Tulane University School of Science and Engineering
Summer MAterials Research @ Tulane (SMART)
Research Experience for Undergraduates
Below we describe sample projects offered by faculty advisors under Materials for the Environment. These representative projects highlight the general interests of the participating faculty, though the specifics may be subject to change.
Materials for the Environment
Oil Dispersants under Extreme Conditions
Hank Ashbaugh, Chemical and Biomolecular Engineering
Application of surfactant dispersant formulations at the source of an oil spill can potentially break up slicks into fine droplets and speed their breakdown. Dispersants applied at the source of deep-sea oil spills, however, face extreme changes in temperature (close to freezing) and pressure (several hundred atmospheres) on the sea floor. These extreme variations challenge the application of dispersants developed at ambient conditions in the lab to real world conditions. Optimal dispersant formulation requires a better understanding of the impact of temperature and pressure on surfactant assembly into the micelles that clean up oil. In this project student participants will use molecular simulations to study the molecular-level interactions between surfactants and water. These simulations in turn will provide deeper insights into the key thermodynamic variables controlling surfactant assembly under extreme conditions (e.g., enthalpy, heat capacity, volume, compressibility, and thermal expansivity) using molecular simulations. Participants will gain experience using molecular simulation packages in a high-performance computing environment and learn how to relate structures generated on the molecular level from computational “experiments” to macroscopic measurements.
Amphiphilic Nanoparticles for Oil Spill Remediation
Scott M. Grayson, Department of Chemistry
Oil spills are typically remediated by applying small amphiphlic molecule dispersants which can self-assemble with the oil to form metastable emulsions. These emulsions are more rapidly dispersed than the oil alone, reducing the local concentration (and therefore toxicity) as well as encouraging the natural bioremediation via indigenous microbes. Although such small amphiphiles can form stable emulsions in closed systems, they can be susceptible to disruption and release of the oil when diluted in large volumes of water, as found in most marine spills. Our laboratory is exploring the use of nanoparticle-based dispersants which are designed to maintain a micelle-like nanospherical shape regardless of concentration or environmental conditions. As a result, these “nanoparticle micelles” exhibit exceptional stability even under the high dilution observed in open water. Our research focuses both on the synthesis of various nanoparticle micelles as well as their structural characterization and evaluation as dispersants.
Environment: Hybrid Materials for Capture of Dilute Species from Aqueous Mixtures
Daniel Shantz, Chemical and Biomolecular Engineering
The capture of dilute species from aqueous mixtures is a ‘grand challenge’ that has implications in fields as diverse as hydraulic fracturing and biofuel processing. The primary complication is an issue of water management: huge quantities of water containing dilute (< 10%) species must be processed efficiently and economically for the processes to be sustainable and hence ultimately viable. We are exploring selectively functionalized oxide particles as model systems for understanding how to selectively capture low molecular weight alcohols and amphiphilic molecules from dilute aqueous mixtures. The former is a central challenge in many bioprocessing technologies. The latter is rapidly coming to the forefront in the context of hydraulic fracturing, where on the order of 3-5 million gallons of water are needed per well and small quantities (< 5 wt%) of nonionic surfactants are used as part of the ‘fracking fluid’. The ability to selectively remove dilute species from these aqueous mixtures will positively impact these two societally relevant problems in general, but also hold significance more generally for water management strategies. Working with a graduate student, REU participants will synthesis and test some of the hybrid materials described above. Participants will receive direct mentoring and develop skills in organic synthesis, in analytical chemistry tools (fluorescence/UV-Vis, etc.) and in engineering testing such as uptake measurements and the determination of equilibrium isotherms.
Mitigating the Adhesion and Spreading of Oil droplets on Marine Surfaces
Noshir Pesika, Chemical and Biomolecular Engineering
During an off shore oil spill, dispersed oil droplets have the potential to spread on a variety of marine surfaces. Noshir Pesika’s group is to exploring the use of particles in stabilizing dispersed oil droplets sufficiently to minimize their spreading on marine surfaces such as corals, marsh grasses and animal skin or coatings. Specifically, we are using carbon microspheres with a well-defined surface energy, which will pin the particles at a specific location on the interface of a dispersed oil drop. In addition to providing a steric barrier, the particles will retain a thin film of water, which will further stabilize the dispersed oil drop. Participants will synthesize and modify carbon particles of varying sizes and surfaces chemistries, and determine their effectiveness in stabilizing oil in water emulsions. Participants will work closely with graduate students currently working on the project and will gain expertise in nanomaterial synthesis and characterization. Specifically, the students will learn how to use a contact angle goniometer to infer the surface wetting properties, use scanning electron microscopy to image particles, use wet chemistry surface modification techniques to alter the chemistry of the nanoparticles and use spectroscopy techniques (UV-vis, FTIR) to characterize the surface modification.