In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performa...In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were Hg Cl2,Hg S and Hg O. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor,existed in two forms, Hg Br2 and Hg O, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of Hg Br2 and Hg O in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.展开更多
Flue gas from coal combustion contains significant amounts of volatile selenium （Se）. The capture of Se in the flue gas desulfurization （FGD） scrubber unit has resulted in a generation of metal-laden residues. It ...Flue gas from coal combustion contains significant amounts of volatile selenium （Se）. The capture of Se in the flue gas desulfurization （FGD） scrubber unit has resulted in a generation of metal-laden residues. It is important to determine Se speciation to understand the environmental impact of its disposal. A simple method has been developed for selective inorganic Se（IV）, Se（VI） and organic Se determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry （AFS）. It has been determined that Se（IV）, Se（VI） and organic Se can be accurately determined with detection limits （DL） of 0.05, 0.06 and 0.06 μg/L, respectively. The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by analyzing spiked tap-water samples. Analysis indicates that the concentration of Se is high in FGD liquid residues and primarily exists in a reduced state as selenite （Se（IV））. The toxicity of Se（IV） is the strongest of all Se species. Flue gas desulfurization residues pose a serious environmental risk.展开更多
基金Financial support from the National High Technology Research and Development Program of China (No. 2013AA065404)Program of Introducing Talents of Discipline to Universities of China (111 Project, B12034)Fundamental Research Funds for the Central Universities (13ZD04) is gratefully acknowledged
文摘In this study, the mercury adsorption characteristics of HBr-modified fly ash in an entrained-flow reactor were investigated through thermal decomposition methods. The results show that the mercury adsorption performance of the HBr-modified fly ash was enhanced significantly. The mercury species adsorbed by unmodified fly ash were Hg Cl2,Hg S and Hg O. The mercury adsorbed by HBr-modified fly ash, in the entrained-flow reactor,existed in two forms, Hg Br2 and Hg O, and the HBr was the dominant factor promoting oxidation of elemental mercury in the entrained-flow reactor. In the current study, the concentration of Hg Br2 and Hg O in ash from the fine ash vessel was 4.6 times greater than for ash from the coarse ash vessel. The fine ash had better mercury adsorption performance than coarse ash, which is most likely due to the higher specific surface area and longer residence time.
基金supported by the National Natural Science Foundation of China (No.90410018)the Shanxi Nature Science Foundation (No.20051017)+1 种基金the Shanxi Returned Scholar Research Project (No.2005-21)the Programfor Changjiang Scholars and Innovative Research Team at University in MOE,China (No.IRT0517)
文摘Flue gas from coal combustion contains significant amounts of volatile selenium （Se）. The capture of Se in the flue gas desulfurization （FGD） scrubber unit has resulted in a generation of metal-laden residues. It is important to determine Se speciation to understand the environmental impact of its disposal. A simple method has been developed for selective inorganic Se（IV）, Se（VI） and organic Se determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry （AFS）. It has been determined that Se（IV）, Se（VI） and organic Se can be accurately determined with detection limits （DL） of 0.05, 0.06 and 0.06 μg/L, respectively. The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by analyzing spiked tap-water samples. Analysis indicates that the concentration of Se is high in FGD liquid residues and primarily exists in a reduced state as selenite （Se（IV））. The toxicity of Se（IV） is the strongest of all Se species. Flue gas desulfurization residues pose a serious environmental risk.
