Impact of natural organic matter and divalent cations on the stability of aqueous nanoparticles.

The stability of nanoparticles in aquatic environment plays an important role in determining their environmental implication and potential risk to human health. This research studied the impact of natural organic matter (NOM) and divalent cations (Ca(2+)) on the stability of engineered metal oxide nanoparticles (e.g. ZnO, NiO, TiO(2), Fe(2)O(3) and SiO(2)). When nanoparticles were present in neutral water, a relatively weak electrolyte concentration (0.01 M KCl) could result in their aggregation; however, with the addition of 1 mg/L NOM, the negative surface charge of nanoparticles increased significantly and therefore their propensity to aggregate is reduced. 4 mg/L NOM stabilized most nanoparticles by producing -30 mV or higher zeta potentials. On the other hand, the negative charge that NOM imparted to nanoparticles could be neutralized by divalent cations (calcium ions). 0.04 M-0.06 M Ca(2+) induced the aggregation of NOM-coated nanoparticles. It should be noted that among all the studied nanoparticles, SiO(2) exhibited the unique stability due to its low NOM adsorption capacity and small Hamaker constant. SiO(2) remained stable no matter whether the solution contained NOM or Ca(2+).

[1]  P. C. Hiemenz,et al.  Principles of colloid and surface chemistry , 1977 .

[2]  Leonard Sweet,et al.  Nanotechnology—Life-Cycle Risk Management , 2006 .

[3]  Charles R. O'Melia,et al.  Natural organic matter and colloidal stability: Models and measurements , 1993 .

[4]  Kiril Hristovski,et al.  Stability of commercial metal oxide nanoparticles in water. , 2008, Water research.

[5]  G. G. Leppard,et al.  Characterization of Submicrometre Colloids in Freshwaters: Evidence for Their Bridging by Organic Structures , 1993 .

[6]  H. Jeng,et al.  Toxicity of Metal Oxide Nanoparticles in Mammalian Cells , 2006, Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering.

[7]  Donald R. Rowe,et al.  Handbook of Wastewater Reclamation and Reuse , 1995 .

[8]  Ann Thayer.  insights: Synergy: Overused, Underrealized , 2000 .

[9]  Jae-Hong Kim,et al.  Natural organic matter stabilizes carbon nanotubes in the aqueous phase. , 2007, Environmental science & technology.

[10]  Paul Westerhoff,et al.  Nanoparticle silver released into water from commercially available sock fabrics. , 2008, Environmental science & technology.

[11]  K. Donaldson,et al.  Inhalation of poorly soluble particles. II. Influence Of particle surface area on inflammation and clearance. , 2000, Inhalation toxicology.

[12]  A. E. Greenberg,et al.  Standard methods for the examination of water and wastewater : supplement to the sixteenth edition , 1988 .

[13]  J. Lewis.  Colloidal Processing of Ceramics , 2004 .

[14]  Y. Chiang,et al.  Comparisons of Hamaker constants for ceramic systems with intervening vacuum or water : From force laws and physical properties , 1996 .

[15]  Menachem Elimelech,et al.  Influence of humic acid on the aggregation kinetics of fullerene (C60) nanoparticles in monovalent and divalent electrolyte solutions. , 2007, Journal of colloid and interface science.

[16]  B. Nowack,et al.  Occurrence, behavior and effects of nanoparticles in the environment. , 2007, Environmental pollution.

[17]  J. Crittenden,et al.  Enhanced Accumulation of Arsenate in Carp in the Presence of Titanium Dioxide Nanoparticles , 2007 .

[18]  M. Elimelech,et al.  Aggregation kinetics of alginate-coated hematite nanoparticles in monovalent and divalent electrolytes. , 2006, Environmental science & technology.

[19]  Pratim Biswas,et al.  Assessing the risks of manufactured nanomaterials. , 2006, Environmental science & technology.

[20]  E. Tipping,et al.  The aggregation of silica and haematite particles dispersed in natural water samples , 1996 .

[21]  Colin L. Raston,et al.  Green chemistry and the health implications of nanoparticles , 2006 .

[22]  Robert N Grass,et al.  In vitro cytotoxicity of oxide nanoparticles: comparison to asbestos, silica, and the effect of particle solubility. , 2006, Environmental science & technology.

[23]  C. Bernhardt.  Preparation of suspensions for particle size analysis. Methodical recommendations, liquids and dispersing agents , 1988 .

[24]  Fadri Gottschalk,et al.  Studying the potential release of carbon nanotubes throughout the application life cycle , 2008 .

[25]  J. Buffle,et al.  Kinetics of Hematite Aggregation by Polyacrylic Acid: Importance of Charge Neutralization , 1995 .

[26]  Montserrat Filella,et al.  Coagulation/sedimentation of submicron iron particles in a eutrophic lake , 1995 .

[27]  M. Wiesner,et al.  Aggregation and Deposition Characteristics of Fullerene Nanoparticles in Aqueous Systems , 2005 .

[28]  J. Raper,et al.  Structure and kinetics of aggregating colloidal haematite , 1990 .