<p>Usled visoke fotokatalitičke efikasnosti u procesima prečišćavanja voda i vazduha, titan(IV)-oksid (TiO<sub>2</sub>) se u poslednje vreme sve više ispituje u oblasti zaštiti životne okoline. Međutim usled visokih zahteva koje fotokatalizatori u ovoj oblasti treba da zadovolje, kao što su aktivnost, selektivnost, netoksičnost, ekonomičnost i stabilnost, potreba za razvojem fotokatalizatora sa povoljnijim karakteristikama se sve više nameće kao prioritet za buduća istraživanja. Inovativni pristup ove doktorske disertacije je usmeren upravo ka razvoju novih kompleksnih sistema na bazi oksida titana i slojevitih hidroksida, osvrćući se na postavljenu polaznu hipotezu o mogućem sinergetskom efektu komponenata u dostizanju visoke fotokatalitičke efikasnosti, kao i u poboljšanju njihovih opštih katalitičkih performansi. ZnAl i NiAl slojeviti hidroksidi su izabrani kao nosači aktivne komponente (TiO<sub>2</sub>). Modifikacija postojećih metoda sinteze je izvršena kako bi se pospešila interakcija aktivne komponente i nosača. Komparativna istraživanja novonastalih materijala pripremljenih primenom četiri nove metode sinteze pokazala su da se izborom metodologije sinteze i prirode interakcije između aktivne faze TiO<sub>2</sub> i aktivnog nosača mogu poboljšati fotokatalitičke performanse kompozitnih materijala u odnosu na referentne vrednosti dobijene za ZnAl slojevite hidrokside. Iako je udeo TiO<sub>2</sub> veoma mali u novonastalim kompleksnim sistemima, fotokatalitička efikasnost razgradnje model polutanta je zadovoljavajuća, usled poboljšane dostupnosti aktivnih centara i usled limitiranja aglomeracije TiO<sub>2</sub>. Potvrđeno je da metoda i uslovi sinteze bitno utiču na strukturu, teksturu i površinske karakteristike formiranih kompozita, uz rezultujuće značajne razlike i u fotokatalitičkim svojstvima sintetisanih materijala. Komparativna ispitivanja fotokatalitičke efikasnosti uz primenu odabranih test reakcija (razgradnje metilenskog plavog, rodamina B i metil oranža) pokazala su da uzorci sintetisani metodom impregnacije u baznoj sredini pokazuju najbolje fotokatalitičke performanse u širem spektru zračenja, što je pripisano formiranju faza ZnO i ZnTiO<sub>4</sub> u ovim uslovima, detektovanih XRD, FTIR i XPS analizama. Takođe, mikrobiološke analize na antimikrobno dejstvo su pokazale da, iako TiO<sub>2</sub> ne pokazuje inhibitoran efekat, uzorci sintetisani impregnacijom u baznoj sredini imaju i najizraženiji inhibitorni efekat na rast gram-pozitivnih i gram-negativnih bakterija, što dodatno ukazuje na doprinos sinergetskog efekta slojevitih oksida i aktivne faze mešovitih oksida u formiranju aktivnih centara visoke fotokatalitičke aktivnosti. Uzorci dobijeni primenom metoda koprecipitacije pokazuju nižu, ali zadovoljavajuću fotokatalitičku aktivnost, dok uzorci sintetisani metodom impregnacije u neutralnoj sredini pokazuju najnižu fotokatalitičku aktivnost i mali inhibitorni efekat.<br />Istraživanja u ovoj doktorskoj disertaciji dala su doprinos novim saznanjima o karakteristikama kompozitnih materijala tipa TiO<sub>2</sub>/ZnAl slojeviti hidroksidi bitnim za obezbeđenje fotokatalitičke aktivnosti materijala ovog tipa u širem spektru zračenja (UV/VIS), kao i ukupnih performansi koje omogućuju njihovu primenu u različitim ekološkim procesima (prečišćavanje vode i vazduha od organskih, neorganskih i bioloških polutanata).</p> / <p>Recently, titanium-dioxide (TiO<sub>2</sub>) has been extensively researched in the field of environmental protection due to its high photocatalytic efficiency in processes for water and air purification. Considering the high demands that are constantly set for photocatalysts in this field of research, such as activity, selectivity, stability, cost-effective and non-toxic, the need to develop photocatalysts with better characteristics is becoming increasingly evident as a priority for future research. The novel approach of this Ph.D. thesis is oriented towards the development of new complex systems on the basis of titanium-dioxide and layered double hydroxides, taking into account the hypothesis about their possible synergetic effect achieving high photocatalytic efficiency and obtaining better overall catalytic performances. ZnAl and NiAl layered double hydroxides have been chosen as the catalyst support of the active component (TiO<sub>2</sub>). In order to initiate the interaction between the active component and support, current synthesis methods have been modified. The novel materials were synthesized using four new different synthesis methods. Comparative investigation showed that the synthesis method, as well as the nature of the interaction between the active phase and the support can improve the overall photocatalytic performances of the composite materials when compared to the referent values obtained from ZnAl layered double hydroxides. Although the TiO<sub>2</sub> amount is low in the novel complex systems, photocatalytic efficiency for the degradation of model pollutants is satisfactory due to improved accessibility to the active centres, as well as due to limitation of TiO<sub>2</sub> agglomeration. It was confirmed that the synthesis method and conditions considerably affect the structural, textural and surface characteristics of the formed composites, resulting in significant differences in photocatalytic characteristics of the synthesized materials. Comparative research of photocatalytic efficiency in the chosen test reactions (methylene blue, rhodamine B, and methyl orange degradation) showed that the samples synthesized by the wet impregnation method in alkaline solution exhibited the best photocatalytic performance in the wide range of radiation that attributed to the formation of ZnO phase and ZnTiO<sub>4</sub> detected by XRD, FTIR and XPS analysis. Also, the research on the antimicrobial activity showed that, although TiO<sub>2</sub> has no inhibitory effect, the samples synthesized by the wet impregnation method in alkaline solution have the highest inhibitory effect on the growth of gram-positive and gram-negative bacteria, confirming the contribution of the synergic effect to the formation of active centres with high photocatalytic activity. The samples obtained by the coprecipitation method had lower, but satisfactory photocatalytic activity, while samples synthesized by the wet impregnation method in water solution showed the lowest photocatalytic activity, as well as low inhibitory effect on the bacteria growth. The research in this Ph.D. thesis contributed to the knowledge on the characteristics of novel composite materials TiO<sub>2</sub>/ZnAl layered hydroxides that are of essential importance concerning their photocatalytic activity in the wide range of radiation (UV / VIS), as well as their overall performance that enable their use in a variety of ecological processes, such purification of water and air pollution from organic, inorganic and biological pollutants.</p>
| Identifer | oai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)83240 |
| Date | 26 August 2013 |
| Creators | Hadnađev-Kostić Milica |
| Contributors | Vulić Tatjana, Marinković-Nedučin Radmila, Jovanović Dušan, Nikolić Aleksandar, Šećerov-Sokolović Radmila |
| Publisher | Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, University of Novi Sad, Faculty of Technology at Novi Sad |
| Source Sets | University of Novi Sad |
| Language | Serbian |
| Detected Language | English |
| Type | PhD thesis |
| Format | application/pdf |
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