为了探讨污泥堆肥过程中亲水性组分(hydrophilic fraction,HyI)的结构组成和电子转移能力的变化规律和机理,本研究以污泥堆肥过程中的HyI为研究对象,采用紫外-可见光谱(UV-Vis)、三维荧光光谱(3D-EEM)、傅里叶变换红外光谱(FTIR)、二维相关光谱(2D-COS)和电化学方法,对其结构组成和电子转移能力的变化进行了系统研究.光谱分析显示,随着堆肥的进行,HyI中芳香族化合物含量增加,醌基含量增加,类蛋白物质含量降低,类胡敏酸物质和类富里酸物质含量增加,芳构化程度和腐殖化程度增强.酰胺和多糖类物质在HyI中占据主导地位,HyI中的羧基含量增加,而酚类含量降低.电化学分析显示,在堆肥过程中,HyI的电子供给能力(electron donating capacity,EDC)呈现先增加后减少的趋势;HyI的电子接受能力(electron accepting capacity,EAC)呈现先减少后增加的趋势.总体上,HyI的电子转移能力(electron transfer capacities,ETC)呈现上升的趋势,表明堆肥过程提高了HyI的氧化还原能力.相关性分析显示,HyI分子量越小、硅酸盐和多糖含量越低,越利于HyI给出电子;而HyI羧基含量越高、类胡敏酸物质越多、腐殖化程度越高、芳香性越强,越利于HyI得到电子.研究显示,污泥堆肥过程中HyI的结构组成和电子转移能力发生了显著变化,HyI分子量的降低、功能基团硅酸盐含量的降低和腐殖化程度的升高与HyI的电子转移能力有密切关系.该结果有助于进一步了解污泥堆肥过程中HyI的形成及其氧化还原特性,为发挥其在治理环境污染中的作用提供依据.
In order to explore the change rules and mechanisms of the structural composition and electron transfer capacity of the hydrophilic fraction(HyI)during sludge composting,the HyI was investigated in this study using various analytical techniques,including ultraviolet-visible spectroscopy,excitation-emission matrix spectroscopy,Fourier-transform infrared spectroscopy,two-dimensional correlation spectroscopy,and electrochemical methods.The spectral analysis revealed that during composting process,the contents of aromatic compounds,quinone groups,humic-and fulvic-like substances,as well as aromatization and humification increased in HyI and the content of proteinoid substances decreased.HyI predominantly contained amides and polysaccharides.The content of the carboxyl group in HyI increased,while the content of phenols decreased.Electrochemical analysis showed that the electron-donating capacity of HyI initially increased and subsequently decreased during composting process.The electron acceptance capacity first decreased and then increased.Overall,the electron transfer capacities of HyI gradually increased,indicating that the redox capacity of HyI increased during composting process.Correlation analysis indicated that the smaller the molecular weight of HyI and the lower the contents of silicate and polysaccharide,the stronger the electron-donating capacity of HyI.Additionally,higher carboxyl group content,more humic substances,higher humification,and higher aromaticity were beneficial to the electron acquisition of HyI.The results showed that the structural composition and electron transfer capacity of HyI changed significantly during sludge composting process.The decrease in HyI molecular weight,the decrease in functional group silicate content,and the increase in humification degree were closely related to the electron transfer capacity of HyI.These findings contribute to our understanding of the formation and redox properties of HyI during sludge composting process and provide insights into its role in environmental pollution control.