Department of Chemistry, University of Science and Technology of China , Hefei, Anhui 230026, China.
Environ Sci Technol. 2014 Oct 7;48(19):11119-26. doi: 10.1021/es502502n. Epub 2014 Sep 26.
The elucidation of the interaction between TiO2 nanoparticles (NPs) and natural organic matter (NOM) can help one to better understand the fates, features, and environmental impacts of NPs. In this work, two-dimensional (2D) Fourier transformation infrared (FTIR) correlation spectroscopy (CoS) assisted by the fluorescence excitation-emission matrix (EEM) method is used to explore the interaction mechanism of humic acid (HA) with TiO2 NPs at a molecular level. The results show that the C═O bonds (carboxylate, amide, quinone, or ketone) and C-O bonds (phenol, aliphatic C-OH, and polysaccharide) of HA play important roles in their interaction with TiO2 NPs. The adsorption process of HA onto the surface of TiO2 NPs is different from the bonding process of the two species in solution. The forms of the relevant groups of HA and their consequent reaction with TiO2 NPs are affected to a great extent by the solution pH and the surface charge of NPs. The 2D-FTIR-CoS method is found to be able to construct a comprehensive picture about the NOM-TiO2 NPs interaction process. This 2D-FTIR-CoS approach might also be used to probe other complicated interaction processes in natural and engineered environments.
阐明 TiO2 纳米颗粒（NPs）与天然有机物（NOM）之间的相互作用可以帮助人们更好地了解 NPs 的命运、特征和环境影响。在这项工作中，二维（2D）傅里叶变换红外（FTIR）相关光谱（CoS）结合荧光激发-发射矩阵（EEM）方法用于在分子水平上探索腐殖酸（HA）与 TiO2 NPs 的相互作用机制。结果表明，HA 中的 C═O 键（羧酸盐、酰胺、醌或酮）和 C-O 键（酚、脂肪族 C-OH 和多糖）在其与 TiO2 NPs 的相互作用中起着重要作用。HA 吸附到 TiO2 NPs 表面的过程不同于两种物质在溶液中的键合过程。相关 HA 基团的形式及其与 TiO2 NPs 的后续反应在很大程度上受到溶液 pH 值和 NPs 表面电荷的影响。发现 2D-FTIR-CoS 方法能够构建 NOM-TiO2 NPs 相互作用过程的综合图像。这种 2D-FTIR-CoS 方法也可用于探测自然和工程环境中其他复杂的相互作用过程。
