1
NANOPRODUCTS OR NANOMATERIALS CAN: Desalinate water Treat pollutants. Make solar cells much more cost efficient Save fuel Reduce materials used for production. Reduce pollution from energy generation. Help conserve fossil fuels. Enhance battery life (that could lead to less material use and less waste). 2
WHERE CAN WE USE SENSORS TO HELP THE ENVIRONMENT? POSSIBILITIES Nanotechnology has the potential to substantially benefit environmental quality and sustainability through Pollution Prevention Pollution Treatment Pollution Remediation 3
PREVENTION Involved in making a manufacturing process environmentally benign. An environmentally benign material or manufactured product that replaces toxic substances or minimizes raw materials. PREVENTION Synthetic or manufacturing processes which can occur at ambient temperature and pressure. Use of non-toxic catalysts with minimal production of resultant pollutants. Use of aqueous-based reactions. Build molecules as needed -- just in time. Nanoscale information technologies for product identification and tracking to manage recycling, remanufacture, and end of life disposal of solvents 4
POLLUTION TREATMENT 5
NANOFILTRATION Nano-membrane filtration process for surface water and fresh groundwater softening and removal of disinfection Variety of materials can be used to make the membrane No extra sodium ions, as used in ion exchangers Many separation processes do not operate at room temperature as nanofilteration (e.g.distillation) NANOFILTRATION 6
AIR POLLUTION FILTERS There are two major ways in which nanotechnology is being used to reduce air pollution: Catalyst: Nanotechnology can improve the performance and cost of catalysts used to transform vapors escaping from cars or industrial plants into harmless gasses. Nanostructured membranes: Being developed to separate carbon dioxide from industrial plant exhaust streams. AIR POLLUTION Remember surface areas! Using crystals containing nano sized pores to trap carbon dioxide. Reducing the amount of platinum used in catalytic converters. Converting carbon dioxide to methanol which can be used to power fuel-cells. Reducing emissions from power plants by converting carbon dioxide into nanotubes. 7
GAS PERMEATION - NANOCOMPOSITES NANOREMEDIATION Explored to treat ground water, wastewater, soil, sediment, or other contaminated environmental materials Nanoparticle agents are brought into contact with the target contaminant under conditions that allow a immobilizing reaction Nano-size partallows nanoparticles to enter small pores in soil or sediment that larger particles might not penetrate Target contaminants include organic molecules such as pesticides or organic solvents and metals such as arsenic or lead 8
TREATMENT & REMEDIATION IRON TREATMENT WALLS Used in groundwater treatment for many years. End-of-pipe management and cleanup of pollution Iron chemically reduces organic and inorganic environmental contaminants. Currently involves granular iron ( 50 mm or 50,000 nm). Nanosized iron enhances the reaction. Enhanced further by coupling with other metals (Fe/Pd)* on the nanoscale. Nano Fe 0 is more reactive and effective than the microscale. Smaller size makes it more flexible -- penetrates difficult to access areas. * Elliot and Zhang ES&T 2001, 35, 4922-4926 SENSE AND SHOOT APPROACH TO POLLUTION TREATMENT. SMART MATERIALS Nanosized zinc oxide (ZnO) senses organic pollutants indicated by change in visible emission signal The ZnO shoots the pollutants via photocatalytic oxidation to form more environmentally benign compounds. Sensing capability means that the energy-consuming oxidation stage only occurs when the pollutants present. >300 nm UV Kamat, P.V, et al. J.Phys.Chem. B 2002, 106,788-794. 9
SENSORS Nanomaterial sensors much more sensitive (WHY?????) Need to be low cost, rapid, precise and ultrasensitive Operate in real time Example we have seen, in health care SENSORS Nanomaterial sensors much more sensitive (WHY?????) Need to be low cost, rapid, precise and ultrasensitive Operate in real time Example we have seen, Molecules adsorb on surface of micro cantilever, causes a change in surface stress, cantilever bends Applications to bio-toxins as well. Used to detect chemicals using either a specific reaction between analyte and sensor layer or chem/physisorption processes. Single Molecule Detection Possible 10
LIGHT WEIGHT, STIFF, STRONG MATERIALS Less weight Stronger, stiffer materials More fuel efficient, bette payloads New nanomaterials Better high temperature capabilities More fuel efficient, less pollution More durable Longer life, less pollutio 11
& NANOTECHNOLOGY AND THE ENVIRONMENT Nature of nanoparticles themselves Characteristics of the products made. Remember, these change as we go nano Manufacturing processes involved in nano-xyz What materials used? What waste? Toxic substances used? What happens when nano-xyz gets into the air, soil, water,? 12
NANO CONTAINMENT The Wind 13
The Water Landfill 14
RECYCLABILITY? 15