A Robust Process for Effective Carbon Capture (by Parviz Soroushian)

A complete replacement of fossil fuels by renewable sources of energy is not feasible in the short term. Therefore, there is a need to equip fossil fuel power plants with CO₂ capture and sequestration (CCS) capabilities in order to prevent the projected 2°C global warming by 2100. Carbon capture and sequestration would allow for continued use of fossil fuel until a deeper penetration of renewable energy sources into the grid is realized in an orderly fashion. Widespread adoption of CCS technologies would benefit from the availability of processes that lower the cost. Developments in advanced CCS materials and processes are needed in order to achieve this goal. One option is to develop a robust, economical and efficient CCS process based upon the principles of mechanochemistry.

The mechanochemical CCS process will take place in ambient condition within an energy-efficient mill incorporating a nearly dry inorganic sorbent. In the CO₂ sorption step (A), the input of mechanical energy will disturb the structure of the solid sorbent, and will drive CO₂ dissolution and deep diffusion of carbonate anions. This process offers favorable kinetics comparable to the dissolution of carbon dioxide in melts at magmatic temperatures and pressures. The disturbed structure of the sorbent and the dissolved nature of the captured CO₂ enable desorption within the same (mill) chamber at a moderately elevated temperature produced efficiently via microwave irradiation (B); rotation of the mill at a low speed benefits the uniformity of microwave exposure. The mild desorption conditions benefit the stability of the sorbent under repeated sorption-desorption cycles. The mechanochemical CCS process is robust, and can be tailored to accommodate different solid sorbents and the combustion emissions of different fossil fuels. Scale-up of the process benefits the mechanochemical effects by raising the intensity of energy input. 

Building and Furnishing Materials for Improved Indoor Air Quality

 

People spend approximately 90% of their time indoors at homes, public buildings and offices where concentrations of many pollutants, including volatile organic compounds (VOCs), are frequently higher than the outdoor urban air. Adverse health effects can result from the buildup of several VOCs in the indoor air, including formaldehyde, benzene, toluene and xylene. Building materials and furnishings are sine sources of VOC emissions. Development of commercially viable building and furnishing materials with reduced emissions would allow for implementing more stringent codes that enable improvement of the indoor air quality.

Reconstituted (engineered) wood products have emerged in recent decades as popular building and furnishing materials. They are composed of wooden elements of various size and shape, bonded by a synthetic resin. Examples of reconstituted wood products are particleboard, medium density fiberboard (MDF) and hardwood plywood (made commonly with urea-formaldehyde resins), and oriented strandboard and softwood plywood (made with phenol-formaldehyde resins). Reconstituted wood products constitute the majority of indoor surfaces (building products, cabinets and furniture). They can emit a variety of VOCs into the indoor air environment; examples include formaldehyde, acetone, hexanal, propanol, butanone, benzene and benzadehyde. Synthetic resins are the primary sources of any formaldehyde emission from reconstituted wood products.

Some adverse effects of reconstituted wood products on the indoor air quality have created a need for development of low-emission reconstituted wood products, and for development of building codes that encourage their broad adoption. This need can be addressed in a fundamental way through development of lower-emission binders that meet relevant performance, cost and sustainability requirements. Development of refined inorganic polymer binders and compatible processing techniques could be a viable approach to addressing the need for reconstituted wood products that are friendlier to the indoor air quality.

The Amazing Nacre (Mother of Pearl)

 

Nacre, also known as mother of pearl, is an organic–inorganic composite material produced by some molluscs as an inner shell layer. It comprises 95% calcium carbonate (aragonite) which, due to its layered microstructure, yields tensile strength, toughness and ductility levels as well as barrier and durability characteristics that far exceed those of monolithic aragonite or artificial inorganic materials such as concrete.

The superior engineering properties of nacre result from its controlled microstructure fored during a biomineralization process. This process involves controlled through-solution crystallization of amorphous materials (mostly calcium carbonate) to form intricate microstructures tailored towards serving structural, protective and other purposes.

Can we learn from biomineralization of nacre to produce improved material for construction of longer-lasting, safer and more sustainable infrastructure systems?

Morphing Aircraft: The Need for Flexible Skin

 

The morphing aircraft attempts to break out of the confines of rigid structures with the intention of creating vehicles with multiple functional equilibria. The morphing aircraft is a multirole platform that changes its state substantially to adapt to changing operation environments, and is viewed as part of a revolutionary transformation from large, expensive piloted aircraft to smaller, autonomous types with combined roles and increased functionality. 

Flexible skins constitute an enabling technology for morphing aircraft. The skin must be able to handle large in-plane deformations and out-of-plane aerodynamic loads while simultaneously carrying some shear loads. There are numerous design concepts that can be used for morphing aircraft, but most designs cannot effectively integrate skins. Elastomers constitute a promising group of materials for flexible skins; they are capable of elastically deforming by very large amounts without permanent changes in shape. The occasional cross-links within elastomers define an original shape which will be restored upon unloading.

Since elastomers are generally insulating, elastomeric skins can become charged in service; they could then behave as a capacitor and discharge in a single event causing considerable damage to the surrounding materials and the electronics on the vehicle. To mitigate electrostatic charge buildup, the surface resistivity of the skin should be lowered below a threshold level, which should be retained even under large elastomeric deformations. The conductivity of the elastomeric skin would also provide a level of protection against lightning strike.