Lesson 6: Environmental Process Assessment (and Nanotechnology)

Transcription

1 Lesson 6: Environmental Process Assessment (and Nanotechnology) Lecture 10 Nanotechnology an Introduction NanoTech introduction:// Christine S. Grant, Ph.D. Professor of Chemical and Biomolecular Engineering North Carolina State University College of Engineering Raleigh, North Carolina, USA

2 Nanotechnology Media : Xenon on Nickel (110) Nanotechnology: The ability to see, measure and make objects that are within the same tiny size scale as atoms and molecules. The nanotechnology realm can be defined as being between 0.1 nanometer (about the size of a hydrogen atom) and 100 nanometers (about the size of a virus). UC Berkeley chemistry Professor Paul Alivisatos, 44, directs the Molecular Foundry at Lawrence Berkeley Laboratory, where researchers use powerful new tools to advance the molecular control of materials. Alivisatos is a pioneer in the construction of nanoscale semiconductor crystals that can be used to make next-generation solar cells, or minuscule fluorescent labels that may some day help surgeons distinguish tumors from healthy tissue.

3 Nanotechnology: Other Definitions Millimeter: One thousandth of a meter. About 4/100 inch. Molecular electronics: Any system with atomically precise electronic devices of nanometer dimensions, especially if made of discrete molecular parts rather than the continuous materials found in today's semiconductor devices. Nanocrystal: A nanoscale crystal whose size, shape and atomic composition are carefully controlled to yield specific properties, like absorption of specific wavelengths of light. Nanometer: One-billionth of a meter. Self-assembly: The ability of objects to assemble themselves into an orderly structure. Routinely seen in living cells, this is a property that nanotechnology may extend to inanimate matter.

4 NanoActive Aluminum Oxide NanoActive Al2O3 is produced using proprietary processes to obtain high specific surface area, low density, amorphous material with high adsorption capacity and chemical reactivity. NanoActive Al2O3 can be dispersed in various carrier fluids with greatly reduced particle sizes. Appearance/Color White Powder Specific Surface Area (BET) 275 m2/g Crystallite Size Amorphous Average Pore Diameter 28 Å Total Pore Volume 0.15 cc/g Bulk Density 0.5 g/cc True Density 3.9 g/cc Mean Aggregate Size, d µm Loss on Ignition 2.1% Al Content (Based on Metal) >99.8% Volume weighted mean aggregate size = 1.9 µm.

5 NanoActive Aluminum Oxide NanoActive Al2O3 is produced using proprietary processes to obtain high specific surface area, low density, amorphous material with high adsorption capacity and chemical reactivity. NanoActive Al2O3 can be dispersed in various carrier fluids with greatly reduced particle sizes.

6 Nanotechnology Industry at a glance -- Total companies involved in nanotech worldwide: 1,000 or more. -- U.S. companies involved in nanotech: More than Public companies: Fewer than 20 claim to focus solely on nanotech, but more than 100 public companies have nanotech R&D initiatives. -- Jobs: More than 1,700 jobs created through venture capital investing in the past four years. -- Federal funding: $465 million in 2001, $697 million in 2002, $774 million in 2003, $849 million in (President Bush recently signed a four- year, $3.7 billion funding bill for nanotechnology.) -- U.S. patents with the word "nano" in 2002: 1000, up from slightly more than 700 in

7 Nanotechnology -- Revenue: The NanoBusiness Alliance estimates that global nanotech revenue has already surpassed $45 billion. Economists at the National Science Foundation estimate that nanotech could yield a trillion-dollar global market by State funding: The California Institutes for Science and Innovation have spent $400 million to date on UC buildings to house cutting-edge research, including nanotech. One effort dedicated totally to nanotech is the California Nanosystems Institute, a joint project of UC Santa Barbara and UCLA. Nanotech introduction environmental

8 Nanotechnology Pro and Con Pro: 1. Nanomaterials also enable green chemistry and exact manufacturing from the bottom up atom by atom. Avoid creation of hazardous waste and large quantitites of toxic raw materials, Creation of less- toxic products 2. Nano-remediation: - simple implementation ( injection of nano-slurry), high surface area for interaction with pollutants. Con: 1. Nanotubes are biologically active and possibly toxic 2. Nanoparticles can accumulation in the nasal passages, lungs, and brains of rats 3. Even if nanoparticles are encapsulated in or use polymers as a support if there a possibility that the nanoparticles can separate and enter the environment as a free particle?

9 Develop 10 critical Green Processing/ Environmental Questions associated with Nanotechnology (Answer 2 questions) 1. What are the key issues related to the biocompatibility vs. the toxicity of nanomaterials? The NTP is an interagency program whose mission is to evaluate agents of public health concern by developing and applying tools of modern toxicology and molecular biology. The program maintains an objective, science-based approach in dealing with critical issues in toxicology and is committed to using the best science available to prioritize, design, conduct, and interpret its studies. To that end, the NTP is continually evolving to remain at the cutting edge of scientific research and to develop and apply new technologies.

10 Substances Nominated to the NTP for Toxicological Studies and Testing Recommendations Made by the NTP Interagency Committee for Chemical Evaluation and Coordination (ICCEC) on June 10, 2003 Substance [CAS No.] Nominated by Nominated for Rationale for Nomination ICCEC Recommendations Nanoscale materials [No CAS No.] Rice University Center for Biological and Environmental Nanotechnolog y -Toxicological characterizatio n of several representative classes of nanomaterials Intense current and anticipated future research and development focus; further studies and development of appropriate toxicological methods are needed to adequately assess health effects Toxicological studies: -Size- and compositiondependent biological disposition of nanocrystalline fluorescent semiconductor materials -Toxicological characterization of high aspect ratio carbon nanomaterials -Role of particle core and surface composition in the immunotoxicity of the above listed materials -Phototoxicity of representative metal oxide nanoparticles

11 Environmentally Responsible Development of Nanotechnology How the U.S. government is dealing with the immediate and long-term issues of this new technology. Mihail C. Roco, National Science Foundation: U.S. National Science and Technology Council Subcommittee on Nanoscale Science, Engineering, and Technology How to assemble nanowires in situ and fabricate nanoscale components into circuits without intermediate handling of the components, thus reducing the exposure risks during manufacturing (23).

12 Long-term thinking on Nanotechnology Several issues that are related to responsible development of nanotechnology hinge on broader social and economic outcomes and require more time to be addressed. Government and civic organizations must work together to ensure an equitable and responsible strategy for addressing these issues. Respect for human nature, dignity, and physical integrity. Society should co-evolve harmoniously with nanoscale technology (18, 19). Our rights to a good quality of life, long-term health and safety, and access to knowledge must be respected. The implications of the convergence of nanotechnology, biotechnology, information technology, cognitive science, and other technologies are important because nanoscale knowledge and tools enable and unify other transforming technologies at their foundations (20). Nanovideo

13 Long-term thinking on Nanotechnology Balancing R&D nanotechnology investment. Research should be conducted in such a way that the benefits and secondary consequences are fairly distributed throughout society. Examples include equitable access to advanced medicine and other nanotechnology services and products. NNI has this goal in mind (2, 7, 21). In addition, economic risks must be addressed: the loss of production because of polluted water and air, increased restrictions on the extraction of raw materials, limits on the use of polluted real estate, requirements to clean up existing pollution, and public opposition to industrial development. Early nanotechnology education and training should be focused on basic concepts, be interdisciplinary, and be relevant to preparing the workforce (22).

14 If nanoparticles are released into the environment, how far will they get? To what extent would nanoparticles be transported in the environment, for example when suspended in groundwater? Mark Wisener of Rice University in Houston, Texas and co-workers have studied this issue in the lab by passing various nanoparticles in water through a column packed with glass beads about a third of a millimetre across, mimicking the mineral grains of a sandy aquifer. They find that different types of nanoparticle can travel significantly different distances through the porous medium before becoming stuck to the surface of the beads. Wiesner and colleagues suspended eight types of nanoparticle in water containing a small amount of salt and buffered to ph 7, which was a good approximation to the fluid in many freshwater aquifers.

15 If nanoparticles are released into the environment, how far will they get? To what extent would nanoparticles be transported in the environment, for example when suspended in groundwater? They investigated fullerenes (which aggregated into clusters about nm across), hydroxylated fullerenes (fullerols, with OH groups on the molecules' surfaces), single-walled carbon nanotubes, silica (57 and 135 nm in size), anatase (titanium dioxide, used in sun creams), and ferroxane and alumoxane, which are respectively hydrated iron and aluminium oxide coated with acetic acid. One way of measuring the mobility of the particles is to use the experimental results for transport through a porous column of beads to calculate how far the suspension would have to flow before the concentration of nanoparticle. So although nanotubes prove to be among the most mobile nanoparticles tested, it is not yet clear whether they would be harmful as a groundwater contaminant.

16 If nanoparticles are released into the environment, how far will they get? To what extent would nanoparticles be transported in the environment, for example when suspended in groundwater? Air pollution and abiity to measure &p=3cb6151f86700ab2&index=9