活性炭用于从水中吸附有机微污染物(OMPs),通常以ngL-1至μgL-1的浓度存在。然而,由于来自背景溶解有机物(DOM)的竞争性吸附,OMP去除的功效大大恶化,以mgL-1表示的浓度高得多。解释竞争性DOM的特征对于预测不同自然水域的OMP吸附效率至关重要。分子量(MW),芳香性,极性影响DOM竞争力。尽管与芳香性相关的指标,如UV254,低MWDOM被提出与DOM竞争力相关,该方法在理解确定DOM竞争力时极性和芳香性的相互作用方面存在局限性。这里,我们阐明了芳香性和极性在低MWDOM竞争中的复杂影响,从分数级别到复合级别,采用直接进样液相色谱与超高分辨率傅里叶变换离子回旋共振质谱联用。阴离子交换树脂预处理消除了93%的UV254活性DOM,主要是芳香和极性DOM,并且只能最低限度地缓解DOM竞争。分子表征表明,具有中等芳香性的非极性分子式(占26%的PAC可吸附DOM)对DOM竞争力的贡献更大。异构体水平分析表明,高度芳香族LMWDOM化合物的竞争力被极性的增加强烈抵消。强烈的芳香性衍生的π-π相互作用不能促进亲水性DOM化合物的竞争吸附。我们的结果强调了仅依赖基于芳香性的方法作为DOM竞争力的独家解释性度量的局限性。在更广泛的背景下,这项研究展示了一种面向效果的DOM分析,阐明DOM分子性质从分数到化合物水平的平衡相互作用。
Activated carbon is employed for the adsorption of organic micropollutants (OMPs) from water, typically present in concentrations ranging from ng L-1 to μg L-1. However, the efficacy of OMP removal is considerably deteriorated due to competitive adsorption from background dissolved organic matter (DOM), present at substantially higher concentrations in mg L-1. Interpreting the characteristics of competitive DOM is crucial in predicting OMP adsorption efficiencies across diverse natural waters. Molecular weight (MW), aromaticity, and polarity influence DOM competitiveness. Although the aromaticity-related metrics, such as UV254, of low MW DOM were proposed to correlate with DOM competitiveness, the method suffers from limitations in understanding the interplay of polarity and aromaticity in determining DOM competitiveness. Here, we elucidate the intricate influence of aromaticity and polarity in low MW DOM competition, spanning from a fraction level to a compound level, by employing direct sample injection liquid chromatography coupled with ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry. Anion exchange resin pre-treatment eliminated 93% of UV254-active DOM, predominantly aromatic and polar DOM, and only minimally alleviated DOM competition. Molecular characterization revealed that nonpolar molecular formulas (constituting 26% PAC-adsorbable DOM) with medium aromaticity contributed more to the DOM competitiveness. Isomer-level analysis indicated that the competitiveness of highly aromatic LMW DOM compounds was strongly counterbalanced by increased polarity. Strong aromaticity-derived π-π interaction cannot facilitate the competitive adsorption of hydrophilic DOM compounds. Our results underscore the constraints of depending solely on aromaticity-based approaches as the exclusive interpretive measure for DOM competitiveness. In a broader context, this study demonstrates an effect-oriented DOM analysis, elucidating counterbalancing interactions of DOM molecular properties from fraction to compound level.