Effects of molecular weight-dependent physicochemical heterogeneity of natural organic matter on the aggregation of fullerene nanoparticles in mono- and di-valent electrolyte solutions. (15th March 2015)

• Record Type: Journal Article
• Authors: Shen, Mo-Hai; Yin, Yong-Guang; Booth, Andy; Liu, Jing-Fu
• Is Part Of: Water research. Volume 71(2015)
• Page Start: 11
• Page End: 20
• Publication Date: 2015-03-15
• Subjects: Natural organic matter (NOM) -- Molecular weight (MW) -- Fullerene nanoparticles (nC60) -- Aggregation -- Electrolytes; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2014.12.025
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Given the wide presence of heterogeneous natural organic matter (NOM) and metal ions (Na + /Ca 2+ /Mg 2+ ), as well as their significant role in governing nanoparticle stability in aqueous environments, it is of great importance to understand how the molecular weight (MW)-dependent physicochemical properties of NOM impact fundamental transportation processes like the aggregation of engineered nanoparticles (ENPs) in the presence of Na + /Ca 2+ /Mg 2+ . Here, we report on the aggregation behavior of a model ENP, fullerene nanoparticles (nC60 ) in the presence of five MW fractions of Suwannee River NOM (Mf -SRNOMs, separated by ultrafiltration techniques) and three electrolytes (NaCl, CaCl2 and MgCl2 ). We found that in all NaCl treatments and low concentration CaCl2 /MgCl2 treatments, the enhancement of nC60 stability positively correlated with the MW of Mf -SRNOMs. Whereas, the stability efficiency of identical Mf -SRNOM in different electrolytes followed an order of NaCl > MgCl2 > CaCl2, and the enhanced attachment of nC60 -SRNOM associations was observed in high MW Mf -SRNOM (SRNOM>100 kD and SRNOM 30–100 kD) at high concentration CaCl2 /MgCl2 . Our results indicate that although the high MW NOM with large humic-like material is the key component for stabilizing nC60 in monovalent electrolyte, it could play a reversed role in promoting the attachment of nC60, especially in long term aggregations and at high concentrations of divalent cations. Therefore, a detailed understanding of the effects of heterogeneous NOM on the aggregation of ENPs should be highly valued, and properly assessed against different cation species and concentrations. Graphical abstract: Highlights: Enhancement of nC60 stability positively correlates with the MW of NOM in NaCl. nC60 stability in NOM is electrolyte dependent and follows NaCl > MgCl2 > CaCl2 . High MW NOMs stabilize nC60 in NaCl more effectively than low MW counterparts. High MW NOMs promote nC60 attachment and thus aggregation in divalent cations.