Charge modulation of selenospinel by Mn modification to generate unsaturated Se sites for highly efficient mercury capture

Abstract

Selenospinel has been regarded as a promising adsorbent for Hg0 capture from the flue gas, and the unsaturated Se1− site is one of the critical factors affecting the Hg0 capture performance. The regulation of selenospinel to generate more unsaturated Se1− sites is a great challenge for the enhanced Hg0 capture performance. Herein, a charge modulation strategy of selenospinel via high-valance Mn modification was proposed to generate the unsaturated Se1− sites for efficient and fast Hg0 capture. The unsaturated Se1− sites showed the high affinity towards Hg0 and decreased the energy barrier of HgSe formation. As a result, Mn modified CuCo2Se4 spinel showed the ultra-high Hg0 adsorption capacity (125.86 mg·g−1) and rate (10.24 mg·g−1∙h−1), which were greatly higher than the previously reported adsorbents. Additionally, Mn modified CuCo2Se4 exhibited the excellent resistance towards SO2 and H2O, making it highly suitable for the practical application. DFT calculation verified the important role of unsaturated Se1− sites derived from Mn modification in the Hg0 removal process. This study developed a metal modification strategy to modulate the charge distribution of selenospinel for Hg0 capture, offering a guidance for adsorbent design in the environmental protection.