Small-Angle Neutron Scattering Study of Natural Aquatic Nanocolloids

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• 作者：Helen P. Jarvie ; Stephen M. King
• 刊名：Environmental Science & Technology
• 出版年：2007
• 出版时间：April 15, 2007
• 年：2007
• 卷：41
• 期：8
• 页码：2868 - 2873
• 全文大小：140K
• 年卷期：v.41,no.8(April 15, 2007)
• ISSN：1520-5851

文摘

We examine the potential of small-angle neutron scattering(SANS) as a quantitative tool for studying nanostructureand length scales in natural freshwater aquatic colloidaldispersions (river water, river bed sediments, agriculturalfield drainage and slurry). Our results show that naturalaquatic colloids are generally fractal with 3D network-typestructures. None of these structures are consistent withdiffusion-limited (DLCA) or reaction-limited (RLCA) particle-particle aggregation processes. The results also suggestthree characteristic length scales: one ca. 3-10 nm, whichwe identify with "primary particle" sizes, another of ca. 20-50 nm suggestive of small aggregates, and the last ca. 50-200 nm which we postulate arises from transient networksof the aggregates. The role of organic matter in mediatingcolloid structure in aquatic dispersions was examinedby neutron contrast variation and by measuring samplesboth before and after treatment with hydrogen peroxide. Theresults suggest that the aggregate network structure ismediated by organic matter.