| 水钠锰矿的锰氧化度与Pb2+吸附量的关系 |
| 摘要点击 2471 全文点击 1624 投稿时间：2008-02-20 修订日期：2008-03-29 |
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| 中文关键词 Pb2+ 吸附 水钠锰矿 锰氧化度 八面体空穴 |
| 英文关键词 Pb2+ adsorption birnessite Mn average oxidation state vacant site |
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| 中文摘要 |
| 研究水钠锰矿对重金属离子的吸附，其结构中八面体空穴特点与重金属离子吸附的关系是人们关注的热点.采用酸性和碱性2种介质条件合成了具有不同锰氧化度的2个系列水钠锰矿，研究了它们的锰氧化度(average oxidation state of Mn, AOS)与其d110面网间距和Pb2+的最大吸附量的关系，以及Pb2+吸附量与Mn2+、H+和K+释放量的关系.结果表明，同系列的水钠锰矿具有相似的晶体形貌，它们的锰氧化度与其d110面网间距呈极显著的负相关(r =-0.903 5<-0.661 4，n=14，α=0.01)，而与Pb2+的最大吸附量呈极显著的正相关(r=0.977 9>0.661 4，n=14，α=0.01)，供试水钠锰矿锰氧化度的高低表观上反映了结构中八面体空穴数量的多少，水钠锰矿随着锰氧化度的提高，导致其结构中的八面体空穴数增多，对Pb2+的吸附容量增大，八面体空穴数量对Pb2+的吸附量的大小起着非常重要的作用.Pb2+的吸附量与吸附过程中Mn2+、H+和K+的释放量之和呈极显著的正相关(r = 0.996 2 > 0.661 4，n = 14，α = 0.01)，Pb2+吸附过程中伴随的Mn2+、H+和K+的释放主要来自于水钠锰矿结构中八面体空穴处吸附的相应阳离子.吸附前Mn2+,Mn3+与H+、K+占据水钠锰矿结构中八面体空穴上下方位点的相对多少受水钠锰矿的锰氧化度高低的影响，锰氧化度低时，八面体空穴上下方位点吸附Mn2+、Mn3+较多，吸附的H+、K+则较少，反之亦然. |
| 英文摘要 |
| Vacant sites in Mn oxides, commonly occur in soils, play an important role in their heavy metal adsorption behavior. The dependence of Pb2+ adsorption capacity for the synthesized birnessites and their d110-interplanar spacing on the respective Mn average oxidation state (AOS), and the relationship between Pb2+ adsorption and the Mn2+, H+, K+ released during adsorption were investigated. The results show that Mn AOS of birnessites apparently reflects their amount of vacant sites which largely account for the Pb2+ adsorption. Significant positive correlation between Pb2+ adsorption capacity and the Mn AOS of corresponding birnessites(r=0.977 9 >0.661 4, n = 14, α = 0.01), negative correlation between d110 spacing and the Mn AOS(r =-0.903 5 < -0.661 4，n = 14，α = 0.01), and significant positive correlation between Pb2+ adsorption and the Mn2+, H+, K+ released during adsorption(r= 0.996 2 > 0.661 4，n = 14，α = 0.01) are found. The vacant sites amount increases with Mn AOS for birnessites, which causes the increase of Pb2+ adsorption. Therefore, the Pb2+ adsorption capacity of birnessite is largely determined by the amount of vacant sites, from which Mn2+, H+, and K+ released during adsorption are mostly derived. |
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