CLEANING UP WITH NANOTECH: Focus on nanotechnology in the cleantech sector.
- Filtration
- Catalysts
- Water treatment
- Air purification
- Sensors
- Membranes
Nanomaterials in environmental applications
Nanomaterials have the potential to benefit environmental quality and sustainability, through pollution prevention, treatment and remediation. Such benefits include improved detection and sensing, removal of the finest contaminants from air, water and soil, and the creation of new industrial processes which reduce waste products and are themselves “green”. Metal oxide nanopowders can be of benefit to environmental protection in areas such as reducing use of raw and manufactured materials (dematerialisation), minimising or eliminating the generation of wastes and effluents and reducing toxics. The environment is also protected in applications which treat waste streams more effectively and remediate existing polluted sites.
Nanomaterials have been gaining increasing interest in the area of environmental remediation because of their unique physical, chemical and biological properties. The control and design of nanomaterials allows for increased affinity, capacity, and selectivity for pollutants. This is a result of the enhanced reactivity, surface area, subsurface transport, and/or sequestration characteristics of nanomaterials. Types of nanomaterials that can be used for environmental treatments include smart modified surfaces or membranes, reactive nanoparticles, molecularly imprinted polymers (MIPs), and nanoscale biopolymers.
However there are a number of challenges before this is even technically feasible, such as increasing the stability of nanoparticles utilized in remediation/treatment methodologies and the need to develop improved methods for monitoring the fate and transport of these materials once they enter the natural environment. Conventional technologies are often inadequate to reduce concentrations in wastewater to acceptable regulatory standards, necessitating the development of novel materials with increased affinity, capacity, and selectivity for heavy metals, which is why reactive nanoparticles appear to be useful in remediating groundwater utilising reactive nanocoated iron.
Nanomaterials are driving the next generation of high performance cleantech technologies. However there are a number of challenges before this is even technically feasible, such as increasing the stability of nanoparticles utilized in remediation/treatment methodologies and the need to develop improved methods for monitoring the fate and transport of these materials once they enter the natural environment.
Conventional technologies are often inadequate to reduce concentrations in wastewater to acceptable regulatory standards, necessitating the development of novel materials with increased affinity, capacity, and selectivity for heavy metals, which is why reactive nanoparticles appear to be useful in remediating groundwater utilising reactive nanocoated iron that quickly breaks down chlorinated organic solvents into harmless by-products. The e potential of selective, nano-sized metal and mineral oxides (1-50 nm) for catalytic degradation of contaminants in water remains unrealized largely due to the difficulty of removing the nanoparticles from aqueous streams. To overcome this limitation, researchers are exploring the generation of hybrid materials wherein the catalytic, inorganic nanoparticles are confined within sub-micron colloidal particles of a thermally-responsive, cross-linked polymer. Smart surfaces are also being developed to address biofouling that not only sense and interact with their environment, but also can fundamentally alter their own behaviour and deactivate themselves as pre-programmed or as desired.
These materials, however, could also lead, possibly, to environmental problems. Knowledge is still at a relatively early of how nanostructured materials, nanoparticles and other related nanotechnologies will interact in the environment. Such interactions may be a function of the nature of nanoparticles themselves, the characteristics of the products made from them, or aspects of the manufacturing process involved.
Water treatment
Nanotech will impact water applications in treatment and remediation, sensing and detection, and pollution prevention. Nano-enabled photocatalysts could replace chlorine to be more effective and much safer alternative oxidation methods to water purification. Photocatalytic oxidation can remove bacteria, organic toxins, dioxins, and other chemicals in our water system without introducing other chemicals.
Air purification
Nanoscale TiO2 photocatalyst coatings and air filter products can control Sick Building Syndrome by removing Volatile Organic Compounds emitted from building materials and furniture and creates a purer space for comfortable living and working condition. Photocatalytic oxidation also reduces hydrocarbon waste produced from industrial factories burning fossil fuel or coal. It is considered as the “Holy Grail” of environmental protection according to many research scientists.
Membranes
Due to their huge surface area, nanoparticles are more effective filtration media than larger particles of the same material and nanomaterials such as carbon nanotubes, nanoparticles, and dendrimers are contributing to the development of more efficient and cost-effective water filtration processes. Nanofiltration processes are capable of removing hardness, heavy metals, NOM, particles and a number of other organic and inorganic substances in one single treatment step.
Sensors
The development of new and enhanced nanosensors is allowing for the detection of biological and chemical contaminants at very low concentration levels in the environment, including water. Nanosensor technology could significantly out-perform current commercial detection devices by up to a 1,000 fold. Nanosensors will allow for rapid and precise process control and environmental monitoring, leading to remote, in-situ, real-time and continuous measurement of species at trace (ppt) concentrations.
Questions & Answers
Q
Who are the companies developing nanotech products for the cleantech industry?
A
A number of leading oil and energy companies are exploring nanomaterials for new energy and environmental technologies. Application developers include Seldontech (filtration), AQUAporin ApS (membranes), NanoH2O (membranes), Matrikx (filtration), Kx Technologies (filtration), Applied Nanotech, Inc. (sensors), Molecular Nanosystems, Inc. (sensors), Nanoselect, Inc. (nanotube water sensors), Porifera, Inc. (nanotube membranes), M.E.R. Corporation ( nanotube filtration), Canano Technologies LLC (nanoscale iron in clean-up of contaminants in groundwater, soil and sediments, heavy metals and in organics), Green Millenium (nanoTiO2 photocatalytic treatments for reducing pollution and cleaning water). There are also a wide range of nanomaterials producers that produce powders for application in filtration media and remediation technologies. Nanomaterials also provide an environmentally friendly alternative for toxic or environmentally unfriendly materials used in a number of industries.
