Materials recycling is becoming increasingly sophisticated as require-ments grow to salvage all kinds of materials from products made from all kinds of metals, plastics and paper. But the difficulties involved in extracting valuable materials could soon become a lot more complicated. The emerging technology of nanotechnology, and its use of the tiniest particles, could prove problematic for the recycling industry.
While there are already a number of nanoproducts on the market - such as sunscreens with nanotitanium that better reflect UV rays and carbon nanotubes encapsulated into electrical equipment - the industry is poised to take off dramatically in coming years.
By 2015, the world market for products that contain nanomaterials is expected to reach $2.6 trillion, according to the Institute of Nanotechnology, based in the University of Stirling, Scotland.
The problem is that there is no specific legislation dedicated to the recycling of nanomaterials in Europe, although that is set to change soon. Earlier this year, the European Parliament’s committee on the environment, public health and food safety introduced an amendment to the current Waste Electrical and Electronic Equipment Directive which would further restrict the use of certain hazardous substances. MEPs singled out nanosilver and carbon nanotubes for special controls, and demanded notification, labelling and prevention/prohibition of these components.
Meanwhile, REACH, the European regulation on registration, evaluation, authorisation and restriction of chemical substances, includes a requirement to address the entire lifecycle of a chemical, including its disposal - and this is taken to apply to nanomaterials too. If health and environmental concerns emerge during REACH risk assessments, expect some more tough restrictions on handling nanomaterials to emerge.
The irony is that nanotechnology has been promoted as a technology that will dramatically enhance the recycling properties of everyday products. For example, Sustainpack, an EU-funded consortium of 35 partners from 13 countries representing packaging research associations, academia and industry, is developing ways of using nanotechnology to establish fibre-based materials as a dominant packaging player.
The issue is likely to become more prominent as the world gets better at recycling materials, and the Nanotechnologies Industry Association (NIA) in Brussels says that companies are already being mindful of existing and future regulation.
NIA director general Dr Steffi Friedrichs says: “We are only just starting to put nanotechnology into production. But no-one is going to put things into production without having thought of the lifecycle. Nanotechnology is about putting much less material into a product and so improving it. It is good business and economic sense to recycle nanomaterials.”
The picture is similar in the US, according to National Institute of Environmental Health Sciences (NIEHS) senior science adviser Dr Sally Tinkle.
“The technology is new enough that we are not yet looking at tyres or car bumpers that have nano elements and which have reached the end of their lives,” she says. “But we’re starting to consider whether it is feasible to recycle nanomaterials. In so many nanoproducts, the material is embedded in the product - at the end of life, does it remain in the matrix or will it break down into tiny compounds?
“We’ve started incorporating materials and product development with end-of-life issues, so that we can look at nanomaterials across the spectrum. We understand the immediacy of these questions and the need to protect public health and the environment. But good science takes time.”
Off the record, advocates of nanotechnology acknowledge that the industry has taken a low-key approach to the issue of recycling. “We have enough problems justifying the use of nanotechnology,” says one senior research scientist for a northern European electronics company. “If we tackle the issue of recycling head on, it will become another argument for critics to seize on.”
Overall, though, there remains a yawning gap in recycling in the nanotechnology sector, according to Markus Widmer, risk manager for nanotechnology at the Innovation Society, a Swiss-based research consultancy involved with the EU-backed 2009 ‘FramingNano’ project, that examined the responsible governance of the industry.
“There are a lot of knowledge gaps, and some fears for a pronounced problem at the end of the lifecycle of nanoproducts,” says Widmer. “The disposal, recycling or incineration of nanomaterials is something that people still do not know very much about.”
One potential area of progress involves scientists scrutinising microemulsion as a means of making it easier to recover, recycle and reuse nanoparticles. Professor Julian Eastoe, from the School of Chemistry at the University of Bristol, has found that a microemulsion of oil and water can help to isolate nanomaterials for recycling. In a test involving nanoparticles of cadmium and zinc, the microemulsion separated into two layers when heated, one containing nanoparticles that could be recovered and the other containing none. But “recovering and recycling nanoparticles is especially difficult because they tend to form complex, hard-to-separate mixtures with other substances,” Professor Eastoe explains.
Dr Freidrichs says the question is how practicable such solutions might prove to be: “There’s a disconnection between what scientists might look to achieve in a laboratory and the need to scale up such a technique in practice.”
Further research may show that some nanomaterials change their structure when exposed at the end of the working life of a product. “Tests have shown that when nanosilver has been washed out from textiles, it tends to forms bigger particles that are not on the nano scale,” adds Widmer.
How well nanoparticles could be extracted from nanomaterials at end of life may influence just how profitable the recycling of such materials may be, he suggests. Extracting intact nanoparticles for recycling purposes from composite materials, such as carbon nanotubes out of a plastic matrix, may prove to be difficult.
“It makes no sense if the end-of-life particles do not have the same nano-specific properties as the original nanoparticles,” he says. “For example, many of the new nano-oxides are not so expensive to produce and only used in small amounts, so I doubt that recycling them will prove to be a prosperous business.”
There is also the question of those recycling employees who will handle such materials. The NIEHS has reported research showing that “when harmless bulk materials are made into ultra-fine particles, they tend to become toxic” and that, generally, “the smaller the particles, the more reactive and toxic are their effects”.
Yet legislation such as REACH and WEEE do not explicitly address the unique issues around nano-technology, Widmer explains.
“As long we don’t know for sure about the effects, you can’t do a proper risk assessment. It seems to be a good idea to have legislation to protect people in the recycling and waste management sector, but you need a clear picture of what the dangerous levels of exposure are to construct sound and practical legislation.”
To understand nanotechnology is to delve into the world of atoms and molecules, to engineering on the tiny scale. The technology took off in the 1980s with the invention of a new generation of microscopes that could see down to the molecular level.
It is already making its presence felt in sectors as diverse as medicine, materials technology and computing - look how small your mobile phone has become.
Applications for nanotechnology include:
- Solar energy collection
- Wound dressings
- Vehicle body and engines
- Fuel additives
- Coatings on toxic substances
- Tags for crime prevention
- Self-cleaning clothes
- Circuits and computers
- Bullet-proof vests
- Textiles incorporating life-signs monitoring and chemical sensing
- Targeted drug delivery
- Stay-clean windows
- Antibacterial work surfaces