This energy related project stems from a recent paradigm-changing proof-of-concept result reported by the research group of Daniel Resasco at the University of Oklahoma [Science 327 (2010) 68]. The experimental results showed that it is possible to perform in-situ upgrade of bio-oil (the pyrolisis product of lignocellulosic biomass) when solid particles are used to both stabilize water-in-oil emulsions and support heterogeneous catalysts. The solid particles used were hybrid materials obtained by fusing silica particles on carbon nanotubes. To generalize this proof of concept to large-scale industrial applications it is necessary to design simpler and cheaper particles that stabilize oil-in-water emulsions and support the catalysts. It is necessary to understand how the molecular level features characterizing the solid particles determine macroscopic properties such as drop size and shape, as well as the mechanism of droplets coalescence. It is also desirable that the particles can be recovered after the bio-oil upgrade is complete. It is well known that solid particles adsorb at water-oil interfaces to reduce the contact area between the two immiscible phases. Stable emulsions are obtained when the particles strongly adsorb at the interfaces. It is plausible that by adding appropriate surface-active compounds the particles can be easily released from the interfaces. Once in the continuous phase, the particles tend to agglomerate, facilitating their recovery. Quantification of these qualitative expectations will transform the bio-energy field. Experimental evidence shows that particles behavior at interfaces strongly depends on the particle density (a signature of emergent behavior). In order to rationalize these experimental observations and to enable the potentially transformative implementation of in-situ bio-oil upgrade at the industrial scale, a multi-scale thermodynamic model is required to link molecular-level properties to macroscopic observations.
Intellectual Merit:
The scientific goal of this proposal consists in the development of a multi-scale theoretical model, based on simulations at all-atom and coarse grained levels, to elucidate the emergent behavior of nanoparticles adsorbed at water decane interfaces. Nanoparticles of interest include silica (spherical and discoid) and MgO (cubic) ones. To stabilize water-oil emulsions, these particles are functionalized to become partially hydrophobic. Nanoparticles with uniform surface properties, as well as Janus nanoparticles in which part of the surface is hydrophobic and part of it is hydrophilic will be studied.
Broader impacts: The theoretical model derived within this proposal will allow us to better understand and predict the properties of solid particle stabilized emulsions. These emulsions are finding technological applications in the manufacture of new materials, in the stabilization of polymeric foams, and also in food science. Understanding the packing of particles at interfaces, and the driving forces responsible for the appearance of exotic two-dimensional phases is also of interest for the manufacture of polymeric nanocomposite materials, which are being developed for, among other applications, harvesting solar energy.
Outreach and Education:
The project will involve one graduate student and three undergraduate researchers. Under represented minorities, especially females and Native Americans, will participate in our activities. Connections with colleges with significant Native American student population (specifically Northeastern State University in Tahlequah, OK) have been established. The research activities proposed herein will contribute to attract high-school students towards STEM careers, especially in Oklahoma, a state whose economy has traditionally relied on energy production and utilization. Towards this goal, the collaboration of Mr. David Askey, secondary science teacher at Norman High School, has been secured. Funding of this project allows the investigators to continue delivering seminars at Norman High School once a year.
