Mining activities have created great wealth, but they have also discharged large quantities of tailings. As an important source of heavy metal contamination, sulfide tailings are usually disposed of in open-air impoun...Mining activities have created great wealth, but they have also discharged large quantities of tailings. As an important source of heavy metal contamination, sulfide tailings are usually disposed of in open-air impoundments and thus are exposed to microbial oxidation. Microbial activities greatly enhance sulfide oxidation and result in the release of heavy metals and the precipitation of iron (oxy) hydroxides and sulfates. These secondary minerals in turn influence the mobility of dissolved metals and play important roles in the natural attenuation of heavy metals. Elucidating the microbe–mineral interactions in tailings will improve our understanding of the environmental consequence of mining activities.展开更多
The Ti-modified sepiolite （Ti-Sep）-supported Mn-Cu mixed oxide （yMn5Cu/Ti-Sep） catalysts were synthesized using the co-precipitation method. The materials were characterized by the X-ray diffraction scanning elect...The Ti-modified sepiolite （Ti-Sep）-supported Mn-Cu mixed oxide （yMn5Cu/Ti-Sep） catalysts were synthesized using the co-precipitation method. The materials were characterized by the X-ray diffraction scanning electron microscope, N2 adsorption-desorption, H2-TPR, O2-TPD, and XPS techniques, and their catalytic activities for CO oxidation were evaluated. It was found that the catalytic activities ofyMn5Cu/Ti-Sep were higher than those of 5Cu/Ti-Sep and 30Mn/Ti-Sep, and the Mn/Cu molar ratio had a distinct influence on catalytic activity of the sample. Among the yMn5Cu/Ti- Sep samples, the 30Mn5Cu/Ti-Sep catalyst showed the best activity （which also outperformed the 30Mn5Cu/Sep catalyst）, giving the highest reaction rate of 0.875 × 10^- 3 mmol· g^-1· s^-1 and the lowest T50%and T100% of 56℃ and 86℃, respectively. Moreover, the 30Mn5Cu/Ti-Sep possessed the best low-temperature reducibility, the lowest 02 desorption temperature, and the highest surface Mn3＋/ Mn4＋ atomic ratio. It is concluded that factors, such as the strong interaction between the copper or manganese oxides and the Ti-Sep support, good low-temperature reducibility, and good mobility of ehemisorbed oxygen species, were responsible for the excellent catalytic activity of 30Mn5Cu/Ti-Sep.展开更多
文摘Mining activities have created great wealth, but they have also discharged large quantities of tailings. As an important source of heavy metal contamination, sulfide tailings are usually disposed of in open-air impoundments and thus are exposed to microbial oxidation. Microbial activities greatly enhance sulfide oxidation and result in the release of heavy metals and the precipitation of iron (oxy) hydroxides and sulfates. These secondary minerals in turn influence the mobility of dissolved metals and play important roles in the natural attenuation of heavy metals. Elucidating the microbe–mineral interactions in tailings will improve our understanding of the environmental consequence of mining activities.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant Nos. 21277008 and 20777005） and Natural Science Foundation of Beijing （No. 8082008）.
文摘The Ti-modified sepiolite （Ti-Sep）-supported Mn-Cu mixed oxide （yMn5Cu/Ti-Sep） catalysts were synthesized using the co-precipitation method. The materials were characterized by the X-ray diffraction scanning electron microscope, N2 adsorption-desorption, H2-TPR, O2-TPD, and XPS techniques, and their catalytic activities for CO oxidation were evaluated. It was found that the catalytic activities ofyMn5Cu/Ti-Sep were higher than those of 5Cu/Ti-Sep and 30Mn/Ti-Sep, and the Mn/Cu molar ratio had a distinct influence on catalytic activity of the sample. Among the yMn5Cu/Ti- Sep samples, the 30Mn5Cu/Ti-Sep catalyst showed the best activity （which also outperformed the 30Mn5Cu/Sep catalyst）, giving the highest reaction rate of 0.875 × 10^- 3 mmol· g^-1· s^-1 and the lowest T50%and T100% of 56℃ and 86℃, respectively. Moreover, the 30Mn5Cu/Ti-Sep possessed the best low-temperature reducibility, the lowest 02 desorption temperature, and the highest surface Mn3＋/ Mn4＋ atomic ratio. It is concluded that factors, such as the strong interaction between the copper or manganese oxides and the Ti-Sep support, good low-temperature reducibility, and good mobility of ehemisorbed oxygen species, were responsible for the excellent catalytic activity of 30Mn5Cu/Ti-Sep.
