Facet-Dependent Adsorption and Fractionation of Natural Organic Matter on Crystalline Metal Oxide Nanoparticles
- 21 July 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 54 (14), 8622-8631
- https://doi.org/10.1021/acs.est.9b06111
Abstract
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 (alpha-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.Funding Information
- Ministry of Education of the People's Republic of China (T2017002)
- National Natural Science Foundation of China (21425729, 21976095)
- National Key Research and Development Program of China (2018YFC1800705, 2019YFC1804400)
This publication has 69 references indexed in Scilit:
- Natural, incidental, and engineered nanomaterials and their impacts on the Earth systemScience, 2019
- Environmental processes and toxicity of metallic nanoparticles in aquatic systems as affected by natural organic matterEnvironmental Science: Nano, 2016
- Natural inorganic nanoparticles – formation, fate, and toxicity in the environmentChemical Society Reviews, 2015
- Basin-scale transport of hydrothermal dissolved metals across the South Pacific OceanNature, 2015
- Interactions of Dissolved Organic Matter with Natural and Engineered Inorganic Colloids: A ReviewEnvironmental Science & Technology, 2014
- Comprehensive probabilistic modelling of environmental emissions of engineered nanomaterialsEnvironmental Pollution, 2014
- Preservation of organic matter in sediments promoted by ironNature, 2012
- Estimates of Upper Bounds and Trends in Nano-TiO2 Production As a Basis for Exposure AssessmentEnvironmental Science & Technology, 2009
- Nanominerals, Mineral Nanoparticles, and Earth SystemsScience, 2008
- Nanomaterials and nanoparticles: Sources and toxicityBiointerphases, 2007