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12.
Determination of iron in natural waters using DGT technique coupled to phototermal beam deflection spectroscopy
Hanna Budasheva, Arne Bratkič, Dorota Korte, Mladen Franko, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...Beam deflection spectroscopy, diffusive gradients in thin-films, iron species, photothermal techniques, natural waters....
Ključne besede: Beam deflection spectroscopy, diffusive gradients in thin-films, iron species, photothermal techniques, natural waters.
Objavljeno: 09.11.2018; Ogledov: 898; Prenosov: 0
.pdf Polno besedilo (40,53 KB)

13.
Determination of bioavailable Fe redox fractions of sediment pore waters by DGT passive sampling and BDS detection
Mladen Franko, Arne Bratkič, Dorota Korte, Hanna Budasheva, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: The bioavailability and toxicity of contaminants in sediments to benthic organisms depend on the speciation of the contaminant [1]. The level of iron supply to sediments creates contrasting chemical pathways, each producing distinctive mineral assemblag- es. Reliable measurement of Fe redox species (Fe2+ and Fe3+) in sediments is essential for studies of pollutants or trace-element cycling. This is, however, a difficult task, because the distribution of chemical species often changes during sampling and storage. In this work the Diffusive Gradients in Thin-films technique (DGT) is investigated as a passive sampling approach used in combination with photothermal beam deflection spectroscopy (BDS) as a detection method for determination of labile Fe-redox species in sediments and natural waters. DGT offers the advantage of pre-concentration of labile (i.e. bioavailable) Fe species from the total dissolved Fe pool in sediment pore waters [2]. The advantage of using BDS [3-4] is also in avoiding contamination by using additional steps as extraction or pre-concentration. Furthermore, combined DGT-BDS provides 2D information about distribution of Fe2+ and the total Fe content in the resin hydrogels [5]. The goal of this research is to show the repeatability of this technique for determining trace amounts of Fe redox species in environmental samples.
Najdeno v: ključnih besedah
Povzetek najdenega: ...storage. In this work the Diffusive Gradients in Thin-films technique (DGT) is investigated as a passive...
Ključne besede: beam deflection spectrometry, diffusive gradients in thin-films, iron species
Objavljeno: 16.07.2019; Ogledov: 698; Prenosov: 0
.pdf Polno besedilo (29,60 MB)

14.
Effect of bead size in Chelex-based resin hydrogels in DGT on detection of Fe redox species by beam deflection spectroscopy
Dorota Korte, Arne Bratkič, Hanna Budasheva, Mladen Franko, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...Diffusive Gradients in Thin Films, Beam Deflection Spectrometry, iron species, resin...
Ključne besede: Diffusive Gradients in Thin Films, Beam Deflection Spectrometry, iron species, resin hydrogels
Objavljeno: 25.09.2019; Ogledov: 622; Prenosov: 0
.pdf Polno besedilo (1,28 MB)

15.
Developing DGT technique for determination of iron redox species by photothermal beam deflection spectrometry
Yue Gao, Dorota Korte, Chang Zhou, Arne Bratkič, Hanna Budasheva, Mladen Franko, Bruno Delille, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...Diffusive Gradients in Thin Films, Beam Deflection Spectrometry, iron redox species...
Ključne besede: Diffusive Gradients in Thin Films, Beam Deflection Spectrometry, iron redox species
Objavljeno: 25.09.2019; Ogledov: 666; Prenosov: 0
.pdf Polno besedilo (1,28 MB)

16.
Determination of Fe(III) and Fe(II) in natural waters using passive DGT samplers and non-destructive BDS analysis
Arne Bratkič, Dorota Korte, Hanna Budasheva, Mladen Franko, 2019, objavljeni povzetek znanstvenega prispevka na konferenci

Najdeno v: ključnih besedah
Povzetek najdenega: ...Deflection Spectrometry, iron species, Diffusive Gradients in Thin-films, frequency scanning...
Ključne besede: Beam Deflection Spectrometry, iron species, Diffusive Gradients in Thin-films, frequency scanning
Objavljeno: 30.09.2019; Ogledov: 727; Prenosov: 0
.pdf Polno besedilo (19,45 MB)

17.
Photoactive nanocomposite thin films on glass and thermosensitive substrates
Nives Vodišek, 2019, doktorska disertacija

Opis: Photocatalysis is a well-known process for the last few decades; it is predominantly used for water and air purification, but also for self-cleaning and antibacterial surfaces. The photocatalytic process is one of the advanced oxidation processes, where semiconductors are mainly used as photocatalysts. The most known and used semiconductor is nanosized titania, which can non-selectively decompose organic matters. One of the side effects of nano TiO2 under UV irradiation is photoinduced hydrophilicity, which furthermore improves the self-cleaning effect. The main drawback of TiO2 is that for its activation UV light is needed, which represents only 5 percent of the solar spectrum. Consequently, actinic irradiance power is low and the response of photocatalyst is limited. Novel approaches are being introduced to improve TiO2 response to visible light such as doping, coupling, modification of surface morphology and others. The thesis consists of five principal chapters. The first chapter is focused on a short literature review and explanation of some basic terms and principles that are related to this thesis. The aim of the research was to prepare transparent photocatalytically active thin films on glass and thermosensitive substrates. Four thermosensitive substrates were used: polyvinyl chloride (PVC) foil, polymethyl methacrylate (PMMA) sheet and polyester (PES) fabric coated with a polyvinyl and acrylic coating, with (D1) or without (D2) an additional polyvinylidene fluoride topcoat. The synthesis of films was modified with the introduction of zirconium aiming at improving the photocatalytic activity of the TiO2 films, and the final films had a SiO2 phase present for increased mechanical robustness. The third chapter is dedicated to the experimental part of the thesis. The detailed process of synthesis is described. The sol-gel process was used to prepare initial Ti-Zr sols, colloidal aqueous solutions with TiO2 and ZrO2 nanoparticles derived from titanium and zirconium alkoxides. The four different Ti-Zr sols were prepared with 0, 5, 10 and 20 molar % of Zr according to Ti. The depositing solution was prepared by mixing Ti-Zr sol, SiO2 sol binder, 1-propanol and 2-propoxyethanol, and then thin films were deposited by dip-coating technique. After the deposition, samples did not require high-temperature calcination since the photocatalytic anatase phase was present already after drying the deposited layers. Coated glass slides were put into a furnace at 150 °C, while samples on thermosensitive substrates were just treated by a heat gun. Samples in powder and thin film form were characterized by UV-Vis, FTIR-ATR and laser beam deflection spectroscopy, X-ray diffraction, scanning electron microscopy and thermal analysis. One of the main aspects of the photocatalyst is its activity. Photocatalytic activity of the thin films was determined, either quantitatively by the formation of fluorescent hydroxyterephthalic acid, one of the first degradation products of terephthalic acid deposit, or qualitatively by a visual-based method where degradation of resazurin ink was observed. Two additional methods were used on glass samples, electron paramagnetic resonance, and degradation of methyl stearate by observing the change in water contact angle under UVA irradiation. Mechanical stability of films on various substrates is an essential factor, describing how successful was immobilization of the photocatalytic materials on the substrate. It was determined by the pencil hardness test, i.e., Wolff-Wilborn method. In the fourth chapter, titled “Results and Discussion,” the most important part of the thesis is placed. Materials characterization and associated discussion of the results are divided into three major parts: i) powder samples characterization; ii) characterization of thin films on a glass substrate, and iii) characterization of films on thermosensitive substrates. In the conclusions, the main findings of the Ph.D. research work are summarized. One of our initial hypotheses was disapproved, thin films were not more active with a higher content of zirconium. However, they were more durable. All the obtained films were transparent and photoactive, despite the low-temperature synthesis procedure. Besides commonly used glass substrate, immobilization on thermosensitive substrates was also successful.
Najdeno v: ključnih besedah
Ključne besede: glass substrate, immobilization, nanocomposite, nanomaterials, PES, photocatalysis, PMMA, PVC, self-cleaning surfaces, silica, plastic substrates, thin films, titania, zirconia
Objavljeno: 14.10.2019; Ogledov: 818; Prenosov: 65
.pdf Polno besedilo (6,23 MB)

18.
Chemical Instability of an Interface between Silver and Bi2Se3 Topological Insulator at Room Temperature
Katja Ferfolja, Matjaž Valant, I. Mikulska, Sandra Gardonio, Mattia Fanetti, 2018, izvirni znanstveni članek

Opis: Understanding an interaction at an interface between a topological insulator and a metal is of critical importance when designing electronic and spintronic devices or when such systems are used in catalysis. In this paper, we report on a chemical instability of the interface between Bi2Se3 and Ag studied by X-ray powder diffraction and electron microscopy. We present strong experimental evidence of a redox solid-state reaction occurring at the interface with kinetics that is significant already at room temperature. The reaction yields Ag2Se, AgBiSe2, and Bi. The unexpected room-temperature chemical instability of the interface should be considered for all future theoretical and applicative studies involving the interface between Bi2Se3 and Ag.
Najdeno v: ključnih besedah
Povzetek najdenega: ...topological insulators, Ag, thin metal films, interfaces, redox reaction...
Ključne besede: topological insulators, Ag, thin metal films, interfaces, redox reaction
Objavljeno: 17.06.2020; Ogledov: 311; Prenosov: 0
.pdf Polno besedilo (3,93 MB)

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