Photocatalytic degradation of acetaminophen in water via ultraviolet light and titanium dioxide thin films part II: chemical and kinetic aspects

Among the large family of emergent pharmaceutical contaminants, we find acetaminophen (ACE) that critically needs to be removed from wastewater. Advanced Oxidation Process (AOP) have proven effective in the degradation of large molecular contaminants from water. To the best of our knowledge this is the first study reported on the degradation of ACE based on immobilized TiO2 thin films. In an effort to increase the understanding of the efficiency of the degradation process, an in-depth investigation of the effects of the structure, i.e., coating layers and the amount of surface, i.e., number of coated slides used, is needed. Transparent, anatase-form TiO2 thin films were prepared via the sol-gel method (Rawal, S., S. Buer, J. R. Sanders, and P. E. Arce. 2021. “Photocatalytic Degradation of Acetaminophen from Water Solutions Via Thin Films. Part I: Synthesis and Characterization of TiO2 Thin Films.” International Journal of Reactor Engineering [Accepted]) and deposited onto glass microscope slides using a novel spraying technique, with coatings ranging from one to 10 layers. This contribution summarizes the effect of several key factors including initial concentration of the ACE, the number of coating layers (6, 8, and 10) on the glass slides and the number (4 and 6) of slides on the degradation levels for three selected media, e.g., acid, neutral and base. Comparisons studies, supported by statistical analysis between two different sets (4 and 6) of slides with discussion of potential physical-chemical reasons behind the behaviors are reported. Finally, global, first order kinetic rate constants are also reported for the different conditions used in the investigation. Although further research would be needed, in general the results are promising for the potential degradation of ACE in continuous flow systems by using immobilized TiO2 on surfaces as thin films.

Photocatalytic degradation of acetaminophen from water solutions via thin films part I: preparation, characteriation, and analysis of titanium dioxide thin films

The utilization of titanium dioxide (TiO2) photocatalysis for water and air purification is a frequently used method due to TiO2 having properties making it chemically inert, highly cost-effective, abundant, non-toxic, and environmentally-friendly. In an effort to increase the efficiency of the degradation process, an in-depth understanding of the effects of the structure and number of thin film coatings is needed. Transparent, anatase-form titanium dioxide thin films were prepared via the sol-gel method and deposited onto microscopic glass slides using a novel spraying technique, with coatings ranging from 1 to 10. Characterization of the TiO2 thin film coated slides was performed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The contribution shows that the coating technique is efficient in covering important areas of the surface and that it is suitable for a multiple coating layers thin film. The SEM imagines show that the surface of the slides increase coverage as the number of layers increases. This is potentially suitable for a mechanized spraying approach to upscaling the production of thin films for advanced oxidation applications.

Influence of plasmon resonance on the luminescence of titanium dioxide thin films doped with rare earth ions

In this work the study of the optical properties of europium doped titanium dioxide thin films (TiO2:Eu) enhanced by gold plasmonic nanostructures are presented. Plasmonic platforms were manufactured by thermal annealing of thin film of Au, deposited on a Corning glass substrate. As a result of thermal treatment, gold spherical nanostructures with average dimensions of 50 nm were obtained. Luminescent TiO2:Eu film was deposited by RF magnetron sputtering method, from mosaic target. Morphology of gold nanostructures was investigated by SEM and TEM microscopes, while composition of oxides film was analysed by XPS methods. Luminescence properties were studied on the basis of excitation and emission spectra. Experiments have shown that such structures exhibit interesting luminescent properties and could be potential candidates for optoelectronics applications.