| Aggregation and disaggregation of iron oxide nanoparticles: Influence of particle concentration, pH and natural organic matter. | |
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MedLine Citation:
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PMID: 19059631 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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The surface coating, aggregation behavior and aggregate structure of unpurified iron oxide nanoparticles (NPs) at variable pH and in the absence and presence of natural organic matter (NOM, Suwannee River humic acid, SRHA) have been previously studied in Baalousha et al. [Baalousha, M., Manciulea, A., Cumberland, S., Kendall, K., Lead, J.R., Aggregation and surface properties of iron oxide nanoparticles; influence of pH and natural organic matter. Environ Toxicol Chem 2008; 27: 1875-1882.]. Here the aggregation behavior of iron oxide NPs at variable concentrations of NPs and SRHA, and the disaggregation behavior of iron oxide NP aggregates in the absence and presence of SRHA are investigated. The increase of NP concentration enhances their aggregation, particularly at pH values close to the point of zero charge (PZC). High concentration of SRHA (100 mg l(-1)) shifts the NP (100 mg l(-1)) PZC charge and aggregation maximum towards lower pHs, while low concentration (10 mg l(-1)) shows low or no effect. The disaggregation behavior of iron oxide NP aggregates was investigated at pH 7 and at increasing concentrations of SRHA. High concentrations (50 and 100 mg l(-1)) of SRHA induced the disaggregation of iron oxide NP aggregates with time, which was not the case at lower concentrations (10 mg l(-1)) or in the absence of SRHA. The disaggregation was triggered by the enhanced surface charge induced by the sorption of SRHA molecules. The disaggregation rate increased with SRHA concentration and decreased with time. Two regimes of disaggregation were identified, a fast regime of "fragmentation" at the first 15 days of the experiment and a slow regime of "erosion" afterwards. The formation of small aggregates of about 170 nm and surface coating of several nanometers of SRHA on iron oxide NPs confirm the role of NOM in the disaggregation process and indicate that NPs might mimic the behavior of natural colloids. |
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Authors:
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Mohammed Baalousha |
Publication Detail:
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Type: Journal Article Date: 2008-12-06 |
Journal Detail:
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Title: The Science of the total environment Volume: 407 ISSN: 0048-9697 ISO Abbreviation: Sci. Total Environ. Publication Date: 2009 Mar |
Date Detail:
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Created Date: 2009-02-23 Completed Date: 2009-05-07 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0330500 Medline TA: Sci Total Environ Country: Netherlands |
Other Details:
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Languages: eng Pagination: 2093-101 Citation Subset: - |
Affiliation:
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School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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