Impact/Purpose:

particle-adsorbate systems complementary to the aggregation and dissolution experiments will provide fundamental information on surface speciation and surface complexation;

Additional studies using both in situ and ex situ surface spectroscopic investigations of probe molecule adsorption to better understand the surface chemistry and nature of surface sites and surface bonding under different environmental conditions.

particle-adsorbate systems complementary to the aggregation and dissolution experiments will provide fundamental information on surface speciation and surface complexation;

Additional studies using both in situ and ex situ surface spectroscopic investigations of probe molecule adsorption to better understand the surface chemistry and nature of surface sites and surface bonding under different environmental conditions.

The study will be conducted to satisfy four main objectives. These objectives are to:

1. fully characterize a variety of manufactured metal and metal oxide nanoparticles in terms of their size, shape, bulk and surface physicochemical properties;
2. determine under what environmental conditions (ionic strength, pH, ligands, organic matter, surface adsorption and nanoparticle concentration) do manufactured metal oxide and metal nanoparticles of different size and composition aggregate in aqueous solution and measure the size of the aggregates as a function of these environmentally important variables;
3. determine under what environmental conditions (ionic strength, pH, ligands, surface adsorption and solar irradiation) do manufactured metal oxide and metal nanoparticles of different size and composition dissolve in aqueous solutions and;
4. investigate fundamental aspects of the surface properties and surface chemistry of metal oxide and metal nanoparticles as surface properties and surface chemistry will control both nanoparticle aggregation and nanoparticle dissolution as well as impact nanoparticle-biological interactions.

It is clear that the fate of the nanoparticles in aqueous environments will depend on the state of the nanoparticle (i.e. whether the nanoparticle remains isolated, forms aggregates or undergoes dissolution). This is the basis of the hypotheses of the proposed studies.

The first hypothesis of the proposed project is that nanoparticles will form aggregates in solution and that the size of the aggregate will depend on nanoparticle primary size and composition as well as on environmental conditions. To test this hypothesis the following experiments will be completed:

1. Perform dynamic light scattering and sedimentation experiments on a series of metal oxide and metal nanoparticles in aqueous solution as a function of nanoparticle loading under circumneutral pH;
2. Perform a similar series of dynamic light scattering and sedimentation experiments on a series of metal oxide and metal nanoparticles in aqueous solution as a function of ionic strength and pH;
3. Perform a similar series of dynamic light scattering and sedimentation experiments on a series of metal oxide and metal nanoparticles in aqueous solution in the presence of coordinating ligands and complex organic matter;

The second hypothesis of the proposed project is that nanoparticle dissolution can occur under certain conditions that will depend on nanoparticles size and composition as well as on environmental conditions. To test this hypothesis the following experiments will be performed:

1. Perform dissolution studies on a series of metal oxide and metal nanoparticles in aqueous solution as a function of nanoparticle loading under circumneutral pH;
2. Perform dissolution studies on a series of metal oxide and metal nanoparticles in aqueous solution as a function of ionic strength and pH;
3. Perform dissolution studies on a series of met

Description:

As commercial manufactured nanomaterials become more commonplace, we can expect that these manufactured materials have the potential to get into the environment sometime during production, distribution, use or disposal, i.e. sometime during the lifecycle of these materials. In particular, there exists the potential that nanomaterials may make their way into water systems, e.g. drinking water systems, ground water systems, estuaries, lakes etc. Nanoparticles, the primary building blocks of many nanomaterials, are of particular interest in the proposed studies as the fate of nanoparticles in aqueous environments will depend to a large extent on the physical and chemical state of the nanoparticles. A series of experiments will be done to provide the data needed to predict the environmental fate of commercially manufactured metal and metal oxide nanoparticles.

Record Details:

Record Type:PROJECT( ABSTRACT )

Start Date:01/15/2009

Completion Date:01/14/2012

Record ID: 203383

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Related Organizations:

Role :OWNER

Organization Name :UNIVERSITY OF IOWA

Mailing Address :Jessup Hall

Citation :Iowa City

State :IA

Zip Code :52242

Project Information:

Approach :

Manufactured nanoparticles will be purchased from several sources and characterized using a wide variety of techniques and analysis methods so that both bulk and surfaces properties can be understood on a molecular level. These well-characterized particles will then be used in a series of solution-phase studies to determine under what conditions metal oxide and metal nanoparticles aggregate into larger particles and under what conditions do these nanoparticles dissolve. Nanoparticle aggregation and dissolution will be probed using light scattering and elemental analysis methods, respectively. Mathematical analyses using classical kinetic and thermodynamic approaches will be applied to the data. Since nanoparticle surface processes are important in nanoparticle agglomeration and dissolution, fundamental aspects of surface properties and surface chemistry will be investigated using surface-sensitive spectroscopic and other surface-sensitive probes. These fundamental molecular level studies will be important in interpreting the more macroscopic aggregation and dissolution measurements and in determining how well classical approaches can be used to interpret macroscopic behavior of nanoscale materials.

Cost :$389,303.00

Research Component :Nanotechnology

Project IDs:

ID Code :R833891

Project type :EPA Grant