Collaborative Research: Understanding the effect of transient interfacial dynamics in the transport and deposition of particles in the vadose zone
The transport of small suspended particles, referred to as colloidal particles, in geological media has been the subject of numerous studies, due in part to its importance in contaminant spreading and water purification. The vadose zone, the upper levels of the soil column, is the entry point for the replenishment of groundwater reservoirs and, therefore, the transport and fate of particulates is key to the sustainability of water resources. Particulates containing contaminants, ranging from pathogenic microbes to the increasing number of nanoparticles used in industrial applications, can pollute groundwater reservoirs. In addition, it has been shown that colloidal particles can facilitate the transport of molecular contaminants. Unfortunately, the development of predictive models for the transport and fate of colloidal particles in the vadose zone has proven especially elusive. A better understanding of the mechanisms driving the transport of particulates in unsaturated porous media could lead to new paradigms in the design of water purification processes, the management of contamination risk, the development of remediation strategies, and would facilitate the recovery and recycling of technological nanomaterials. The impact of this work lies in both education and outreach, public health, as well as on its technologically enabling capabilities. Training will be provided to graduate students, undergraduates, and high school students in an interdisciplinary environment that includes a strong exposure to the fields of materials and interfacial science as well as transport and modeling. The investigators educational philosophy is designed to foster a true passion for science in students by giving them opportunities to actively produce scientific material, rather than acting as passive consumers. Outreach and educational efforts by the investigators will include course development, and the ongoing participation of undergraduates and high school students to the research activities. The investigators groups will also adopt an after-school classroom for a year (visiting the classroom weekly) in which students, under the guidance of a trained facilitator, will engage in hands-on STEM activities in the area of sustainability of water resources. In the lab, undergraduates and high school students are encouraged to present their findings within the group and externally, including authorship in peer-reviewed scientific publications.
The technical portion of the proposed work lies in the broad scientific, technological, and economical importance of remediation of contaminants from groundwater, especially as the resources for potable water are becoming scarcer, the use of synthetic particulate and nanomaterials increases, and the cost of energy is skyrocketing. The transformative nature of the proposed work lies in providing a particle-level understanding of the role of non-equilibrium hydrodynamic and chemical transients on the attachment/detachment of particles from air-water (-solid) interfaces by the integration of state-of-the-art experimental and simulation tools. The results from the proposed work will also be important in other scientific areas such as water filtration, oil recovery, fouling in microfluidic devices, and clogging. Therefore, there is an important scientific and engineering rationale in understanding the mechanisms for particles adsorption and desorption from an air-water (-solid) interface during transient conditions. The design of simple and versatile experiments to address these issues will lead to an ideal platform to study particle deposition in unsaturated porous media. In addition, tools that will be developed for this work will allow, in the future, to study the deposition of more complex colloids such as bacteria, viruses, or minerals of various shapes and propensity to adsorb at fluid interfaces.
