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