An eco-friendly route for template-free synthesis of high specific surface area mesoporous CeO2 powders and their adsorption for acid orange 7

Abstract

An eco-friendly route was developed for the synthesis of mesoporous CeO₂ powders without any additional template. The original cerium precursors were separated from Ce³⁺ aqueous solution by (NH₄)₂CO₃ or Na₂CO₃ via a chemical precipitation method, then H₂O₂ was introduced to induce the phase transformation from original cerium precursors to CeO₂ precursors with initial porous structures, finally the crystallinities of CeO₂ precursors were improved by a hydrothermal treatment, meanwhile the mesoporous structures of final CeO₂ powders were formed. The BET surface areas of mesoporous CeO₂ powders synthesized using (NH₄)₂CO₃ and Na₂CO₃ as precipitants were 106.1 and 76.9 m² g⁻¹, respectively. Moreover, a mesoporous CeO₂ sample with BET surface area of 100.0 m² g⁻¹ was also synthesized using commercial Ce₂(CO₃)₃·xH₂O as an existing cerium precursor under the same conditions as control, which could shorten experimental processes and reduce costs. The oxidation-induced phase transformation from original cerium precursors to CeO₂ precursors with initial porous structures was the precondition for further forming of mesoporous structures of final CeO₂ powders during the hydrothermal process. These mesoporous CeO₂ powders showed the rapid and effective adsorption for acid orange 7 dye from simulated wastewater without pH pre-adjustment at room temperature. Furthermore, the adsorption capacities of these mesoporous CeO₂ powders for removal of acid orange 7 dye were determined according to the Langmuir linear fits.