Relationship between fluorescence excitation-emission matrix properties and the relative degree of DOM hydrophobicity in wastewater treatment effluents
Relationship between fluorescence excitation-emission matrix properties and the relative degree of DOM hydrophobicity in wastewater treatment effluents
复制标题
废水处理废水中荧光激发-发射基质特性与 DOM 疏水性相对程度之间的关系
DOI：
10.1016/j.chemosphere.2020.126830
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发表时间：
2020
期刊：
影响因子：
8.8
通讯作者：
Huang X.
中科院分区：
文献类型：
--
作者：
Xiao K.;Yu J.;Wang S.;Du J.;Tan J.;Xue K.;Wang Y.;Huang X.
激发-发射矩阵（EEM）荧光光谱是表征废水系统中溶解性有机物（DOM）的有力工具。它是特别有价值的，如果它的效用可以通过连接的光谱特征，疏水性，DOM的基本物理化学性质之一，扩展。在这项研究中，我们采用DAX-8树脂柱来分级DOM的疏水/亲水组分，并通过调整临界保留因子（k 'cr，处理后的水样体积与柱体积的比值）来确定疏水性的相对程度。较高的k 'cr将导致柱流出物的较高疏水性。在不同的k 'cr值下（5、10、25、50、100和200），检查所获得的DOM组分的EEM特性，包括总体特性（平均荧光/总有机碳和紫外吸收），区域特性（荧光区域积分（FRI）及其次级参数）和能量相关性质（激发态的能级、激发态弛豫的斯托克斯位移和荧光寿命）。以污水膜生物反应器和氧化沟为例，大量的EEM特性随logk'cr的变化显著（r> 0.9，p < 0.05）。单位紫外吸收的平均荧光（反映量子产率）、斯托克斯位移≥ 1.1 μm−1时的荧光比例以及一些次要的FRI参数与logk'cr呈现最佳的线性拟合，表明π共轭结构随DOM疏水性相对程度的平滑变化。这可能有助于进一步理解EEM指纹与DOM疏水性之间的关系。
Excitation-emission matrix (EEM) fluorescence spectroscopy is a powerful tool for the characterization of dissolved organic matter (DOM) in wastewater systems. It is of particular value if its utility could be extended by connecting the spectral features to hydrophobicity, one of the fundamental physicochemical properties of DOM. In this study, we employed a DAX-8 resin column to fractionate the hydrophobic/philic components of DOM and determine the relative degree of hydrophobicity by adjusting the critical retention factor (k’cr, the ratio of treated water sample volume to column volume). A higherk’crwould result in a higher hydrophobicity of the column effluent. At differentk’crvalues (5, 10, 25, 50, 100, and 200), the EEM characteristics of the obtained DOM components were inspected, including overall properties (average fluorescence per total organic carbon and UV absorbance), regional properties (fluorescence regional integration (FRI) and its secondary parameters), and energy-related properties (energy level of the excited states, Stokes shift for relaxation of the excited states, and fluorescence lifetime). In case studies of a wastewater membrane bioreactor and an oxidation ditch, plenty of the EEM properties varied significantly with logk’cr(r> 0.9,p< 0.05). The average fluorescence per UV absorbance (reflecting quantum yield), fluorescence proportion at Stokes shift ≥ 1.1 μm−1, and some secondary FRI parameters presented the best linear fitting with logk’cr, suggesting a smooth variation of the π-conjugated structures with the relative degree of DOM hydrophobicity. This may help to further understand the relationship between EEM fingerprints and DOM hydrophobicity.