Hierarchical Ag-SiO2@Fe3O4 magnetic composites for elemental mercury removal from non-ferrous metal smelting flue gas

Hierarchical Ag-SiO2@Fe3O4 magnetic composites were selected for elemental mercury (Hg-0) removal from non-ferrous metal smelting flue gas in this study. Results showed that the hierarchical Ag-SiO2@Fe3O4 magnetic composites had favorable Hg-0 removal ability at low temperature. Moreover, the adsorption capacity of hierarchical magnetic composite is much larger than that of pure Fe3O4 and SiO2@Fe3O4. The Hg-0 removal efficiency reached the highest value as approximately 92% under the reaction temperature of 150 degrees C, while the removal efficiency sharply reduced in the absence of O-2. The characterization results indicated that Ag nanoparticles grew on the surface of SiO2@Fe3O4 support. The large surface area of SiO2 supplied efficient reaction room for Hg and Ag atoms. Ag-Hg amalgam is generated on the surface of the composites. In addition, this magnetic material could be easily separated from fly ashes when adopted for treating real flue gas, and the spent materials could be regenerated using a simple thermal-desorption method. (C) 2018 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.