Dr. Külaots' research team investigates bio-wastes, which clearly pose a risk to the environment if disposed in open dumps. These carbonized biomaterials, with a high network of super-micropores, micropores and mesopores offer great opportunities for use in various environmental applications. Our early results suggest that these bio-waste chars are likely candidates for sorbent materials for few EPA top list pollutants.
Dr. Külaots collaborates with Dr. Suuberg in his research on oil shale byproduct semi-coke, coal combustion and coal byproduct fly ash. The majority of oil shale literature focuses on oil shale retorting processes, quantifying extractable oil, and general characteristics of the oil derived from shale. Only a scant amount of the oil shale literature focuses on the characterization of oil shale semicokes, and even less investigates semicoke organic char. The current widely used technology for oil shale oil retorting process negatively impacts environment, since it produces vast amounts of organic rich oil shale semi-coke. Most of this semi-coke ends up in open dumps, and therefore poses threat to the environment. The organic matter of this semi-coke can be as high as 18 wt-%, and the specific surface area around 550 m2/g. The question is, what can be done with this organic rich semi-coke material besides just blending it with other fuels and feeding it to municipal scale boiler systems? In addition, we are looking into oil shale semi-coke contamination with significant levels of phenols, PAHs, or harmful heavy metals.
Dr. Külaots is also actively involved in graphene project in collaboration with Dr. Robert Hurt. Monolayer graphene with the theoretical surface area of 2600 m2/g, has great potential in the fields of catalysis, separation and gas storage if properly converted into bulk materials. Processing graphene often leads to stacking of layers. As the number of graphene sheets per stack increases and if the interlayer spaces are not accessible, the surface area will drop according to the power law: Area ~ (Number of sheets)-1. The 0.335 nm inter-planar spaces of crystalline graphite are not accessible to N2 at 77K or CO2 at 273K, but the potential accessibility of enlarged spaces in reassembled and deformed graphene, graphene oxide, or pillared materials provide opportunities to create high-area bulk materials. With current graphene manufacturing technology it is hard to believe that graphene will be viable candidate as sorbent material any time soon, but it certainly shows promise to be used in gas storage systems if its sheets are pillared.