal method is widely used because of combination of advantages of the conventional hydrothermal method [26][27][28] and microwave solid-state synthesis [29,30], including morphology control, low cost, short reaction time, and high efficiency. Here, we successfully adopted a new synthesis route based on the microwave assisted hydrothermal method to obtain three dimensional (3D) Li 3 V 2 (PO 4 ) 3 /C micro-size network morphology.…”