Zhang Jia, Yin Huilin, Samuel Barnie, Liu Fei, Chen Honghan
Beijing Key Laboratory of Water Resources & Environmental Engineering, China University of Geosciences Beijing 100083 China
RSC Adv. 2018 Jan 19;8(7):3522-3529. doi: 10.1039/c7ra12146f. eCollection 2018 Jan 16.
Two-dimensional hetero-spectral correlation analysis has been widely used for the interpretation of spectral changes of humic substances involved in various environmental processes. However, when three different types of spectroscopies are utilised, only a pairwise correlation can be achieved. In order to overcome this problem, a novel method of three-dimensional hetero-spectral correlation analysis with scaling technique was developed in this study, which can further establish a direct correlation between three different types of spectroscopies, including FTIR, C CP/MAS NMR, and XPS. The proposed method was applied to the fingerprint identification of undissolved humic acid functional groups for Cr(vi) retention, which is one of the most important points for understanding the migration and transformation of Cr(vi) in a subsurface environment. The results indicated that mainly free and dissociated carboxylic groups, phenolic groups, and polysaccharide participated in the reaction with Cr(vi), and these functional groups were mainly located at aromatic domains. Besides, the variations of functional groups were related to the reduction of Cr(vi), and the reduced Cr(iii) mainly bound to aromatic domains. The successful application of the proposed method demonstrated that it can serve as a promising tool for further investigations concerning more complicated environmental processes and even other scientific fields by supplying more detailed, reliable and visualised spectral information.
二维异谱相关分析已被广泛用于解释参与各种环境过程的腐殖质的光谱变化。然而，当使用三种不同类型的光谱学方法时，只能实现成对相关。为了克服这个问题，本研究开发了一种带有缩放技术的三维异谱相关分析新方法，该方法可以进一步在包括傅里叶变换红外光谱（FTIR）、交叉极化/魔角旋转核磁共振光谱（C CP/MAS NMR）和X射线光电子能谱（XPS）在内的三种不同类型光谱学方法之间建立直接相关性。所提出的方法被应用于未溶解腐殖酸官能团对六价铬保留的指纹识别，这是理解六价铬在地下环境中迁移和转化的最重要要点之一。结果表明，主要是游离和离解的羧基、酚羟基和多糖参与了与六价铬的反应，并且这些官能团主要位于芳香域。此外，官能团的变化与六价铬的还原有关，还原后的三价铬主要与芳香域结合。所提出方法的成功应用表明，通过提供更详细、可靠和可视化的光谱信息，它可以作为一种有前途的工具，用于进一步研究更复杂的环境过程甚至其他科学领域。
