NANOTECHNOLOGY SOLID WASTE IMPLICATIONS. Gurumurthy Ramachandran. University of Minnesota

Transcription

1 NANOTECHNOLOGY SOLID WASTE IMPLICATIONS Gurumurthy Ramachandran University of Minnesota

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3 Engineering at the Atomic Level: Scanning Tunneling Microscopy Manipulating atoms Writing with atoms. D.M. Eigler, E.K. Schweizer. Positioning single atoms with a scanning tunneling microscope. Nature 344, (1990).

4 Royal Society and Royal Academy of Engineers Nanotechnology Report, 2004 Nanoscience The study of phenomena and manipulation of materials at atomic, molecular and macromolecular scales, where properties differ significantly from those at a larger scale Nanotechnologies The design, characterization, production and application of structures, devices and systems by controlling shape and size at nanometre scale.

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6 Unique Structures and Morphologies Single Walled Carbon Nanotubes

7 Significance of the nanoscale Nanoscale = 100 nm to the size of atoms (0.2 nm) At this scale, the properties of materials can be very different from those at a larger scale. Increased relative surface area 30 nm particle = 5% of atoms on surface 10 nm particle = 20% of atoms on surface 3 nm particle = 50% of atoms on surface Quantum effects Dominate as size becomes small. Physical and chemical properties change dramatically.

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12 Nanoparticles deliver treatments to targeted sites, including places where standard drugs do not reach. Gold nanoshells targeted to tumors might, when hit by infrared light, heat up enough to destroy the tumors. Improved contrast agents would detect problems at earlier, treatable stages. For example, reveal tumors (red) only a few cells in size. Nano-scale modifications of implant surfaces would improve implant durability and biocompatibility. An artificial hip coated with nanoparticles might bond better with the surrunding bone

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15 Health and Ecological Risks from Nanoparticles The same properties that make nanoparticles attractive in new materials synthesis (high reactivity and ability to cross cell membranes) also could lead to adverse health and ecotoxicological effects

16 NANOPARTICLES Special physical/chemical properties:- Smaller particles in this size range more reactive than large particles of the same material maybe due to higher surface area per unit mass Chemical composition, e.g., transition metals on surfaces Morphology Small sizes also cause greater degree of translocation within body.

17 Possible exposure routes for nanoparticles based on current and potential future applications The Royal Society, 2004

18 Life Cycle Impact Assessment Persistent toxicity leading to chronic effects in humans Acute toxicity to humans Eco-toxicity Landfill/incineration for waste, air, water, and groundwater pollution

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20 Environmental Laws Clean Air Act and Clean Water Act: Set standards and to enforce them through permits issued to pollution sources. RCRA: Sets technology standards for disposal sites and establishes a cradle-tograve reporting system for hazardous wastes.

21 Applicability of RCRA to Nanowastes American Bar Association RCRA offers broad statutory authority to EPA to regulate wastes containing nanoparticles. What happens if EPA s current regulatory definitions of hazardous characteristics (ignitability, corrosivity, reactivity, and toxicity) fail to encompass unexpected risks from nanoscale materials? EPA may also need to assess whether it should define new hazardous characteristics to reflect these new risks.

22 Listed Hazardous Waste? Wastes generated either by specific industrial activities and uses (F and K wastes) or by the discarding of commercial chemicals (U and P wastes) Neither category of listings expressly addresses wastes containing nanoscale materials or wastes from nanomaterials manufacturing.

23 May affect Process of listing/delisting EPA currently adds solid wastes to the hazardous waste listings based on whether they (1) exhibit a hazardous characteristic; (2) display acute toxic effects on humans or rats; or (3) pose a substantial present or potential hazard to human health or the environment when improperly managed. Nanomaterials may display unique characteristics that EPA s current regulatory factors or computer models may not accurately predict, the listing process and delisting procedures may inappropriately over- or under-predict environmental risks.

24 Quantity of hazardous wastes RCRA requirements for generators vary based on the amount of hazardous waste that they generate in a calendar year. Small quantity generators have exemptions from many requirements. However, nanomaterials may present novel risks at sufficiently small quantities.

25 Opportunities for cleaning up hazardous wastes and contamination Nanoscale iron particles have proven effective at reducing concentrations of persistent chlorinated organic compounds in groundwater. Nanomaterials to design environmental detectors and sensors that can identify small concentrations of toxic compounds in the environment.

26 EPA Developments: General Draft Nanotechnology White Paper(Dec 2005) Expert Panel Review (April 2006) Adequate review of existing science but fails to include policy and regulatory recommendations, in the short or long term Awaiting final version; not expected to include policy or regulatory recommendations

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