Potential Hazards of Brominated Carbon Sorbents for Mercury Emission Control

Abstract

Mercury is a toxic air pollutant, emitted from the combustion of coal. Activated Carbon (AC) or other carbon sorbent (CS) injection into coal combustion flue gases can remove elemental mercury through an adsorption process. Recently, a brominated CS with biomass ash as the carbon source (Br-Ash) was developed as an alternative for costly AC-based sorbent for mercury capture. After mercury capture, these sorbents are disposed in landfill, and the stability of bromine and captured mercury is of paramount importance. The objective of this study is to determine the fate of mercury and bromine from Br-Ash and brominated AC after their service. Mercury and bromine leaching tests were conducted using the standard toxicity characteristic leaching procedure (TCLP). The mercury was found to be stable on both the Br-Ash and commercial brominated AC sorbents, while the bromine leached into the aqueous phase considerably. Mercury pulse injection tests on the sorbent material after leaching indicate that both sorbents retain significant mercury capture capability even after the majority of bromine was removed. Testing of the Br-Ash sorbent over a wider range of pH and liquid:solid ratios resulted in leaching of <5% of mercury adsorbed on the Br-Ash. XPS analysis indicated more organically bound Br and less metal-Br bonds after leaching.

Structural defects in 2D MoS2 nanosheets and their roles in the adsorption of airborne elemental mercury

“…Currently, activated carbon is commercially applied in power plants for elemental mercury removal [14]. However, the spent carbon is still a hazardous material and may compromise fly ash as a saleable by-product [15][16][17]. Therefore, the development of alternative non-carbon-based sorbents is necessary for mercury emission control in industry [18][19][20].…”

A Magnetically Recoverable Fe3O4–NH2–Pd Sorbent for Capture of Mercury from Coal Derived Fuel Gas

“…Previously, a number of sorbents have been used for Hg° removing in the literature. It has been found that the activated carbon and fly ash 9 , 10 , particularly the activated carbon impregnated with sulfur 11 , 12 , chlorine 13 , 14 , iodine 15 and bromine 16 , 17 , showed a high efficiency in removing mercury. However, these previously studies also showed that the activated carbon and fly ash sorbents still suffer from practical utilization in separation and recycling besides the potential contamination caused by the converted products.…”

A novel nano-sized Co3O4@C catalyst derived from Co-MOF template for efficient Hg0 removal at low temperatures with outstanding SO2 resistance

“…(Pacyna et al, 2006;Ji et al, 2018;Zhang et al, 2020b) Nowadays, injecting activated carbon is the most mature technology for Hg 0 removal and has been employed by many coal-fired power plants. (Bisson and Xu, 2015;Xu et al, 2018) Activated carbon can adsorb Hg 0 , but its low efficiency leads to high operation costs. (Cao et al, 2017) Therefore, the desire for more efficient and low-cost Hg 0 removal agents has focused research on catalysts.…”