Growing public awareness of the environmental impact of coal combustion has raised serious concerns about the various hazardous trace elements produced by coal firing. Arsenic deserves special attention due to its toxicity, volatility, bioaccumulation in the environment, and potential carcinogenic properties. As the main anthropogenic source of arsenic is coal combustion, its behavior in power plants is of concern. Unlike mercury, arsenic behavior in coal combustion has not been subjected to systematic, in-depth research. Different researchers have reached opposing conclusions about the behavior of arsenic in combustion systems and as yet there is relatively little research on arsenic-removal technologies. In this paper, the volatilization, transformation, and emission behavior of arsenic and its removal technologies are discussed in depth. Factors affecting the volatilization characteristics of arsenic are summarized, including temperature, pressure, mode of occurrence of arsenic, coal rank, mineral matter, and the sulfur and chlorine content of the fuel. The behavior of arsenic during oxy-fuel combustion and the effect of combustion atmosphere (O2, CO2, SO2 and H2O(g)) are also reviewed in detail. In order to better understand the pathway of arsenic in a power plant environment, a particular focus in this work is the transformation mechanism of ultra-fine ash particles and the partitioning behavior of arsenic. Finally, the effects of air pollution control devices (APCDs) on arsenic emissions are examined, along with the

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The volatilization characteristics of arsenic in different coals at 600−1500 °C were studied on an isothermal reaction system. Through thermogravimetric analysis similar to that used for coal analysis, the mass loss and mass loss rate of arsenic for coal samples were determined. Sequential chemical extraction method was used to measure the mode of occurrence of arsenic in the coals. TG-MS techniques were also carried out to study the relationship between sulfur and arsenic. Results show that the volatilization proportion of arsenic increases with temperature and 53− 99% of the total arsenic in coal is vaporized in the combustion zone at PC conditions (1500 °C). Coals with higher arsenic concentrations (As > 4 μg/g) tend to have larger arsenic volatility proportions than coals with lower arsenic concentrations (As < 4 μg/g) at a given temperature. In addition, three volatility zones with two mass loss rate peaks of arsenic are observed in all coals during coal combustion. Before 600 °C, the evaporation of organic-bound arsenic dominates; then the first arsenic mass loss peak at 800−900 °C is mainly from the decomposition or oxidation of arsenic in sulfide forms. The second peak after 1000 °C is probably generated through the decomposition of arsenates. For As > 4 μg/g coals, the first peak is higher than the second peak due to the larger proportion of sulfide-bound arsenic, while the second mass loss peak of arsenic is higher in As < 4 μg/g coals due to the larger proportion of arsenates. Furthermore, thermodynamic analysis by HSC chemistry6.0 software were carried out to prove that arsenates, like Ca 3 (AsO 4 ) 2 , FeAsO 4 , and Mg 3 (AsO 4 ) 2 , are thermally stable and could only decompose at relatively high temperatures.

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