Review of elemental mercury(Hg^(0))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,SO_(2),H_(2)O,NH_(3),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.