Promotion effect of Cu doping on mercury removal properties of magnetic MnFe2O4 materials with high adsorption capacity

Abstract

In this study, a simple method combining sol-gel and impregnation techniques was employed to synthesize magnetic Cu/MnFe2O4. The resulting material demonstrated outstanding efficiency in removing mercury, achieving over 90% at reaction temperatures ranging from 150 °C to 200 °C. Through Cu incorporation, the Hg0 removal performance of Cu0.15MnFe was significantly enhanced, leading to a high adsorption capacity of 70.1 mg/g. This surpasses the capabilities of many previously reported adsorbents and holds great potential for enhancing the stability of Hg recovery efficiency. Furthermore, the presence of O2, HCl, and NO further improved the Hg0 removal. Conversely, H2O had an mild inhibitory effect on Hg0 removal. Additionally, the introduction of Cu noticeably mitigated the inhibitory impact of SO2 on mercury removal characteristics and alleviated the issue of SO2 poisoning in adsorbents. The primary active sites responsible for the oxidation of elemental mercury are the redox reaction between Cu2+/Cu+ and Mn3+/Mn2+, and adsorbed oxygen species. Through the oxidation process, Hg0 is primarily converted into various compounds, including HgO, Hg(NO3)2, HgCl2, and HgSO4. As a result, the prepared magnetic recyclable adsorbent, with its high mercury adsorption capacity, exhibits promising prospects for industrial application in the low-temperature removal of Hg0 from coal-fired flue gas.