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11.
12.
Bioplinski potencial Zgornje Vipavske doline
Jani Gabrijelčič, 2015, undergraduate thesis

Found in: osebi
Keywords: bioplin, anaerobna razgradnja, čistilne naprave, vhodni substrat, energija, odpadki, diplomske naloge
Published: 18.05.2015; Views: 3172; Downloads: 202
.pdf Fulltext (2,18 MB)

13.
Comparison of different characteristics of TiO[sub]2 films and their photocatalytic properties
Urh Černigoj, Primož Rebernik Ribič, Urška Lavrenčič Štangar, Polonca Trebše, 2006, original scientific article

Abstract: Comparison of different characteristics of TiOsub2 films and their photocatalytic properties
Found in: osebi
Keywords: tanki filmi, fotokataliza, UV-Vis, azo barvilo, površinska morfologija
Published: 10.07.2015; Views: 2677; Downloads: 10
URL Fulltext (0,00 KB)

14.
Development of Advanced TiO2/SiO2 Photocatalyst for Indoor Air Cleaning
Andraž Šuligoj, 2015, doctoral dissertation

Abstract: TiO2 - SiO2 composites were synthesized by low-temperature sol-gel impregnation method, using four different titania sources (P-25 from Degussa, PC500 from Millennium, CCA 100 AS and CCA 100 BS from Cinkarna, later denoted as AS and BS, respectively) and deposited on aluminium and glass carriers. Ordered and disordered mesoporous silicas were impregnated with ce{TiO2} in powder or suspension form in the Ti : Si molar ratio 1 : 1. Structure, size, band gap, chemical composition and specific surface area of nanoparticles were determined by X-ray diffraction (XRD), scanning (SEM) and transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DR-UV-vis), Fourier transform infrared spectroscopy (FT-IR) and ce{N2} physisorption. Additionally, quantity of surface hydroxyl groups, surface acidity and mechanical stability of the coatings were determined by temperature programmed Fourier transform infrared spectroscopy (TPD-IR) and Wolff-Wilborn method, respectively. The photocatalytic activity of TiO2 and TiO2 - SiO2 composites was evaluated in the photodegradation of toluene and formaldehyde, as model VOCs, under UVA light irradiation in lab-made photoreactor system with two different regimes; batch and plug-flow mode. These two VOCs are being considered as examples of two of the six major classes of indoor air contaminants. Adsorption properties of the samples with toluene, have shown that the addition of mesoporous silica was beneficial. The increase of the adsorption of the bare AS TiO2 (9.5 %) was higher in the case of ordered silica, SBA-15 (2.8 times for AS/SBA15 to 26.8 %) than disordered SiO2 KIL-2 (2.4 times for AS/KIL2 to 22.7 %) although it was significant in both types of mesoporous silica supports (over 20 %). Adsorption was found to be dependent mostly on the quantity of surface Si-OH groups. Regarding the photocatalytic activities towards toluene degradation, the results with pure TiO2 showed the fastest kinetics in case of sample AS followed by PC500 and P25. The observed behaviour was ascribed to smaller particle size, and consequently higher specific surface area. Grafting titania onto silica showed the importance of structural parameters. Most importantly, if the pore structure of bare TiO2 collapsed, this resulted in decreased activity. On the other hand, retainment of the pore structure improved the distribution of nanoparticles, crystallinity and optical properties, which resulted in improved photocatalytic activity. In the degradation of formaldehyde, it was found that adsorption and degradation abilities of the materials were much more dependent on the structural properties of the samples, i.e., the pore structure. This was explained as a consequence of the different degradation mechanisms of both pollutants. Toluene degradation is governed by the oxidation through photogenerated holes - direct oxidation, whereas in the degradation of formaldehyde, the major oxidative species are OH radicals. In addition, the same as in toluene oxidation, the activity was dependent mainly on the number of crystal defects and the band gap values, that is the oxidation and reduction potentials of the catalysts. The degradation efficiency was increased from 88 % in pure AS TiO2 to 97 % when this titania was grafted onto colloidal silica (7C). An important highlight of the thesis is synthesis of a novel photocatalyst, labelled AS7C, which comprises an acidic colloidal suspension AS as TiO2 source and colloidal silica, using a low-temperature sol-gel impregnation method. This sample used all the above mentioned properties that improve photocatalytic activity towards both pollutants. Mechanical stability of the samples was also tested. The tests showed that binder, in the form of colloidal SiO2 (in size of 25 nm) in combination with colloidal titania of appropriate size - 6 nm, produced the highest mechanical stability of the coatings, which also showed excellent photocatalytic activity. Stability of the coatings, using AS as titania source, was greatly improved. The Wolff-Wilborn test on AS coating showed no mechanical resistance, while with the optimal (in terms of photocatalytic performance) addition of 7C SiO2 binder stability was excellent (F, which is in the middle of 6B-6H hardness scale). This sample (AS7C) was also tested for release of aerosols, during operation of the reactor, which could be harmful for human health at longer exposure times. It was found that aerosols are formed, probably as a consequence of detachment of nanoparticles in the first period of photodegradation test. However, their formation in consecutive tests was greatly reduced. Last but not least, a pilot plug-flow reactor was constructed to test the photocatalyst's efficiency in one-pass degradation of toluene. Sample AS7C was able to degrade toluene at conditions applied (v= 400 mL/min, m(catalyst) = 1049 mg, C(0) = 1 ppmv), which means that the out-flow from reactor was clean of the pollutant and any possible intermediates, comprising only of humid air and CO2. Deactivation of the catalyst was found at higher air flow and higher initial concentration of the pollutant. However, the concentrations of pollutants in living conditions are few orders of magnitude lower, hence this is a promising result.
Found in: osebi
Keywords: Air remediation, TiO2 photocatalysis, Immobilization, Thin layers, TiO2/SiO2 composites
Published: 31.08.2015; Views: 4854; Downloads: 80
.pdf Fulltext (33,47 MB)

15.
Alternativni nosilci za TiO2 v procesih fotokatalize
Rok Oblak, 2015, master's thesis

Abstract: Z naraščanjem populacije na Zemlji se povečuje potreba po čisti pitni vodi, hkrati pa, zaradi dvigovanja standarda življenja, močno narašča tudi količina odpadnih vod. Za čiščenje odpadnih vod se uporabljajo številni fizikalni, biološki in kemijski procesi, katerih učinkovitost je odvisna od prisotnih onesnaževal. Napredne oksidacijske metode (NOM) se uporabljajo za razgradnjo težje razgradljivih organskih onesnaževal. Pri tem gre za kemično obdelavo odpadnih vod z namenom razgradnje organskih snovi z oksidacijo preko hidroksilnih radikalov. Dve izmed naprednih oksidacijskih metod sta tudi fotokatalitska oksidacija in fotokatalitska ozonacija. Fotokataliza običajno poteka pod UV svetlobo v prisotnosti fotokatalizatorja (npr. TiO2). Fotokatalizator je lahko suspendiran v raztopini ali pa pritrjen na različne nosilce/substrate. Drug način uporabe je sicer manj učinkovit, vendar enostavnejši in zato bolj primeren za prenos tehnologije v prakso. V svoji magistrski nalogi sem se ukvarjal z iskanjem novih nosilcev za fotokatalizator in razvojem metod za nanos TiO2 na izbrane nosilce. Kot fotokatalizator sem po opravljenih poskusih z več katalizatorji uporabil Aeroxide® TiO2 P-90, proizvajalca Evonik. Preizkusil sem dva nosilca, in sicer pletena steklena vlakna in pa mrežico iz nerjavečega jekla. Izbrana sta bila, ker sta kemijsko inertna, poleg tega pa ju je enostavno prilagajati obliki reaktorske celice. Učinkovitost nosilcev sem preverjal z razgradnjo vodnih raztopin fenola in komercialnega tekstilnega barvila, Reactive Blue 19. Razgradnjo sem izvajal v pretočnem fotoreaktorju. Za analizo vzorcev sem uporabil visokotlačno tekočinsko kromatografijo (HPLC), analizo celokupnega ogljika (TOC) in pa UV-VIS spektrofotometer. Oba nosilca sta se izkazala za učinkovita, vendar pri različnih metodah. Steklena vlakna so bila najučinkovitejša pri fotokatalitski oksidaciji, mrežica iz nerjavečega jekla pa pri fotokatalitski ozonaciji. Za oba nosilca sta bili razviti tudi metodi nanašanja TiO2.
Found in: osebi
Keywords: TiO2 fotokataliza, P90, fenol, Reactive Blue 19, pretočni reaktor, steklena vlakna, mrežica iz nerjavečega jekla
Published: 30.09.2015; Views: 3622; Downloads: 222
.pdf Fulltext (3,55 MB)

16.
17.
PREPARATION AND CHARACTERIZATION OF HIGHLY PHOTOACTIVE COATINGS ON GLASS SUPPORTS FOR DEGRADATION OF PHARMACEUTICAL SUBSTANCE PARACETAMOL IN WATER
Lidija Sinovčić, 2016, master's thesis

Abstract: Pharmaceuticals in aquatic environment are considered as emerging environmental contaminants due to their constant presence, evironmental resistance and toxic effect they could have on aquatic organisms. Studies for Slovenia have shown the presence of pharmaceutical substances in waters to be comparable with published results of pharmaceutical water pollution in Europe. As conventional methods do not reach efficient pharmaceutical removal from water sources, more powerful and effective methods like heterogeneous photocatalysis using TiO2/UV have been implemented. Titanium dioxide coatings in silicate binder were prepared by the sol-gel process and deposited on a glass support with dip-coating technique. The films showed good quality and possibility of multiple use. The characterization of the films was performed with scanning electron microscope (SEM), x-ray diffraction (XRD) and hardness test (Elcometer 501 Pencil Hardness Tester). Effectiveness and quality of prepared TiO2 coatings for photodegradation of pharmaceutical compound paracetamol (PCT) were assessed during photocatalytic treatment and compared to photolysis, a process without presence of a catalyst. Photolysis caused substantial changes in paracetamol concentration between 120 and 180 minutes of irradiation where 92% of degradation was achieved, but with no changes in mineralization. Photocatalytic treatment was much faster and effective where 95% of paracetamol degraded within 90 minutes of UV irradiation and after prolonged irradiation time from 120 to 240 minutes also mineralization of paracetamol solution increased from 59% to 83%. Accordingly, toxicity decreased, but it was still not lower than in the starting PCT solution as it was shown by acute toxicity test on Daphnia magna aquatic organisms. The master thesis represents a step forward in studying photocatalytic removal of paracetamol from water, because to my knowledge all the published investigations on this pharmaceutical up to now include photocatalyst mostly in powder and not in immobilized form, which is more advantageous from application point of view.
Found in: osebi
Keywords: Pharmaceuticals, paracetamol, titanium dioxide, photocatalytic degradation, Daphnia magna.
Published: 14.09.2016; Views: 3433; Downloads: 186
.pdf Fulltext (2,50 MB)

18.
Hydroxyl radical scavenging-based method for evaluation of TiO[sub]2 photocatalytic activity
Urška Lavrenčič Štangar, Matija Strlič, Romana Cerc Korošec, Danijela Pucko, 2013, original scientific article

Abstract: Hydroxyl radical scavenging-based method for evaluation of TiO[sub]2 photocatalytic activity
Found in: osebi
Keywords: titanium dioxide, photocatalysis, N, N-(5-nitro-1, 3-phenylene)bisglutaramide, radical scavenger, HPLC
Published: 05.01.2016; Views: 2356; Downloads: 15
URL Fulltext (0,00 KB)

19.
Towards efficient removal of contaminants from households grey waste water: Photocatalytic ozonation process
Urška Lavrenčič Štangar, Marko Kete, 2015, published scientific conference contribution abstract (invited lecture)

Found in: osebi
Keywords: compact reactor, immobilized TiO2, porous alumina monolith, LAS, PBIS, RB19
Published: 01.02.2016; Views: 2379; Downloads: 0
.pdf Fulltext (6,39 MB)

20.
Efficient mineralization of greywater pollutants by photocatalytic ozonation: catalyst and reactor design
Marko Kete, Urška Lavrenčič Štangar, 2015, published scientific conference contribution abstract

Found in: osebi
Keywords: immobilized TiO2, silica binder, alumina monoliths
Published: 01.02.2016; Views: 2312; Downloads: 1
.pdf Fulltext (4,20 MB)

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