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TITLE:  Recycling Enrironmental Wastes into High-Value Materials for Novel Engineering Applications.

HAI M. DUONG,  Associate Professor, Department of Mechanical Engineering 

National University of Singapore (NUS), Singapore.

Recycling environmental waste can avoid many hazardous environmental scenarios and save our resources. Our aerogel technology can recycle various environmental wastes to high-value engineering materials. Common paper, fabric and plastic wastes are selected to develop the lightest aerogel materials for novel applications such as oil-spill cleaning, heat and sound insulation, winter garment materials, packaging, CO2 filtering, personal care and medical products.

Using an cost-effective and green sol gel technique with no toxic solvents and cross-linkers, recycled fibres from the wastes are converted into ultralight porous, biodegradable and non-toxic aerogels. Our method uses 70% less energy and results in reduced polluting emissions into the air and water. It is also faster as the entire process takes only 8 hrs to 1 day. This is 20 times faster than current commercial processes. Thus we can significantly reduce manufacturing and equipment costs. The manufacturing cost of an A4-size aerogel sheet is approx. US$0.5-2.0, much cheaper than commercial Aspen aerogels for heat insulation or commercial sorbents for oil spill cleaning. The developed aerogels are highly compressible for the first time; hence storage and transportation costs are greatly reduced. The compressed aerogels can very quickly recover 97 % of their original size when placed in water. The used aerogels can be recycled so no waste is disposed to the environment.

The above highly compressible, cost-effective and biocompatible hybrid aerogel pellets can be easy integrated into a clinical syringe to be used as a haemorrhage control device. Each compressed aerogel pallet can expand in volume to 16 times its size in 4.5 seconds, 3 times faster than commercial haemorrhage devices, while retaining their structural integrity. The fast aerogel expansion also exerts high pressure to stop the wound bleeding within 5 seconds.

The aerogel surface can be functionalized effectively by the nanocoating method at low temperature for the above-mentioned applications. For example, the MTMS-coated aerogel can absorb oil 99 times of their dry weight and 4 times as effective as commercial oil sorbents. They can be reused several times and can be recovered by squeezing out over 99 % of oil absorbed. At the end of their useful life, the used aerogel can be safely ground into fine particles and discarded. This potential market has been estimated at US$143.5 billion. With amine group coating, the amine-coated aerogels can absorb large amounts of CO2 from air. Also with fire retardant coating, the aerogels can withstand an ambient temperature of 600-620 oC and prevent fire from spreading inside buildings. The potential market of thermal insulation is US$3.3 billion globally. Beside the heat and sound insulation of the buildings, we also developed successfully a lightweight thermal jacket using aerogels, to insulate water bottles, to maintain the temperature of ice slurry at -1oC for 4 hours. A thermal jacket consists of an aerogel layer embedded within common fabrics to provide effective heat insulation. The aerogel-insulated bottle offers better heat insulation performance than commercial FLOE bottles and is highly comparable to that of vacuum flasks, but at a fraction of the cost.

Short bio of Associate professor of Hai M. Duong

Dr. Hai M. Duong received his Ph.D. in Chemical Engineering at Melbourne University in 2004. Since then, he has expanded his research interests in science and applications of carbon-based nanomaterials through experiments and computational modelling. He was awarded four postdoctoral fellowships at world-class laboratories: University of Oklahoma, USA; University of Tokyo, Japan; Massachusette Institute of Techlogy (MIT), USA and University of Cambridge, UK. Currently, as an Assistant Professor of at National University of Singapore (NUS), he has awarded 4 global innovational awards and his research interests include a number of emerging fields such as carbon nanotubes (CNTs), aerogels and their applications for aerospace structures, energy devices, environmental treatment, and thermal transport phenomena in small-scale of biological systems. He has 13 patents, published 12 book chapters, 150+ journal papers and conference proceedings, gave several keynotes and invited talks.  Dr. Duong is also the key member of Functional Material Society and the technical committee on nanotechnology in Singapore and the editorial member of International Journal of Aeronautical Science and Aerospace Research (IJASAR).