Adsorption and Release of Contaminants onto Engineered Nanoparticles

1. Adsorption and Release of Contaminants onto Engineered Nanoparticles Mason Tomson Civil and Environmental Engineering Department Rice University Houston, TX Start July 1, 2004

2. Objective and Benefit • Largely Avoidable: The overarching goal of research proposed is to create the information needed to insure that avoidable deleterious outcomes of nanomaterial production and use never materialize. • Develop the information needed to predict the risk of nanomaterials. • Adsorption and desorption of contaminants. • Impact of naturally occurring sorbents, NOM, heavy metals, surfactants. • Fate of nanoparticles in soil and water.

3. Adsorption/Desorption Hysteresis Biodegradation Volatilization Uptake Reaction Toxicity Desorption

4. Cl4-Ben Cl2-Ben Aqueous Cl4-PCB Cl2-PCB Toluene Cl6-Ben Cl6-But Naph Phen DDT Solubility (mg/L) TCE PCE Ben Boston Harbor: 106 105 104 103 102 1. Phenanthrene 5 10 KOC=107 Irreversible 2. Pyrene SQC 3. Cl -PCB 5 4. Cl -PCB 6 3 10 Reversible Solid Phase Conc (mg/Kg -OC) Lake Charles, LA : SQC 5. Cl -Benzene 2 6. Cl -Benzene 3 10 Example: 7. Cl -Benzene 4 MCL (WQC) for 8. Cl -Benzene 6 p-Cl -Benzene with 9. Cl -Butadiene 2 6 Koc ~1000 0.1 10 -3 10 10 0.1 10 1000 -7 -5 Solution Phase Conc (mg/L) Adsorption/Desorption Hysteresis

5. "Unweathered, "Weathered, non-remediated, or freshly contaminated" Sediment remediated, or aged" max Sediment max Rev. Irr. 6 0 60 5 0 50 (µg/g) (µg/g) Irr. 4 0 Rev. 40 3 0 30 Water Water 2 0 20 max 1 0 10 ~ ~ max Rev. Irr. Rev. Irr. 30 30 20 20 (µg/ml) (µg/ml) 10 10 0.02 0.02 0.01 0.01

6. Approach and Methodology Oxic/Anoxic Batch Apparatus Column Apparatus

7. C60 large aggregates C60 small aggregates C60 colloidal particles Adsorption of Organic Contaminants from Solution to C60 Fullerene Batch Adsorption/Desorption Study:

8. Fate of Contaminants Adsorbed to Carbon Nano-Particles nC60 colloids Will the sorption and desorption of organic compounds to fullerene particles cause enhanced environmental contaminant transport? nC60 is hydrophilic, mobile & nonextractable Sorption/desorption isotherm: 1. Fullerene particles  2. Other Carbon  3. Soil organic carbon  Sorption of organic contaminants to fullerene particles is the same as to soil organic matter and to activated carbon. When fullerene particles migrate, contaminant transport will be enhanced. (Wiesner, 2004)

9. What Happened During Adsorption? Naphthalene adsorption aggregation Clusters Aggregation & Naph. Entrapment Small Fullerene Aggregates Naphthalene Adsorption

10. Ads Des Adsorption/Desorption of Cd to Soil Reversible Irreversible

11. Sorption/Desorption of As to Magnetite Nano Advantage: Disposal, no desorption bleed-off at low concentration. New Standards: USEPA (10 mg/L); State of N. J. (5 mg/L)

12. Hysteretic Desorption and Below Dose No Toxicity Effects Hormesis Effect: No toxicity at low dose (Calabres, 2003) Hysteretic contaminant releases from sequestrated nano-particles may not harmful to the ecological environment.

13. Nano Advantages: Related to Contaminant Removal and Solids Disposal • Between 10 and 30 times less solid to remove As (III/V) from water. • Virtually no bleed-off: Once As (III/V) is adsorbed to nano-magnetite, desorption is orders of magnitude less than from bulk magnetite. This is an enormous disposal advantage. Mass of Magnetic Needed For Similar Total As Removal 4 nm 20 nm 3000 nm

14. Competitive Adsorption - Natural Water Lake Houston: Drinking water reservoir for Houston Future research direction: Importance of competative processes, organic matter, other heavy metals, silicates, and various forms of phosphates

15. Expected Benefits • Provides the information needed to assess whether this risk is substantial for nanoparticles disposed of in groundwaters. • Yields the necessary parameters to understand the fate of engineered nanoparticles in the environment. • Yields the necessary parameters for future development of risk assessment of the engineered nanoparticles.