Review of elemental mercury (Hg0) removal by CuO-based materials

Mercury emission has become a great environmental concern because of its high toxicity, bioaccumulation, and persistence. Adsorption is an effective method to remove Hg-0 from coal-fired flue gas, with adsorbents playing a dominant role. Extensive investigations have been conducted on the use of CuO-based materials for Hg-0 removal, and some fruitful results have been obtained. In this review, we summarize advances in the application of CuO-based materials for Hg-0 capture. Firstly, the fundamentals of CuO, including its crystal information and synthesis methods, are introduced. Then, the Hg-0 removal capability of some typical CuO-based adsorbents is discussed. Considering that coal-fired flue gas also contains a certain amount of NO, SO2, H2O, NH3, and HCl, the impacts of these species on adsorbent Hg-0 removal efficiency are summarized next. By generalizing the mechanisms dominating the Hg-0 removal process, the rate-determining step and the key intermediates can be discovered. Apart from Hg-0, some other air pollutants, such as CO, NOx, and volatile organic compounds (VOCs), account for a certain portion of flue gas. In view of their similar abatement mechanisms, simultaneous removal of Hg-0 and other air pollutants has become a hot topic in the environmental field. Considering the Hg-0 re-emission phenomena in wet flue gas desulfurization (WFGD), mercury capture performance under different conditions in this device is discussed. Finally, we conclude that new adsorbents suitable for long-term operation in coal-fired flue gas should be developed to realize the effective reduction of mercury emissions.

Automated summary

Mercury emission is an environmental concern due to its high toxicity, bioaccumulation, and persistence. This review summarizes the advances in the application of CuO-based materials for Hg-0 capture and discusses the simultaneous removal of other air pollutants. The study concludes that new adsorbents suitable for long-term operation in coal-fired flue gas should be developed to effectively reduce mercury emissions.