Our research in EPTL focuses primarily on nanoparticles made by gas-phase processes such as flames and plasma reactors, their functional properties, applications in novel energy storage and sensing technologies as well as their impact on the environment.
Nanoparticles made by gas-phase synthesis (flames) are abundant in our everyday lives. For example, Carbon Black, the largest flame-made nanomaterial by value and volume (a $15 B industry), is a major component in tires, inks, and batteries. On the other hand, soot – a material very similar to carbon black – is a major air pollutant. Other examples of flame made nanoparticles that are produced in tons/hour capacities include filamentary titania (TiO2), silica (SiO2), and nickel (Ni) with applications in pigments, cosmetic products, and batteries.
Detailed knowledge or control of nanoparticle size distribution, morphology, chemical composition, and optical properties are needed to quantify their health and environmental impact or to meet product quality requirements. For example, most of Carbon Black is currently made by rich combustion of heavy fuel oil, a century-old process that emits a significant amount of CO2 into the atmosphere. Alternative plasma conversion processes are available for large scale decarbonization of hydrocarbons to simultaneously make Carbon Black and Hydrogen. However, they are not used due to a lack of process control and product selectivity. What makes nanoparticle engineering exciting is state-of-the-art diagnostics techniques and computational tools that enable a detailed understanding of the complex relationship between process parameters, particle characteristics, and material performance that creates exciting opportunities to design new processes for selective synthesis of these particles for new applications and novel technologies.
- Gas-phase synthesis of nanoparticles
- Flame Spray Pyrolysis for large scale nanoparticle synthesis
- Soot/carbon black formation during combustion/pyrolysis
- Optical properties of soot nanoparticles
- Impact of soot on the environment and global warming
- Measuring and quantifying soot emissions
Current Research Projects:
- Multi-scale design of nanoparticle synthesis in the gas phase: Nanoparticles made by gas-phase processes have significant scientific and commercial applications. For example, flame made nanoparticles with controlled size, optical properties, and surface functionalities are being developed for photothermal cancer treatment and targeted drug delivery. Also, carbon black, i.e. the largest flame made nanoparticle by value and volume (a $ 15 B industry) is used as a reinforcement agent for rubber or conductive filler in batteries. On the other hand, soot, a material very similar to carbon black is an air pollutant and the second contributor to global warming. The functional properties or the environmental impact of these nanoparticles depend on their morphology, chemical composition, and optical properties. The aim of this project is to develop advanced multiscale modeling tools to understand the impact of process conditions, i.e. high-temperature particle residence time, on particle morphology, size distribution, and optical properties. In this project, molecular dynamics (MD) simulations will be used to obtain critical parameters on the interaction of atoms that are needed for mesoscale simulations of nanoparticle interactions. We use Discrete Element Modelling (DEM) to track the formation of fractal-like nanoparticle agglomerates with detailed morphology. From such simulations, power laws describing agglomerate morphology will be used in CFD simulations in order to reduce computational cost.
- Optical properties of carbonaceous nanoparticles: Soot is the third contributor to global warming after carbon dioxide and methane and raises the atmospheric temperature by 0.57 ± 0.46 oC. However, unlike CO2 that could last up to 1000 years in the atmosphere, soot is a short-lived pollutant with a lifetime of up to 7 days. Thus, mitigating soot emissions could have an immediate impact on our climate. However, soot optical properties are not known well, causing large uncertainties in estimates of the impact of soot on global warming. Such uncertainties impede developing effective policies and accurate models to control soot emissions and predict their impact on the environment, respectively. Accurate soot optical properties are also needed for developing sensitive and selective fire detectors that can distinguish soot from nuisance aerosol to avoid false alarms. This project focuses on accurate measurement of soot optical properties such as its absorption and scattering cross-sections and links them to its morphology and chemical composition. We then use Discrete Dipole Approximation coupled with DEM simulations to predict the optical properties of soot nanoparticles with realistic morphologies.
- Materials for thermal energy storage: Novel Thermal energy storage is a crucial part of the development of solar-thermal renewable energy conversion systems. However, storing thermal energy is expensive, cannot last efficiently for longer than a day, and should be used locally. Using thermal energy for the synthesis of fuels is an attractive alternative. With chemical energy storage, thermal losses are mitigated and the synthesized fuel could be stored and transported to regions where energy is needed. This project focuses on developing processes in which solar thermal energy is used for the synthesis of energetic particles that could later be oxidized to harness their chemical energy.