Sorption of Strontium onto Bacteriogenic Iron Oxides
Sorption of Strontium onto Bacteriogenic Iron Oxides
复制标题
DOI：
10.1021/es802027f
复制
发表时间：
2009-02-15
影响因子：
11.4
通讯作者：
Ferris, F. Grant
中科院分区：
文献类型：
--
作者：
Langley, Sean;Gault, Andrew G.;Ferris, F. Grant
细菌氧化铁（BIOS）从一个稀释的，环中性地下水渗漏，其特征在于相对于矿物学，并检查其吸附水Sr 2+的能力。BIOS是由微生物鞘包被在2线的水铁矿中组成的。吸附实验表明，Sr在pH < 4.5时保持完全未结合，但吸附随pH增加而增加（在pH > 7.6时最大为95%）。锶加载BIOS的EXAFS分析未能阐明是否Sr吸附发生在特定的矿物或微生物馏分的网站上，但表明吸附可能发生的BIOS和水合Sr 2+之间的外层络合。吸附实验表明，在低离子强度（I=0.001 M），吸附遵循Langmuir等温线（S-max = 3.41 mol Sr（g of Fe）（1-），K-ads = 1.26）。在较高的离子强度（I=0.1 M），有显着的抑制Sr的吸附（S-max = 1.06摩尔Sr（g的Fe）（1-），K-ads = 1.23），这表明吸附BIOS发生外层络合。结果表明，在稀释的环中性条件下，BIOS存款应有效地吸附溶解Sr从地下水流系统中存在这样的存款。这一发现对受放射性Sr-90地下水污染影响的地点特别重要。
Bacteriogenic iron oxides (BIOS) were obtained from a dilute, circumneutral groundwater seep, characterized with respect to mineralogy, and examined for their ability to sorb aqueous Sr2+. BIOS were composed of microbial sheaths encrusted in 2-line ferrihydrite. Sorption experiments indicated that Sr remained completely unbound at pH < 4.5, but sorption increased with increasing pH (maximum of 95% at pH > 7.6). EXAFS analysis of Sr-loaded BIOS failed to elucidate whether Sr sorption occurred on sites specific to the mineral or microbial fraction, but indicated that sorption likely occurred by outer-sphere complexation between BIOS and hydrated Sr2+. Sorption experiments showed that, at low ionic strength (I=0.001 M), sorption followed a Langmuir isotherm (S-max = 3.41 mol Sr (g of Fe)(1-), K-ads = 1.26). At higher ionic strength (I=0.1 M), there was significant inhibition of Sr sorption (S-max = 1.06 mol Sr (g of Fe)(1-), K-ads = 1.23), suggesting that sorption to BIOS occurs by outer-sphere complexation. The results suggest that, under dilute circumneutral conditions, BIOS deposits should efficiently sorb dissolved Sr from groundwater flow systems where such deposits exist. This finding has particular relevance to sites impacted by radioactive Sr-90 groundwater contamination.