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Adsorption/Desorption of Pollutants to Nanoparticles

Adsorption/Desorption of Pollutants to Nanoparticles. Mason Tomson, V. L. Colvin Xuekun Cheng, Y. Gao, R. Wahi, A. T. Kan Center for Biological and Environmental Nanotechnology Civil and Environmental Engineering and Chemistry Departments Rice University September 15, 2003.

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Adsorption/Desorption of Pollutants to Nanoparticles

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  1. Adsorption/Desorption of Pollutants to Nanoparticles Mason Tomson, V. L. Colvin Xuekun Cheng, Y. Gao, R. Wahi, A. T. Kan Center for Biological and Environmental Nanotechnology Civil and Environmental Engineering and Chemistry Departments Rice University September 15, 2003

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

  3. Black Carbon

  4. Naphthalene/Lula 2.5 2.0 1.5 (µg/g) 1.0 Solid Phase Conc 0.5 0.0 0.0 0.2 0.5 0.8 1.0 Solution Phase Conc (µg/ml) Sorption/Desorption Hysteresis > des ads K K p p Desorption Adsorption

  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. 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

  7. Flow In: Naphthalene 0.1ug/ml 22% Naphthalene adsorbed Flow Out: Naphthalene Fullerene C60 Column Naphthalene Adsorption onto Original C60 Particles E. Ballesteros et al. 2000 J. Chromatography A — Little adsorption from naphthalene aqueous solution onto fullerene C60 particles was found... Kp ~ 10

  8. C60 small aggregates Toluene extraction C60 colloidal particles Toluene No extraction C-18 Sep-Pak® No adsorption Carbon Nano-Particle Transport

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

  10. UV/Vis Spectrum of C60 in Toluene Sampled from small aggregates 407nm 424nm 690nm

  11. Naphthalene-Carbon Adsorption Isotherms (1) Activated carbon (2) Large aggregates q=105.20C0.31 q=102.39C (3) Small aggregates (3) Colloidal C60 q=104.27C0.44 q=103.75C

  12. Adsorption/Desorption of Naphthalene(Small Aggregated and Colloidal C60 Particles) Small aggregates Colloidal C60 Desorption Desorption Adsorption Adsorption

  13. Adsorption/Desorption of Naphthalene to Small Aggregated C60 Particles

  14. Cl4-PCB Cl2-PCB Toluene Cl6-Ben Cl4-Ben Cl2-Ben Cl6-But Naph DDT Phen Aqueous TCE PCE Ben ads des Solubility (mg/L) Boston Harbor: 106 105 104 103 102 Koc= 107 1. Phenanthrene 5 10 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 Naphthalene 2 6. Cl -Benzene 3 10 7. Cl -Benzene Example: 4 MCL (WQC) for 8. Cl -Benzene 6 p-Cl -Benzene with 9. Cl -Butadiene 2 6 Koc ~1000 0.1 10 10 0.1 10 1000 -7 -5 10 -3 Solution Phase Conc. (mg/L) Adsorption and Desorption of Organic Contaminants Naturally occurring soil organic carbon C60 Fullerene 105 103 10 0.1 Solid phase conc. (mg/g) Solution Phase Conc. (mg/ml) Solid Lines Represent the Rice University Dual Equilibrium Model

  15. C60 small aggregates Toluene extraction C60 colloidal particles Toluene No extraction C-18 Sep-Pak® No adsorption Carbon Nano-Particle Transport

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

  17. What Happened During Desorption? “Loosely” Adsorbed Naphthalene “Entrapped” Naphthalene desorption

  18. Possible Explanations • Two parts of adsorption/desorption: q1: adsorption onto surfaces q2: entrapment in clusters • q1 account for  11% adsorption; • q2 account for  89% adsorption • Possibility of adsorption/desorption hysteresis • Adsorption/desorption hysteresis needs further study

  19. Adsorption of Cadmium to Anatase Nanoparticles

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

  21. Physical Characteristics of Anatase

  22. TEM Images of Anatase Large Crystals Nanoparticles (RHT-69)

  23. Large crystals Nanoparticles Adsorption of Cadmium to Large and Nano-Anatase

  24. Langmuir Adsorption Isotherm Parameters

  25. Adsorption/Desorption Reversibility Nanoparticles Large Crystals RHT 69 Sigma

  26. Electrochemical Properties Reported pzc: 5.8 - 6.1 pH

  27. Surface Charges and pH Adsorption Edge Potential Titration TiO2 suspension Cd adsorption vs. pH

  28. Summary • States of aggregation of nanoparticles may change in various aqueous environment • Adsorption of contaminants to the surfaces of nanoparticles is very strong • Adsorption/desorption of organic compounds to nanoparticles might be hysteretic • Adsorption/desorption of heavy metals onto/from nanoparticles are predictable based on surface area normalized sorption isotherm • Nanomaterials in natural aqueous environments may affect the fate and transport of contaminants substantially

  29. Future • Responsible Use • Remediation

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