The effect of H2O on formation mechanism of arsenic oxide during arsenopyrite oxidation: Experimental and theoretical analysis
The effect of H2O on formation mechanism of arsenic oxide during arsenopyrite oxidation: Experimental and theoretical analysis
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DOI：
10.1016/j.cej.2019.123648
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发表时间：
2020-07
影响因子：
15.1
通讯作者：
Chan Zou;Chunbo Wang;Liang Chen;Yue Zhang;Xing Jiaying;E. Anthony
中科院分区：
文献类型：
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作者：
Chan Zou;Chunbo Wang;Liang Chen;Yue Zhang;Xing Jiaying;E. Anthony
通过实验和第一性原理密度泛函理论（DFT）研究了水对砷释放行为的影响。实验结果表明，硫化物结合的砷是煤中存在的主要形式，水对煤燃烧过程中砷的释放有积极的影响。通过DFT计算，探讨了水对砷氧化的影响机理。通过热力学和动力学分析研究了温度对反应过程的影响。从热力学分析来看，有水和无水的FeS2（1 0 0）表面的氧化砷生成随温度的升高而减弱。此外，加入H2O的反应的平衡常数略高于不加入H2O的反应的平衡常数，这表明有H2O存在时，化学反应的程度应该会增加。从动力学分析来看，反应速率常数随温度升高而增大，有水和无水氧化砷生成反应的活化能分别为100.72 kJ/mol和124.08 kJ/mol。这表明水在表面的吸附可以降低能垒，加速氧化砷的生成。热力学和动力学分析表明，温度对反应平衡有抑制作用，对反应速率有正向影响。实验和计算结果解释了水对氧化砷形成机理的影响，为砷的排放和控制提供了理论依据。
The effect of H2O on arsenic release behavior was investigated via experiment and first-principles density functional theory (DFT). The experimental results show that sulfide-bound arsenic is the main form present in coal, and that H2O has a positive influence on the release of arsenic during coal combustion. Furthermore, DFT calculations were performed to investigate the mechanism for H2O influence on arsenic oxidation. Thermodynamic and kinetic analyses were also conducted to study the influence of temperature on the reaction process. From thermodynamic analysis, arsenic oxide formation on the FeS2(1 0 0) surface with and without H2O weakens with increasing temperature. In addition, the equilibrium constant for the reaction with H2O addition is slightly higher than that for the reaction without H2O, which suggests that the degree of the chemical reaction in the presence of H2O should increase. From kinetic analysis, the reaction rate constants increase with temperature, and the activation energy of the arsenic oxide formation reaction with and without H2O is 100.72 kJ/mol and 124.08 kJ/mol, respectively. This indicates that H2O adsorption on the surface can decrease the energy barrier and accelerate the reaction forming arsenic oxide. Based on the thermodynamic and kinetic analyses, it can be concluded that temperature has an inhibitory influence on reaction equilibrium and positive influence on the reaction rate. The experiment and calculation results explain the influence of H2O on the formation mechanism of arsenic oxide and provide a theoretical foundation for the emission and control of arsenic.