Nonaqueous Sol−Gel Synthesized Hierarchical CeO₂ Nanocrystal Microspheres as Novel Adsorbents for Wastewater Treatment

Abstract

Hierarchical CeO2 nanocrystal microspheres were synthesized with a nonaqueous sol−gel method at a low temperature of 120 °C. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and nitrogen sorption measurements. The adsorption performances of hierarchical CeO2 nanocrystal microspheres were tested with the batch removals of typical pollutants of Cr(VI) and rhodamine B from simulated wastewater. It was found that the nanostructured CeO2 could effectively remove Cr(VI) without pH preadjustment. The Freundlich adsorption isotherm was applicable to describe the removal processes. Kinetics of the Cr(VI) removal was found to follow pseudosecond-order rate equation. Furthermore, the as-prepared and Cr(VI)-adsorbed hierarchical CeO2 nanocrystal microspheres were carefully analyzed by X-ray photoelectron spectroscopy (XPS). On the basis of the XPS results, a possible mechanism of Cr(VI) removal with hierarchical CeO2 nanocrystal microspheres was proposed. Moreover, these nonaqueous sol−gel synthesized hierarchical CeO2 nanocrystal microspheres also exhibited remarkable ability to remove rhodamine B, suggesting they are promising absorbents for wastewater treatment.

Influence of the Incorporation of CeO2 Nanoparticles on the Ion Exchange Behavior of Dodecylsulfate Doped Polypyrrole Films: Ac-Electrogravimetry Investigations

“…These materials were extensively studied owing to their many distinctive characteristics and applications such as catalysts in the fuel cell technology [14], gas sensor [15], catalytic wet oxidation [16][17], oxygen storage and release [18], wastewater treatment [19] or photo-catalytic oxidation of water [20]. 4 In our work, CeO 2 oxide was selected as it is expected to provide its strong oxidizing power to the resulting PPy-DS/CeO 2 NPs nanocomposite materials.…”

Catalytic photodegradation of Congo red in aqueous solution by Ln(OH)3 (Ln = Nd, Sm, Eu, Gd, Tb, and Dy) nanorods

“…Consequently, additional studies are warranted in order to gain a better understanding of the factors governing the photoactivity of Ln(OH) 3 nanostructures. Organic dyes removal in wastewater has attracted considerable attention because of their long-term environmental toxicity and short-term public health damage [23,24]. Congo red [1-naphthalene sulfonic acid, 3,30-(4,40-biphenylenebis (azo)) bis (4-amino-)disodium salt] with two azo bonds ( N N ) chromophores in its molecular structure is a well-known class of azo dyes that are of high toxicity and even carcinogenic to the animals and human and they are not readily degradable.…”

Ultra-simple synthetic approach to the fabrication of CeO2–ZrO2 mixed nanoparticles into homogeneous, domain, and core–shell structures in mesoporous spherical morphologies using supercritical alcohols

“…In order to achieve high performance, controlling the composition, topology, and morphology of CeO 2 -ZrO 2 composites at the nano level is very important. To this end, much effort has been applied towards the development of synthetic methodologies to control their structures and morphologies; these include sol-gel [10,11], precipitation [12,13], microemulsion [14], hydrothermal [15,16], supercritical solvent [17], high-temperature solid state reaction [18], high-energy mechanical mixing [19], and flame spray [20] methods. However, multi-step reactions that include calcination, as well as a long reaction time, are usually required to obtain higher-ordered nanostructures such as spherical, cubic, and multi-layered structures.…”