Metal waste turned into versatile aerogels in eco-friendly way
Aerogel's are extremely light and porous materials with wide-ranging potential, and mechanical engineers at the National University of Singapore (NUS) are getting pretty good at making them out of all kinds of waste products. Previously, this has included scrapped car tires, plastic bottles and even pineapple leaves, and now the team is showing off a new version that is produced via an environmentally-friendly method of upcycling metal waste.
For their latest eco-friendly advanced upcycled material, the NUS scientists have taken aim at the environmental issues associated with recycling metal waste, which can require a lot of energy and create harmful byproducts such as ammonia and methane.
Their novel process begins with metal waste, either aluminum or magnesium, that is ground down into a powder and combined with chemical crosslinkers. This material is then heated in an oven before being frozen and freeze-dried. This whole process takes one to three days and is able to transform the powdered metal waste into an aerogel. This process is low energy and low cost, resulting in an aerogel that is around half the price of a commercially available silica aerogel. It also produces no hazardous waste and can be applied to all types of metal waste through slight variations of the technique.
The researchers imagine a range of uses for their metal-based aerogels, which, like regular aerogels, are ultra light, highly absorbent and have supreme thermal and sound insulation. They can also be treated with a chemical coating to give them other properties, such as becoming water- or fire-resistant. Using them in construction is one possibility.
“Our aluminium aerogel is 30 times lighter and insulates heat 21 times better than conventional concrete," says Associate Professor Duong Hai-Minh, who led the research team. "When optical fibers are added during the mixing stage, we can create translucent aluminum aerogels which, as building materials, can improve natural lighting, reduce energy consumption for lighting and illuminate dark or windowless areas. Translucent concrete can also be used to construct sidewalks and speed bumps that light up at night to improve safety for pedestrians and road traffic."
The scientists also see potential in biomedical applications, where aluminum aerogels could act as a kind of anchor for cell cultivation. In early experiments on stem cells, 12 days of incubation led to a yield of 70 percent, which the team describes as the first successful demonstration of using aerogels to grow cells.
"This is an exciting development that could open doors to a wider use of aerogels for non-conventional applications such as testing drugs and cosmetics, vaccine development and tissue engineering,” Duong explains.
The team is currently working with industry partners to develop their aerogel for these purposes and to commercialize the technology behind its production. They'd also like to develop versions that can tolerate extremely high temperatures, for applications such as the military.
The research was published in the Journal of Material Cycles and Waste Management.
Source: National University Singapore