Events

Solid oxide electrolysis cell (SOEC) is a promising technology for CO₂ electrolysis and subsequent conversion to useful chemicals. This thesis combines the experimental development of new cathode materials with system-level simulation to enhance the performance of SOECs for CO2 electrolysis and assess their applicability for fuel production. There are two components to the work: (1) proposing nanoparticle decorated perovskites cathode material and (2) integration of DAC, SOEC and synfuel production and asses its performance with techno-economic and environmental analysis.

In the experimental section, the focus was on the cathode material of the SOEC since it is the limiting factor for CO₂ electrolysis.

Sustainable Agrochemical Delivery Systems Based on Cellulose Nanocrystals and Chitosan by Gaili Cao

The representative elementary volume (REV) is a fundamental concept in the study of porous media, describing the minimum volume at which a material property can be considered statistically representative of the whole.

Determining an REV is essential for linking pore-scale measurements to continuum-scale models used in engineering and geoscience. The results of this work demonstrate that REVs can be identified from relatively small fractions of the total image volume given that certain conditions are met, offering a balance between accuracy and computational efficiency.

Biological systems are essential in biopharmaceuticals, where rising demand requires efficient bioreactor operation. Scaling from lab to industry is limited by gradients from poor mixing, reducing yields through cell stress and adaptation. This work quantified dissolved oxygen, pH, and kLa gradients in a 20 L bioreactor. While cell density and metabolite gradients were inconclusive, metabolic responses were modeled with modified Monod kinetics, which adapted well to differing conditions.

Thesis Title: Transport and Irreversible Retention of Hydrophobic Nanoparticles by Fluid-Fluid and Fluid-Solid Interfaces in Porous Media

Abstract:

Hydrophobic nanoparticle (NP) transport in porous media has implications for aquifer transport and retention of a wide range of contaminants that infiltrate water resources and threaten human health as well as aquatic environments. Comprehension of NP transport and interactions with hydrophobic surfaces and interfaces -given their ubiquity in porous aquifers- is essential for groundwater remediation from organic contaminants, toxic engineered NPs, and nanoplastics.

This research investigates the transport and attachment of hydrophobic NPs under varying physicochemical conditions in saturated and unsaturated porous media by integrating experimental observations across multiple scales, theoretical extended-DLVO predictions, and numerical modeling. A non-toxic, negatively-charged, hydrophobic model NP system synthesized from ethyl cellulose (EC), and exhaustively characterized for colloidal stability and interfacial interactions, was employed to systematically explore NP interactions with fluid-fluid and solid-fluid interfaces.

The upscaling capability of an advection-dispersion-retention continuum model was compared vis-à-vis a pore network model of irreversible NP attachment onto fluid interfaces in 3D columns packed with spherical glass beads, showing that the latter captures key pore-scale dynamics such as bypassed interfaces, slow-moving corner flows, and diffusion-dominated retention.

Transport experiments in 2D microfluidic pore networks confirm that the dynamics of NP retention in unsaturated porous media depend not only on the saturation of the non-wetting phase, but also on its connectivity and the accessibility of immobile fluid-fluid interfaces.