Abstract：
Persulfate advanced oxidation technology is widely utilized for remediating organic-contaminated groundwater. Post-remediation by persulfate oxidation, the aromaticity of dissolved organic matter (DOM) in groundwater is significantly reduced. Nevertheless, the evolution trends of aromaticity and related structural changes in DOM remained unclear. Here, we selected eight types of DOM to analyze the variation in aromaticity, molecular weight, and fluorescence characteristics during oxidation by persulfate using optical spectroscopy and parallel faction analysis combined with two-dimensional correlation spectroscopy analysis (2D PARAFAC COS). The results showed diverse trends in the changes of aromaticity and maximum fluorescence intensity (Fmax) among different types of DOM as the reaction time increases. Four types of DOM (humic acid 1S104H, fulvic acid, and natural organic matters) exhibited an initially noteworthy increase in aromaticity followed by a decrease, while others demonstrated a continuous decreasing trend (14.3%-69.4%). The overall decreasing magnitude of DOM aromaticity follows the order of natural organic matters ≈ commercial humic acid > fulvic acid > extracted humic acid. The Fmax of humic acid increased, exception of commercial humic acid. The Fmax of fulvic acid initially decreased and then increased, while that of natural organic matters exhibited a decreasing trend (86.4%). The fulvic acid-like substance is the main controlling factor for the aromaticity and molecular weight of DOM during persulfate oxidation process. The oxidation sequence of fluorophores in DOM is as follows: fulvic-like substance, microbial-derived humic-like substance, humic-like substance, and aquatic humic-like substance. The fulvic-like and microbial-derived humic-like substances at longer excitation wavelengths were more sensitive to the response of persulfate oxidation than that of shorter excitation wavelengths. This result reveals the structure evolution of DOM during persulfate oxidation process and provides further support for predicting its environmental behavior.
摘要：
过硫酸盐高级氧化技术被广泛用于修复有机污染的地下水。过硫酸盐氧化后修复，地下水中溶解有机物（DOM）的芳香性显着降低。然而，DOM芳香性的演变趋势和相关的结构变化尚不清楚。这里,我们选择了八种DOM来分析芳香性的变化，分子量,和荧光特性在过硫酸盐氧化过程中使用光谱和平行比分析结合二维相关光谱分析（2DPARAFACCOS）。结果表明，随着反应时间的增加，不同类型的DOM之间的芳香性和最大荧光强度（Fmax）的变化趋势不同。四种类型的DOM（腐殖酸1S104H，富里酸，和天然有机物)表现出最初值得注意的芳香性增加，然后下降，而其他人则表现出持续下降的趋势（14.3%-69.4%）。DOM芳香性的总体下降幅度遵循天然有机物≈商业腐殖酸>富里酸>提取的腐殖酸的顺序。腐殖酸的Fmax增加，商业腐殖酸的例外。富里酸的Fmax最初降低，然后升高，天然有机物呈下降趋势(86.4%)。黄腐酸类物质是过硫酸盐氧化过程中DOM芳香性和分子量的主要控制因素。DOM中荧光团的氧化顺序如下：黄腐样物质，微生物来源的腐殖质样物质，类腐殖质,和水生腐殖质。与较短激发波长的过硫酸盐氧化反应相比，在较长激发波长下的黄腐状和微生物来源的腐殖质对过硫酸盐氧化反应更敏感。该结果揭示了DOM在过硫酸盐氧化过程中的结构演变，为预测其环境行为提供了进一步的支持。
