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Effect of dissolved organic matter on the stability of magnetite nanoparticles under different pH and ionic strength conditions.
Sci Total Environ. 2010 Jul 15; 408(16):3477-89.ST

Abstract

Upon release of engineered nanoparticles (NPs) into the subsurface environment, their fate and transport and hence their potential environmental and public health impacts will largely depend on how stable these NPs are as suspended particles in the natural environment. In this study, we systematically examine the effect of humic acid (HA) on surface charge status and aggregation potential of magnetite (Fe(3)O(4)) NPs, selected as a model for metal oxide NPs, over a wide range of solution pH and ionic strength. Through zeta potential (ZP) measurements, we found that HA can adsorb to magnetite particles hence modifying their surface charge status. At low loadings, the presence of HA can induce a shift in the point zero of charge of due to partial neutralization of the positive charges on magnetite NPs. At high loadings, however, HA is capable of completely cover magnetite particles giving rise to a suspension ZP profile similar to its own (observed in presence of 20 mg L(-)(1) HA). These impacts on surface charge correspond well with the observed aggregation behaviors in the absence and presence of HA. From the dynamic light scattering (DLS) measurements, fast aggregation, which is independent of solution chemistry, took place when the pH is close to the point zero charge (PZC) and the ionic strength is above the critical coagulation concentration (CCC). At high ionic strength, a small dose (2 mg L(-)(1)) of HA stabilized the NPs' suspension significantly. This stabilization effect is substantially enhanced with increasing HA concentration. The calculated DLVO (Derjaguin-Landau-Verwey-Overbeek) interaction energy profiles, using experimentally determined values of Hamaker constant, adequately support the experimental observations. The DLVO analysis further reveals the possible presence of secondary energy minima and the possibility of deaggregation of magnetite agglomerates. The complexation of HA-NPs and the HA effects on NPs aggregations were confirmed by atomic force microscope (AFM) observations.

Authors+Show Affiliations

Laboratory for Earth Surface Processes (LASP), College of Urban and Environmental Sciences, Peking University, Beijing, 100871, China.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

20421125

Citation

Hu, Jun-Dong, et al. "Effect of Dissolved Organic Matter On the Stability of Magnetite Nanoparticles Under Different pH and Ionic Strength Conditions." The Science of the Total Environment, vol. 408, no. 16, 2010, pp. 3477-89.
Hu JD, Zevi Y, Kou XM, et al. Effect of dissolved organic matter on the stability of magnetite nanoparticles under different pH and ionic strength conditions. Sci Total Environ. 2010;408(16):3477-89.
Hu, J. D., Zevi, Y., Kou, X. M., Xiao, J., Wang, X. J., & Jin, Y. (2010). Effect of dissolved organic matter on the stability of magnetite nanoparticles under different pH and ionic strength conditions. The Science of the Total Environment, 408(16), 3477-89. https://doi.org/10.1016/j.scitotenv.2010.03.033
Hu JD, et al. Effect of Dissolved Organic Matter On the Stability of Magnetite Nanoparticles Under Different pH and Ionic Strength Conditions. Sci Total Environ. 2010 Jul 15;408(16):3477-89. PubMed PMID: 20421125.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effect of dissolved organic matter on the stability of magnetite nanoparticles under different pH and ionic strength conditions. AU - Hu,Jun-Dong, AU - Zevi,Yuniati, AU - Kou,Xiao-Ming, AU - Xiao,John, AU - Wang,Xue-Jun, AU - Jin,Yan, Y1 - 2010/04/24/ PY - 2009/07/27/received PY - 2010/02/23/revised PY - 2010/03/19/accepted PY - 2010/4/28/entrez PY - 2010/4/28/pubmed PY - 2010/10/6/medline SP - 3477 EP - 89 JF - The Science of the total environment JO - Sci. Total Environ. VL - 408 IS - 16 N2 - Upon release of engineered nanoparticles (NPs) into the subsurface environment, their fate and transport and hence their potential environmental and public health impacts will largely depend on how stable these NPs are as suspended particles in the natural environment. In this study, we systematically examine the effect of humic acid (HA) on surface charge status and aggregation potential of magnetite (Fe(3)O(4)) NPs, selected as a model for metal oxide NPs, over a wide range of solution pH and ionic strength. Through zeta potential (ZP) measurements, we found that HA can adsorb to magnetite particles hence modifying their surface charge status. At low loadings, the presence of HA can induce a shift in the point zero of charge of due to partial neutralization of the positive charges on magnetite NPs. At high loadings, however, HA is capable of completely cover magnetite particles giving rise to a suspension ZP profile similar to its own (observed in presence of 20 mg L(-)(1) HA). These impacts on surface charge correspond well with the observed aggregation behaviors in the absence and presence of HA. From the dynamic light scattering (DLS) measurements, fast aggregation, which is independent of solution chemistry, took place when the pH is close to the point zero charge (PZC) and the ionic strength is above the critical coagulation concentration (CCC). At high ionic strength, a small dose (2 mg L(-)(1)) of HA stabilized the NPs' suspension significantly. This stabilization effect is substantially enhanced with increasing HA concentration. The calculated DLVO (Derjaguin-Landau-Verwey-Overbeek) interaction energy profiles, using experimentally determined values of Hamaker constant, adequately support the experimental observations. The DLVO analysis further reveals the possible presence of secondary energy minima and the possibility of deaggregation of magnetite agglomerates. The complexation of HA-NPs and the HA effects on NPs aggregations were confirmed by atomic force microscope (AFM) observations. SN - 1879-1026 UR - https://www.unboundmedicine.com/medline/citation/20421125/Effect_of_dissolved_organic_matter_on_the_stability_of_magnetite_nanoparticles_under_different_pH_and_ionic_strength_conditions_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0048-9697(10)00304-9 DB - PRIME DP - Unbound Medicine ER -