Department of Environment and Energy, Sejong University, Seoul 143-747, South Korea.
Chemosphere. 2013 Jan;90(2):237-44. doi: 10.1016/j.chemosphere.2012.06.060. Epub 2012 Jul 24.
The characteristics of extracellular polymeric substances (EPSs) were compared for two different extraction methods and dissimilar sludge formation conditions (aerobic versus anaerobic). The measured characteristics included specific ultraviolet absorbance (SUVA) values, fluorescence excitation-emission matrices, molecular weight distributions, Fourier transform infrared (FT-IR) spectra, and the binding affinities for pyrene and Hg(II). The analyses demonstrated that the EPS extracted using cation exchange resin (CER) were composed of more aromatic and more condensed structures with higher molecular weight than those using formaldehyde/NaOH. The FT-IR results further revealed that the EPS using CER contained relatively lower content of protein to carbohydrate and less acidic functional groups (i.e., COOH or OH groups). The observed differences between the two extraction methods were more pronounced for the EPS of anaerobic sludge compared to those of aerobic sludge. The extent of pyrene binding and the apparent stability constants for Hg(II) were very consistent with the implications from the previous EPS physicochemical characteristics. The highest extent of pyrene binding was observed for the EPS of anaerobic sludge using CER while no measurable Hg(II) stability constant was found for the same EPS sample. Our results demonstrated that the EPS characteristics including their binding affinities are likely strongly affected by the sludge formation conditions as well as the extraction methods although the latter produced more differences.
比较了两种不同提取方法和不同污泥形成条件（好氧与厌氧）下胞外聚合物（EPS）的特性。测量的特性包括比紫外吸收值（SUVA）、荧光激发-发射矩阵、分子量分布、傅里叶变换红外（FT-IR）光谱以及对芘和 Hg(II)的结合亲和力。分析表明，与使用甲醛/NaOH 的方法相比，使用阳离子交换树脂（CER）提取的 EPS 具有更多的芳香性和更密集的结构，分子量更高。FT-IR 结果进一步表明，使用 CER 提取的 EPS 含有相对较低含量的蛋白质与碳水化合物，以及较少的酸性官能团（即 COOH 或 OH 基团）。与好氧污泥相比，两种提取方法之间的差异在厌氧污泥的 EPS 中更为明显。芘结合的程度和 Hg(II)的表观稳定常数与之前 EPS 物理化学特性的含义非常一致。使用 CER 提取的厌氧污泥的 EPS 表现出最大的芘结合程度，而对于相同的 EPS 样品，没有发现可测量的 Hg(II)稳定常数。我们的结果表明，尽管后者产生了更多差异，但 EPS 的特性，包括其结合亲和力，可能受到污泥形成条件以及提取方法的强烈影响。
