| Summary: | 碩士 === 國立臺北科技大學 === 環境工程與管理研究所 === 99 === A Highly porous activated carbon fiber mat (ACM) impregated with various amounts of copper chloride (CuCl2) was examined for its feasibility to remove low-concentration Hg0 from N2 and simulated coal-combustion flue gases. Effects of acid pretreatmenton on carbon’s properties and Hg adsorption capacities were also evaluated. Instrumental analyses including scanning electron microscopy (SEM), surface area analyzer (BET), elements analyzer (EA) and electron spectroscopy for chemical analysis (XPS) were used to explore the influences of surface treatments on physical and chemical characteristics and the Hg0 adsorption performance of the resulting adsorbents.
The experimental results showed that the decrease in surface area and pore volume of ACM was significantly influenced by the amount of impregnated copper, indicating CuCl2 molecules blocking or filling the pore structure of activated carbon. In a simulated flue gas environment, ACM without copper impregnation (designated ACM-raw) had aadsorption capacity of 211.9 ug g-1. HCl pretreatment increased the adsorption capacity of raw ACM (designated HACM-raw) to 512.1 ug g-1. These results suggested that acid pretreatment enhanced the Hg0 adsorption equilibrium of ACM. Furthermore, in N2 environment, the Hg0 adsorption of Cu-impregnated ACM was significantly improved, especially when the Cu impregnation ratio was > 8 wt%. The experimemtal results also showed that the Hg0 adsorption capacity was inversely proportional to the surface area and pore volume of resulting adsorbents. However, Cu impregnation had less effects on enhancing the Hg0 adsorption of ACM under simulated flue gas condition and the adsorption capacities were similar to those obtained from N2 adsorption tests, suggesting that flue gas components may strongly compete the active sites on ACM for Hg0 adsorption, or poison the carbon surface and lead to smaller adsorption capacity. Kinetics analysis results indicated that Hg0 adsorption onto the carbon surface was bimolecular, namely, two active sites were needed for capture of one Hg0 molecules.
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