Doctor of Philosophy
Chemical and Biochemical Engineering
Hugo de Lasa
The high VOC emissions from anthropogenic sources are detrimental to both the environment and humans, contributing with ground-level ozone and particle matter formation. Heterogeneous photocatalysis provides significant potential for VOC degradation. However, the approaches to be used for photocatalyst immobilization in scaled and highly efficient photoreactors are still not well established. Furthermore, there is a lack of reported photonic efficiencies and a shortage of required methods to establish these efficiencies.
To address these issues, this PhD Dissertation reports the study of photonic efficiencies, TiO2 immobilization on a stainless steel mesh and kinetic models in a scaled-up Photo-CREC-Air Reactor. Acetone and acetaldehyde are considered with a 25-320 initial concentration range. The irradiation field is experimentally evaluated in order to estimate the photon absorption on the TiO2 film through macroscopic balances. Quantum Yields (QYs) and Photochemical Thermodynamic Efficiency Factors (PTEFs) are also established.
TiO2 coatings are prepared using two methods: an Air Assisted Spray with an Automatized Spinning Coating (TiO2-AAS-ASC) and a Spread Coating (TiO2-SCM). TiO2-AAS-ASC shows a more efficient use of the photocatalyst than the TiO2-SCM, and also displays homogeneity, limited particle agglomeration and stability under flow. Moreover, the TiO2-AAS-ASC shows a high degree of photonic energy utilization.
A series-parallel Langmuir-Hinshelwood based kinetic model describes the photodegradation of acetone and acetaldehyde data well with a 0.97-0.98 range correlation coefficient.
It is believed that altogether the approach reported in the present PhD Dissertation contributes to clarify key engineering issues of significant value for the scale-up of photocatalytic reactors for air treatment.
Lugo Vega, Cristina S., "Evaluation of VOC Degradation in Photo-Catalytic Air Reactors: TiO2 Immobilization, Energy Efficiency and Kinetic Modeling" (2016). Electronic Thesis and Dissertation Repository. 4019.