Using the composite material of GO and g-C3N4 nanosheets as substrate to in-situ grow Co3O4 nanosheets for efficient Hg0 removal. (15th May 2023) - Wang, Xinxin
Graphical abstract: Highlights: Co3 O4 nanosheet was grown in the interlayer space of GO and g-C3 N4 nanosheet. GO can improve electron transfer from g-C3 N4 to Co3 O4 . The Hg 0 removal efficiency of Co3 O4 /GCN-5 was about 95 % at 200 °C. XPS and Hg 0 desorption experiment were performed to study adsorption mechanism. Abstract: Chemisorption is an effective method to remove Hg 0 from coal-fired flue gas. During this process, Hg 0 will convert to Hg 2+ and be solidified on sorbent surface. The number of adsorption sites and the electron transfer between Hg 0 and sorbents play an important role in the removal process. In the present work, GO with a rapid electron transfer was compounded with NS-g-C3 N4 to improve the electron donating ability of NS-g-C3 N4 . After that, Co3 O4 nanosheets were grown in-situ in the interlayer space of GO and NS-g-C3 N4 composites. A series of sorbents were successfully synthesized by changing GO concentration. SEM and TEM results show that the corresponding Co3 O4 /GCN (GCN denote the GO and NS-g-C3 N4 composites) sorbent has better Co3 O4 nanosheet dispersibility when GO concentration is 5 mg/mL. This results in a large amount of chemisorbed oxygen, which is favor to the oxidation of Hg 0 to HgO. In addition, XPS results show that the interaction between Co3 O4 and GCN give a rapid electrons transfer from GCN to Co3 O4, thus improving the activation of gaseous oxygen. Therefore, Co3 O4 /GCN-5 has excellent Hg 0 removal efficiency of about 95 % at 200 °C and high stability under different flue gas conditions. A probable reaction path way was deduced by the results of XPS and Hg 0 adsorption–desorption experiment.