magistrsko delo
Urška Petrač (Author), Urška Lavrenčič Štangar (Mentor), Mitja Kolar (Thesis defence commission member), Romana Cerc Korošec (Thesis defence commission member)

Abstract

Hidroksilni radikali so zelo reaktivni in neselektivni, z njimi lahko razgradimo tudi zelo stabilne organske molekule. To izkoriščajo napredne oksidacijske tehnike čiščenja, ki se uporabljajo za čiščenje odpadnih vod. Mednje spada tudi fotokataliza s TiO2. Hidroksilne radikale lahko generiramo, če TiO2 v vodi obsevamo z UV svetlobo. Učinkovitost fotokatalize je odvisna od pogojev v raztopini in lastnosti fotokatalizatorja. Slednje lahko optimiziramo s spreminjanjem pogojev pri sintezi. Pri eksperimentalnem delu sem določila vpliv parametrov hidrotermalne sinteze na lastnosti nanostrukturiranega TiO2 fotokatalizatorja. Pri sintezi sem spreminjala vsebnost dodanega H2O2 in NaOH, čas in temperaturo hidrotermalne sinteze ter čas in temperaturo termične obdelave. Z UV-Vis spektroskopijo sem določila fotokatalitsko aktivnost vzorcev, z adsorpcijskimi BET izotermami specifično površino, prisotnost kristaliničnih faz sem ugotavljala z rentgensko praškovno difrakcijo, z vrstično elektrosnko mikroskopijo pa sem opazovala morfologijo nastalih delcev. Vrstična elektronska mikroskopija je pokazala, da pri sintezi nastanejo nanostrukturirani mikrodelci v obliki rožic. Njihovo obliko določi že hidrotermalna sinteza, pogoji pri termični obdelavi pa vplivajo na njihovo kristaliničnost in fotokatalitsko aktivnost. Pri višji temperaturi termične obdelave so delci bolj kristalinični in reakcija razgradnje barvila poteka hitreje. Prav temperatura termične obdelave najbolj vpliva na fotokatalitsko aktivnost, ostali parametri imajo majhen vpliv ali pa ne vplivajo. Rezultati adsorpcijskih BET izoterm kažejo, da tudi na specifično površino delcev najbolj vpliva temperatura termične obdelave, kar potrdijo tudi posnetki z vrstičnim elektronskim mikroskopom. Ugotovila sem, da se pri večkratni uporabi fotokatalizatorju njegova aktivnost ne poslabša.

Keywords

titanov dioksid;hidrotermalna sinteza;nanostrukturirani delci;fotokataliza;polprevodniki;fotokatalizatorji;čiščenje odpadnih vod;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [U. Petrač]
UDC: 546.82-31:620.3(043.2)
COBISS: 47665411 Link will open in a new window
Views: 665
Downloads: 180
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Other data

Secondary language: English
Secondary title: Hydrothermal synthesis of nanostructured TiO2 photocatalyst
Secondary abstract: Hydroxyl radicals are very reactive and unselective, they can decompose very stable organic molecules. Advanced oxidation processes based on this decomposition are used to purify wastewater. Photocatalysis with TiO2 is one of these processes. By irradiating TiO2 in water with UV light, hydroxyl radicals can be generated. The efficiency of photocatalysis depends on the conditions in the solution and the properties of the photocatalyst. The properties can be optimized by changing the synthesis conditions. In the experimental work, the influence of the synthesis parameters on the properties of the nanostructured TiO2 photocatalyst was determined. Various synthesis parameters were changed, including the added amount of H2O2 and NaOH, the duration and temperature of hydrothermal synthesis, and the duration and temperature of thermal treatment. The photocatalytic activity of the samples was determined by UV-Vis spectroscopy, the specific surface area was determined by BET adsorption isotherm, the structure was determined by X-ray diffraction and the morphology of the formed particles was observed by scanning electron microscope. The experiments showed that nanostructured flower-like microparticles are formed during the synthesis. Their shape is already determined by hydrothermal synthesis, the conditions of thermal treatment affect their crystallinity and photocatalytic activity. At higher temperatures, the particles have a higher degree of crystallinity and the dye in the solution is degraded more rapidly. The temperature of thermal treatment has the greatest influence on the photocatalytic activity, while other parameters have little or no influence. The results of BET adsorption isotherms show that the specific surface area of the particles is also most affected by the temperature of thermal treatment, which is also confirmed by scanning electron microscope. The results show that the repeated use of a photocatalyst does not reduce its activity.
Secondary keywords: titanium dioxide;hydrothermal synthesis;photocatalyst;wastewater treatment;
Type (COBISS): Master's thesis/paper
Study programme: 1000375
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemija
Pages: 62 str.
ID: 12349063