The Generation and Transport of Charged Aerosols: Fundamental Study and Applications in Medicine and Energy Conversion
Date of Award
Doctor of Philosophy (PhD)
Charged aerosols have significant implications in the field of functional material synthesis, pharmaceutical coating, and drug delivery. Electrospray systems are an effective methodology for generating highly charged monodispersed droplets in the size range from nanometer to micrometer. The prediction of surface charge, size and morphology of nanoparticles resulting from charged droplets are highly required for the precise control of nanoparticle properties and their effective utilization. However, the evolution of charged droplet is not well understood due to the existence of coulombic fission and ion evaporation processes. Thus, the goal of this dissertation is to elucidate how the precursor properties and operating parameters of the electrospray control the charged droplet evolution and explore high potential of charged aerosols in medicine and energy conversion.First, we develop a general and complete model for charged droplet drying to predict the final size and resultant charge of the particles. The model accounts for solvent evaporation, solute/nanoparticle diffusion, the collision and aggregation of nanoparticles, coulombic fission and ion evaporation processes. The competition among these subprocesses determines the final size and charge. The model equations are cast into nondimensional forms for generalization. The governing dimensionless parameters are derived and their influences on the final particle size and charge are investigated numerically. The most important parameters are the non-dimensional characteristic diffusion time, non-dimensional characteristic coagulation time, non-dimensional flow rate and coulombic fission related loss. An analytical solution is obtained in the case of slow drying. The models developed provide guiding principles to help design the experiments of material synthesis by electrospray. Second, an experimental investigation of synthesis of charged lignin nanoparticles for drug delivery using an electrospray system was systematically performed. The control of size and charge distribution of lignin nanoparticles synthesized in this single-step process by tuning the operation parameters and precursor properties is demonstrated. The generalized theoretical model to predict the size and charge developed in first part is then verified for a variety of experimental conditions. Finally, the formation mechanism of lignin nanoparticles with three different morphologies: solid sphere, hollow sphere, and elliptical solid, was explored. To deliver drugs efficiently to target cells, charged nanoparticles must pass through mucus barrier layers. A data-driven model based on machine learning was then developed to identify key factors governing the diffusion behavior of charged nanoparticle in mucus, and predict the diffusion mode, diffusion coefficient and the penetration efficiency. Third, HKUST-1 (Cu3BTC2, where BTC = 1,3,5-benzenetricarboxylate)/PEDOT (Poly(3,4-ethylenedioxythiophene)) thin film were synthesized in a fast and efficient manner through depositing charged HKUST-1 nanoparticles on PEDOT substrate using the electrospray system. The effects of the precursor concentration, the flow rate and the substrate temperature on the crystallinity and BET surface area of pure HKUST-1 thin film were systematically investigated. The electrospray-deposited HKUST-1 thin film demonstrated uniform thickness, good crystallinity, and large surface area. Then, HKUST-1/PEDOT thin film composites were utilized as photocatalyst for CO2 photoreduction, showing a great improvement in catalysis efficiency, as compared with pure PEDOT. Last, we explored the application of neutral aerosols in health and energy conversion. The numerical simulation of the interaction between air puff, tear film and cornea were performed to elucidate the tear film aerosolization mechanism during Non-Contact Tonometer, which provides insights into avoiding the transmission of virus existing in tears. At the same time, we demonstrate the rapid synthesis of the multispecies compound KBaTeBiO6 with extremely high purity and controllable size through a single-step furnace aerosol reactor (FuAR) process. The as-synthesized KBaTeBiO6 nanoparticles exhibited an excellent photocatalytic performance for CO2 photoreduction under UV-light.
Rajan Chakrabarty, Rohan Mishra, Vijay Ramani, Grigoriy Yablonsky,
Available for download on Monday, August 26, 2024
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