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Structure and properties of Co-doped cryptomelane and its enhanced removal of Pb^(2+) and Cr^(3+) from wastewater
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作者 Hui Li Fan Liu +3 位作者 mengqiang zhu Xionghan Feng Jing Zhang Hui Yin 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2015年第8期77-85,共9页
Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, s... Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectroscopy, and its performances for removal of Pb^2+ and Cr^3+ from aqueous solutions were investigated. Co doping has a negligible effect on the structure and morphology of cryptomelane but increases the specific surface area and Mn average oxidation state. Mn and Co K-edge extended X-ray absorption fine structure spectroscopy(EXAFS) analysis shows that Co barely affects the atomic coordination environments of Mn, and distances of edge- and corner-sharing Co–Me(Me_Co, Mn) pairs are shorter than those of the corresponding Mn–Me pairs, implying the replacement of framework Mn(III) by Co(III). These Co-doped cryptomelanes can quickly oxidize Cr3+to be HCr O4-and remove 45%–66% of the total Cr in the reaction systems by adsorption and fixation, and they have enhanced Pb2+adsorption capacities. Thus these materials are promising adsorbents for heavy metal remediation. The results demonstrate the design and modification of environmental friendly Mn oxide materials and can help us understand the interaction mechanisms of transition metals with Mn oxides. 展开更多
关键词 Cryptomelane Co doping EXAFS Pb2+adsorption Cr^3+oxidation
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