An X-ray Photoelectron Spectroscopy Study of Surface Changes on Brominated and Sulfur-Treated Activated Carbon Sorbents during Mercury Capture: Performance of Pellet versus Fiber Sorbents

Abstract

This work explores surface changes and the Hg capture performance of brominated activated carbon (AC) pellets, sulfur-treated AC pellets, and sulfur-treated AC fibers upon exposure to simulated Powder River Basin-fired flue gas. Hg breakthrough curves yielded specific Hg capture amounts by means of the breakthrough shapes and times for the three samples. The brominated AC pellets showed a sharp breakthrough after 170−180 h and a capacity of 585 μg of Hg/g, the sulfur-treated AC pellets exhibited a gradual breakthrough after 80−90 h and a capacity of 661 μg of Hg/g, and the sulfur-treated AC fibers showed no breakthrough even after 1400 h, exhibiting a capacity of >9700 μg of Hg/g. X-ray photoelectron spectroscopy was used to analyze sorbent surfaces before and after testing to show important changes in quantification and oxidation states of surface Br, N, and S after exposure to the simulated flue gas. For the brominated and sulfur-treated AC pellet samples, the amount of surface-bound Br and reduced sulfur groups decreased upon Hg capture testing, while the level of weaker Hg-binding surface S(VI) and N species (perhaps as NH 4 + ) increased significantly. A high initial concentration of strong Hg-binding reduced sulfur groups on the surface of the sulfur-treated AC fiber is likely responsible for this sorbent's minimal accumulation of S(VI) species during exposure to the simulated flue gas and is linked to its superior Hg capture performance compared to that of the brominated and sulfur-treated AC pellet samples.

In Situ Emergency Disposal of Liquid Mercury Leakage by Fe-Containing Sphalerite: Performance and Reaction Mechanism

“…The Zn 2p 3/2 binding energy of sphalerite mainly appeared at 1021.7 eV (shown in Figure b), which was attributed to Zn 2+ in ZnS or ZnO . The S 2p binding energies of sphalerite mainly centered at 161.5 and 162.7 eV (shown in Figure c), which were assigned to S 2– and S 2 2– , respectively. , Furthermore, the S 2p binding energies centered at approximately 164, 167, and 169 eV corresponding to S 0 , SO 3 2– , and SO 4 2– cannot be observed on sphalerite . O species on sphalerite can be clearly observed at 531.9 eV (shown in Figure d).…”

Role of inherent active constituents on mercury adsorption capacity of chars from four solid wastes

“…According to Fig. 6C, the spectrum of fresh T6 has only one peak for Si at 103.1 eV [28,29]. After mercury adsorption test, two new peaks appear at 101.1 and 104.7 eV, which represents Hg 2+ [30,31].…”

“…The effect of NH 4 Cl impregnation on mercury removal is shown in Fig. 4 [28,29]. However, after the mercury adsorption testing, a new peak appears at 104.3 eV representing oxidized mercury (Hg 2+ ) [30,31].…”

Elemental mercury removal by the modified bio-char from medicinal residues

“…As shown in Table 6, the equilibrium adsorption capacity of CACs ranges from 94.0 µg/g to 207.0 µg/g [37][38][39][40][41]. The data in Table 6 indicates that the S BET of sorbents is not closely related to Hg 0 capture capacity.…”