Characterization of metal-cyanobacteria sorption reactions: a combined macroscopic and infrared spectroscopic investigation.
Characterization of metal-cyanobacteria sorption reactions: a combined macroscopic and infrared spectroscopic investigation.
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DOI：
10.1021/es0346680
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发表时间：
2004-02
影响因子：
11.4
通讯作者：
N. Yee;L. Benning;V. Phoenix;F. Ferris
中科院分区：
文献类型：
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作者：
N. Yee;L. Benning;V. Phoenix;F. Ferris
在这项研究中，我们通过同步辐射傅里叶变换红外光谱、电位滴定和金属吸附实验来表征金属-蓝藻的吸附反应。在溶液中采集完整蓝藻细丝和分离的外聚合鞘材料的红外光谱，以检测细胞表面官能团的去质子化反应。从pH 3.2到6.5依次滴定的完整细胞的红外光谱显示，1400 cm(-1)处的峰强度和面积增加，对应于去质子化的羧基表面位置形成的振动COO频率。同样，蓝藻细丝和鞘材料的整体酸碱滴定表明，与上覆鞘相比，细胞壁上的质子活性表面位置的浓度更高。三位点模型能很好地拟合完整细胞和鞘材料的滴定曲线，相应的pKa值分别为4.7+/-0.4、6.6+/-0.2、9.2+/-0.3和4.8+/-0.3、6.5+/-0.1、8.7+/-0.2。最后，进行了Cu2+、Cd2+、Pb2+随pH变化的吸附实验，并用特定位置的表面络合模型描述了金属的吸附数据。模拟表明，金属离子在胞外聚合物鞘和细胞壁之间分配，在近中性pH下，蓝藻细胞壁上的羧基是金属的主要汇。这些结果表明，蓝藻表面是复杂的结构，包含不同的表面层，每个表面层都具有独特的分子官能团和金属结合特性。
In this study, we conducted synchrotron radiation Fourier transform infrared (IR) spectroscopy, potentiometric titration, and metal sorption experiments to characterize metal-cyanobacteria sorption reactions. Infrared spectra were collected with samples in solution for intact cyanobacterial filaments and separated exopolymeric sheath material to examine the deprotonation reactions of cell surface functional groups. The infrared spectra of intact cells sequentially titrated from pH 3.2 to 6.5 display an increase in peak intensity and area at 1400 cm(-1) corresponding to vibrational COO- frequencies from the formation of deprotonated carboxyl surface sites. Similarly, bulk acid-base titration of cyanobacterial filaments and sheath material indicates that the concentration of proton-active surface sites is higher on the cell wall compared to the overlying sheath. A three-site model provides an excellent fit to the titration curves of both intact cells and sheath material with corresponding pKa values of 4.7 +/- 0.4, 6.6 +/- 0.2, 9.2 +/- 0.3 and 4.8 +/- 0.3, 6.5 +/- 0.1, 8.7 +/- 0.2, respectively. Finally, Cu2+, Cd2+, and Pb2+ sorption experiments were conducted as a function of pH, and a site-specific surface complexation model was used to describe the metal sorption data. The modeling indicates that metal ions are partitioned between the exopolymer sheath and cell wall and that the carboxyl groups on the cyanobacterial cell wall are the dominant sink for metals at near neutral pH. These results demonstrate that the cyanobacterial surfaces are complex structures which contain distinct surface layers, each with unique molecular functional groups and metal binding properties.