Heterogeneous Mercury Reaction Chemistry on Activated Carbon

Figures & data

Figure 1. Schematic of the packed-bed reactor system.

Figure 2. Hg 4f core level XPS spectra for AC sorbents at various indicated conditions: (a–c) Br-AC sorbents and (d) virgin-AC sorbent.

Table 1. XPS binding energies for Hg⁰, Hg-Br, and HgO: References and Hg-containing brominated AC

	Hg 4f5/2	Hg 4f7/2	ΔE (eV)	Br 3d5/2
Reference 27
Hg^0	104.0	99.9	4.1	–
HgBr2	–	101.0	–	69.3
Hg2Br2	–	100.7	–	69.8
HgO	104.78	100.8	3.98	–
Hutson et al.14
DARCO Hg-LH	105.3	101.4	3.9	69.7
This study
DARCO Hg-LH	104.53	100.59	3.94	69.0

Figure 3. Computational domain of model C ribbon with exposed zigzag edge sites.

Figure 4. Surface configurations analyzed in the work presented here with stabilities ranging from the left (–945.113 eV) and center (–944.471 eV) to the right (–943.773 eV), with the configuration on the left being the most stable.

Table 2. Energies and bond distances of tested edge-site configurations

Structure	DFT Energy (eV)	Hg-C Distance (Å)	Br-C Distance (Å)	O-C Distance (Å)	Br-O Distance (Å)	Hg-O Distance (Å)	Hg-Br Distance (Å)
Hg-O-H-Br-H	−945.113	2.26	1.90	1.25	–	2.63	–
H-O-H-Br-Hg	−944.474	2.32	1.91	1.24	–	–	3.01
H-O-Hg-Br-H	−944.471	2.27	1.92	1.25	–	2.49	2.99
Hg-O-Br-H-H	−944.417	2.27	1.90	1.25	2.74	2.61	–
H-O-Br-H-Hg	−944.259	2.32	1.90	1.24	2.77	–	–
H-O-Br-Hg-H	−943.773	2.34	1.91	1.24	2.66	–	2.92

Figure 5. DOS showing the (a) s-, (b) p-, and (c) d-orbitals of Hg for various surface configurations compared with gas-phase Hg⁰ shown in black.

Figure 6. DOS showing the s-, p- (left axis), and d- (right axis) orbitals of surface atoms for (a) H-O-Hg-Br-H, (b) Hg-O-H-Br-H, and (c) H-O-Br-Hg-H.

Briggs , D. and Seah , M.P. 1996 . Practical Surface Analysis (Appendix 5) , New York : John Wiley & Sons .

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Hutson , N.D. , Attwood , B.C. and Scheckel , K.G. 2007 . XAS and XPS Characterization of Mercury Binding on Brominated Activated Carbon . Environ. Sci. Technol. , 41 : 1747 – 1752 .

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