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Abstract: Photocatalytic ozonation process using TiO2 photocatalyst (O3/TiO2/UV – PH-OZ) conducted in acidic water environment often leads to synergistic effect in terms of decomposition and mineralization of aqueous organic contaminants, which makes the process suitable for waste water treatment or pretreatment of drinking water. [1,2] The synergism is among other factors (pH, O3 dose, T,…) greatly influenced by photocatalyst physicochemical properties and pollutant type. In the first part of the study, five different commercial TiO2 photocatalysts (P25, PC500, PC100, PC10 and JRC-TiO-6) were used in O2/TiO2/UV, O3/TiO2 and O3/TiO2/UV advanced oxidation systems for degradation of two pollutants (dichloroacetic acid - DCAA and thiacloprid – neonicotinoid pesticide), simultaneously present in water solution. [3] Results of PH-OZ (O3/TiO2/UV) experiments showed that in contrast to DCAA which adsorbs on TiO2 surface, synergistic effect is much more expressed in the case of thiacloprid which doesn’t adsorb. The influence of BET surface area of the photocatalyst and its dispersivity will be discussed. In the second part of this study, selected catalysts were immobilized on a proper support to avoid post-filtration step in the process of greywater treatment. A good adhesion of a catalyst on various supports was successfully achieved by immobilization of commercial TiO2 powders (P25, P90, PC500) with the help of a sol-gel silica-titania binder [4]. For the purpose of simulated greywater treatment, special compact reactor was designed and developed, utilizing Al2O3 porous reticulated monolith foams as TiO2 carriers and UVA-lamps inside (Fig. 1). [5] With degradation of LAS+PBIS and Reactive blue 19 (RB 19) as representatives of surfactants and textile dyes respectively, commonly found in household greywater, and phenol as trace contaminant, an evaluation of PH-OZ and photocatalytic oxidation has been performed (an example in Fig. 2). Synergistic effect of PH-OZ was generally much more expressed in mineralization reactions, showing TOC half lives of less than one hour for the mixture of pollutants in compact reactor. [5] Due to its superior cleaning capacity, PH-OZ process employing efficient photocatalysts is suitable for treating wastewaters also with higher loading of organic pollutants. 1. U. Černigoj, U.Lavrenčič Štangar, J. Jirkovsky, J. Hazard. Mater. (2010) 177:399–406. 2. U. Černigoj, U.Lavrenčič Štangar, P. Trebše, Appl. Catal. B Environ. (2007) 75:229–238. 3. M. Kete, U. Černigoj, U. Lavrenčič Štangar: Photocatalytic ozonation – study of reaction parameters and mechanism, article under submission 4. M. Kete, E. Pavlica, F. Fresno, G. Bratina, U. Lavrenčič Štangar, Environ. Sci. Pollut. Res. (2014) 21:11238–11249. 5. M. Kete: Towards efficient removal of contaminants in water from household appliances by TiO2-photocatalysis: design, optimization and performance studies of the photoreactor with immobilized catalysts, Doctoral dissertation (2015), University of Nova Gorica, Nova Gorica.
Found in: ključnih besedah
Summary of found: ...1). [5] With degradation of LAS+PBIS and Reactive blue 19 (RB 19) as representatives of...
Keywords: photocatalysis, ozonation, TiO2, dichloroacetic acid, thiacloprid, mechanisms, LAS+PBIS, Reactive blue 19, phenol
Published: 21.07.2016; Views: 6026; Downloads: 0
Fulltext (4,10 MB)

Found in: ključnih besedah
Summary of found: ...ctroscopy, Dye remediation, Photothermal technique, Photocatalytic degradation, Reactive Blue 19, TiO2 modification...
Keywords: Thermal lens spectrometry, Photothermal beam deflection spectroscopy, Dye remediation, Photothermal technique, Photocatalytic degradation, Reactive Blue 19, TiO2 modification
Published: 09.11.2018; Views: 2894; Downloads: 0
Fulltext (208,76 KB)

Abstract: In recent years a classification of materials based on their topological order gained popularity due to the discovery of materials with special topological character – topological insulators (TI). TI have different band structure than regular insulators or conductors. They are characterized by a band gap in the bulk of the material, but at the surface they possess conductive topological surface states (TSS) that cross the Fermi level. TSS are a consequence of the non-trivial bulk band structure and have properties that differ from ordinary surface states. They are robust toward contamination and deformation of the surface. Additionally, they are also spin polarized, which means that an electron spin is locked to a crystal momentum and, therefore, backscattering during transport is suppressed [1]. Due to their specific properties the TI could be used in fields of spintronics, quantum computing and catalysis [2]. The investigation of the interfaces between metals and the TI has not been given much attention even though its characterization is interesting from fundamental physics and applicative point of view. (In)stability of the contacts with metal electrodes, in a form of a chemical reaction or diffusion, has to be taken into account since it can affect the transport properties of the material or increase the contact resistance. Our research is dedicated to the study of the metal/TI interfaces, in particular to Bi2Se3 with deposited metals that are relevant for electrical contacts (Au, Ag, Pt, Cr, Ti). The thermal and chemical stability of the interfaces are of fundamental importance for understanding the contact behavior, therefore, we focused our work to the characterization of these properties. The metal/TI interfaces are investigated mainly with an electron microscopy (SEM, TEM, STM), EDX microanalysis and XRD. Our previous studies showed that the interface between Bi2Se3, and Ag deposited either chemically or from a vapor phase, results in the formation of new phases already at room temperature [3]. On the contrary, Au deposited on the Bi2Se3 surface shows very limited reactivity and is stable at RT, but diffusion and coalescence of the metal are observed starting from 100 °C [4]. In this contribution, we will present further characterization on the evolution of the Ag/Bi2Se3 and Au/Bi2Se3 interfaces, show preliminary results about recently investigated systems (Pt/Bi2Se3, Ti/Bi2Se3) and compare the thermal and chemical stability of the systems under investigation.
Found in: ključnih besedah
Summary of found: ...ctroscopy, dye remediation, photothermal technique, photocatalytic degradation, reactive blue 19, TiO2 modification...
Keywords: thermal lens spectrometry, photothermal beam deflection spectroscopy, dye remediation, photothermal technique, photocatalytic degradation, reactive blue 19, TiO2 modification
Published: 20.08.2021; Views: 1462; Downloads: 0
Fulltext (100,42 KB)