Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces

Influence of a CO2-enriched flue gas on mercury capture by activated carbons

“…CO is derived from phenols, ethers and carbonyl/quinone groups [36,37]. Previous studies have suggested that oxygen functional groups, such as, lactone and carbonyl, may be active sites that favor mercury adsorption whereas phenol groups inhibit mercury adsorption [15,28,38,39]. To identify the functional groups on the carbon surface and to clarify the modifications that occur during the process due to interaction with the components of the oxy-combustion atmosphere, the TPD profiles of (i) the raw materials (RB3 and RBHG3), (ii) RB3 and RBHG3 after being subjected to an atmosphere free of mercury (RB3/RBHG3 treat.oxycomb), (iii) the carbons subjected to the same atmosphere containing Hg (RB3/RBHG3 oxycomb_Hg), and (iv) the solids obtained after being subjected to an oxy-combustion atmosphere but now in an inert atmosphere containing mercury (RB3/RBHG3 treat.oxycomb_Hg), were evaluated and compared (Figs.…”

“…phenols (I) which will facilitate the electron transfer process, i.e. mercury oxidation [15,28,38,39]. To explain the decrease in mercury retention in activated carbons in the oxy-combustion atmosphere different competitive reactions need to be taken into consideration: (i) the high proportion of CO 2 present in the gas composition might be occupying a part of activated carbon microporous structure competing for the same adsorption sites as mercury [22], (ii) the H 2 O molecules in the flue gas (in oxy-combustion they may be present in concentrations of up to 30%) might be adsorbed into the micropore structure of the activated carbon reducing the number of active sites for mercury adsorption [12,24,[43][44][45], (iii) a higher proportion of oxidation of SO 2 to SO 3 that could occur during oxy-combustion [33,46] will inhibit mercury adsorption because SO 3 will be competing with mercury for the same binding sites [19,25,30,47].…”

Effects of Multi-component Flue Gases on Hg0 Removal over HNO3-Modified Activated Carbon

“…7,8 We also recently reported that AC with a greater Hg 0 removal performance can be developed by treating ACs with HNO 3 to avoid the secondary emissions of hydrogen halides, which severely corrode pipes. 9 The Hg 0 removal performance was strongly affected by the flue gas compositions.…”

Influence of activated carbon surface oxygen functionality on elemental mercury adsorption from aqueous solution

“…Adsorbed Hg(0) was desorbed as Hg(II), lending support to the oxidation hypothesis. In a theoretical study, Liu et al [23] concluded that lactone and carbonyl favor Hg(0) adsorption, while phenol and carboxyl reduce Hg(0) capture. The role of C(O) complexes in aqueous Hg(0) adsorption is not defined in literature.…”