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Facet-Dependent Adsorption and Fractionation of Natural Organic Matter on Crystalline Metal Oxide Nanoparticles.
Environmental Science & Technology ( IF 11.4 ) Pub Date : 2020-06-15 , DOI: 10.1021/acs.est.9b06111
Zelin Shen 1 , Zhanhua Zhang 1 , Tong Li 1 , Qingqian Yao 1 , Tong Zhang 1 , Wei Chen 1
Affiliation  

Natural organic matter (NOM) and crystalline metal oxide nanoparticles are both prevalent in natural aquatic environments, and their interactions have important environmental and biogeochemical implications. Here, we show that these interactions are significantly affected by an intrinsic property of metal oxide nanocrystals, the exposed facets. Both anatase (TiO2) and hematite (α-Fe2O3) nanocrystals, representing common engineered and naturally occurring metal oxides, exhibited apparent facet-dependent adsorption of humic acid and fulvic acid. This facet-dependent binding was primarily driven by surface complexation between the NOM carboxyl groups and surficial metal atoms. Thus, the adsorption affinity of different-faceted nanocrystals was determined by the atomic arrangements of crystal facets that controlled the activity of metal atoms and, consequently, the ligand exchange and binding configuration of the carboxyl groups in the first hydration shell of nanocrystals. Distinct facet-dependent fractionation patterns were observed during adsorption of NOM components, particularly the low-molecular-weight and photorefractory constituents. The molecular fractionation of NOM between water and metal oxide nanoparticles was dictated by the combined effects of facet-dependent metal complexation, hydrophobic interaction, and steric hindrance and may significantly influence the NOM-driven processes occurring both in aqueous phases and at water–nanoparticle interfaces.

中文翻译:

晶体有机氧化物纳米颗粒对天然有机物的刻面依赖性吸附和分离。

天然有机物(NOM)和晶体金属氧化物纳米粒子在天然水生环境中都很普遍,它们之间的相互作用对环境和生物地球化学具有重要意义。在这里,我们表明,这些相互作用受到金属氧化物纳米晶体(暴露面)的固有特性的显着影响。锐钛矿型(的TiO 2)和赤铁矿(α-的Fe 2 ö 3纳米晶体代表了常见的工程金属和天然存在的金属氧化物,表现出腐殖酸和黄腐酸的明显的面相关吸附。这种依赖于面的结合主要是由NOM羧基和表面金属原子之间的表面络合驱动的。因此,不同面的纳米晶体的吸附亲和力由控制金属原子活性的晶面的原子排列以及因此决定的纳米晶体的第一水合壳中的配体交换和羧基的键合构型决定。在吸附NOM组分(尤其是低分子量和耐光组分)的过程中,观察到了不同的分面依赖性分馏模式。
更新日期:2020-07-21
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