Change search
ReferencesLink to record
Permanent link

Direct link
Sol-gel Synthesis and Photocatalytic Characterization of Immobilized TiO2 Films
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
2009 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

   Contamination of surface and ground water from industrial wastes and anthropogenic activities represents one of the greatest challenges to the sustainable development of human society. Heterogeneous photocatalysis, a kind of advanced oxidation process characterized by the production of highly oxidative hydroxyl radicals, is a relatively novel subject with tremendous potential in water treatment applications.

    The purpose of this research was first to develop feasible hydroxyl radical detection methods, which can be used to evaluate efficiency of photocatalytic process, and second to prepare immobilized TiO2 films with high photocatalytic activities by the sol gel method.

    The feasibility of Indigo carmine and phthalic hydrazide as OH-radical probes was investigated. The organic dye Indigo carmine absorbs visual light strongly at 610 nm and its destruction can be monitored conveniently in a spectrophotometer. Results showed that both ·OH and HO2· can bleach Indigo carmine, and the bleaching yield of ·OH was pH independent. The photocatalytic dye bleaching in black light UV illuminated Degussa P25 TiO2 aerated suspensions was then investigated. A strong pH dependency of the bleaching yield was found.  This implies that the quantum yield of OH radical at pH 3 is one fourth compared to that at pH 10. The reaction of the OH radical with phthalic hydrazide will form strongly chemiluminescent 3-hydroxyphthalic hydrazide. Using the more specific phthalic hydrazide as OH radical probe, an even stronger pH dependent quantum yield of OH radical was found. At pH 10 the quantum yield reached the same magnitude as that obtained by using Indigo carmine, whereas the quantum yields at acidic pH were close to zero. However it was found that the addition of phosphate and fluoride anions can substantially enhance the OH radical yield at acidic pH by blocking the adsorption of phthalic hydrazide onto the TiO2 surfaces. Hence the adsorption of phthalic hydrazide to TiO2 is an important factor to consider when this method is used.

    Photocatalytic TiO2 films coated on metal plates were prepared by a sol gel method using titanium isopropoxide as TiO2 precursor and isopropanol as solvent. The photocatalytic activity of the obtained films was evaluated by bleaching of indigo carmine at pH 9 under black light UV irradiation. The effect of the molar ratio of isopropanol, water and hydrochloric acid to titanium isopropoxide was studied. It was also shown that the activities of TiO2 films are considerably influenced by calcination temperature, coating cycles and the supporting materials.

Abstract [sv]

    Förorening av yt- och grundvatten från industrier och humana aktiviteter utgör en av de största utmaningarna för en hållbar utveckling av det mänskliga samhället. Heterogen fotokatalys, en slags avancerad oxidations process som kännetecknas av att starkt oxidativa hydroxylradikaler produceras, är en relativt ny teknik med stor potential för vattenrening.

    Ett syfte med detta licentiatarbete var först att utveckla och genomföra olika metoder för att detektera bildningen av hydroxylradikaler såväl i laboratoriet som i tekniska miljöer. Det andra syftet med arbetet var att syntetisera immobiliserade TiO2 filmer med hög fotokatalytisk effektivitet med en sol-gel metod.

    Möjligheten att använda indigokarmin och ftalhydrazid som OH-radikalprob undersöktes. Det organiska färgämnet indigokarmin absorberar synligt ljus starkt vid 610 nm vilket gör att dess nedbrytning lätt kan följas i en spektrofotometer. Resultaten av gammaradiolys visade att båda OH och HO2 kan bleka indigokarmin och att den blekning som härrör från OH var oberoende av pH. Fotokatalytisk blekning av indigokarmin med blacklight UV bestrålning av  Degussa P25 TiO2 suspensioner undersöktes sedan. Ett starkt pH-beroende av blekningsutbytet erhölls vilket tolkas som att kvantutbytet av OH-radikaler vid pH 3 är en fjärdedel jämfört med det vid pH 10.

    När ftalhydrazid reagerar med OH-radikaler bildas starkt kemiluminiscent 3-hydroxy-ftalhydrazid. Med denna  specifika OH-radikalprob, erhölls ett ännu starkare pH beroende. Vid pH 10 var kvantutbytet i paritet med det som erhölls med indigokarmin, medan kvantutbytet vid lågt pH var nära noll. Tillsats av fosfat-  och fluoridjoner visade sig avsevärt öka OH-radikalutbytet vid lågt pH-värde genom att blockera adsorption av ftalhydrazid på TiO2 ytorna. Adsorptionen av ftalhydrazid på TiO2 är således en viktig faktor när denna metod används.

    Fotokatalytiskt verksamma TiO2-filmer på metallplattor framställdes med sol-gel metoden med titan-isopropoxide som TiO2-prekursor och isopropanol som lösningsmedel. Den fotokatalytiska aktiviteten av TiO2-belagda plattor utvärderades genom blekning av indigokarmin vid pH 9 under blacklight UV-bestrålning. Effekten av olika proportioner mellan isopropanol, vatten och saltsyra till titan isopropoxide undersöktes. Det visade sig att denfotokatalytiska aktiviteten av TiO2-plattorna i hög grad påverkades av kalcineringstemperatur, beläggningscykler och materialet i plattorna.

Place, publisher, year, edition, pages
Stockholm: KTH , 2009. , 39 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2009:32
Keyword [en]
Photocatalysis; Hydroxyl radical; TiO2 film; Sol-gel
National Category
Chemical Sciences Chemical Process Engineering
URN: urn:nbn:se:kth:diva-10683ISBN: 978-91-7415-373-6OAI: diva2:224976
2009-06-15, Q21, Osquldasvägen 6, KTH, Stockholm, 10:00 (English)
Available from: 2009-06-24 Created: 2009-06-23 Last updated: 2010-10-19Bibliographically approved
List of papers
1. Study of Indigo carmine as radical probe in photocatalysis
Open this publication in new window or tab >>Study of Indigo carmine as radical probe in photocatalysis
2009 (English)In: Journal of Photochemistry and Photobiology A: Chemistry, ISSN 1010-6030, Vol. 202, no 2-3, 86-91 p.Article in journal (Refereed) Published
Abstract [en]

The feasibility of using Indigo carmine (IC) as a probe of free radical production in photocatalysis was elucidated by comparative studies of its bleaching by gamma radiolysis and TiO2 photocatalysis. The gamma radiation result from pH 3 to 10 shows that both (OH)-O-center dot and HO2 center dot can bleach IC and that the bleaching yields of (OH)-O-center dot is pH independent at similar to 0.7 molecules per (OH)-O-center dot. The quantum yields (phi) of (OH)-O-center dot from Degussa p25 TiO2 photocatalysis from pH 3 to 10 was determined. It was found that phi was about 4% at pH 10 and dropped to below 1% at pH 3. This agrees well with the result of photocatalysis of Fricke dosimetry at pH 1. The effects of some common inorganic anions that may affect photocatalytic systems in technical applications (Cl-, SO42-, Br-, HPO42-, B4O72-, HCO3-/CO32-) was also investigated, showing that these ions does not inhibit the photocatalytic bleaching efficiency of IC.

Indigo carmine, Photocatalysis, Gamma radiolysis, Hydroxyl radical
National Category
Chemical Sciences
urn:nbn:se:kth:diva-18268 (URN)10.1016/j.jphotochem.2008.11.008 (DOI)000264408700002 ()2-s2.0-59649105505 (ScopusID)
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2011-01-12Bibliographically approved
2. Generation of Free OHaq radicals by Black Light Illumination of Degussa P25 TiO2 Aqueous Suspensions
Open this publication in new window or tab >>Generation of Free OHaq radicals by Black Light Illumination of Degussa P25 TiO2 Aqueous Suspensions
2013 (English)In: Catalysts, ISSN 2073-4344, Vol. 3, no 2, 418-443 p.Article in journal (Refereed) Published
Abstract [en]

This work demonstrates how formation of strongly chemiluminescent 3-hydroxyphthalic hydrazide by hydroxylation of non-chemiluminescent phthalic hydrazide can be applied as a selective reaction probe to obtain information on authentic hydroxyl radical, i.e., (OHaq)-O-center dot, formation, in black light illuminated Degussa P25 TiO2 aerated suspensions in the pH range from 3 to 11. The (OHaq)-O-center dot formation was found to be strongly pH dependent. At alkaline pH, the apparent quantum efficiency of (OHaq)-O-center dot formation was estimated to be at the similar to 10(-2) level whereas at acidic pH it was near zero. Addition of phosphate and fluoride ions substantially enhanced the (OHaq)-O-center dot production in the acidic pH range. It is suggested that (OHaq)-O-center dot-radical formation in TiO2 photocatalysis can occur by oxidation of hydroxyl ions in the water layer adsorbed on TiO2 surfaces.

National Category
Chemical Sciences
urn:nbn:se:kth:diva-25347 (URN)10.3390/catal3020418 (DOI)000339586600004 ()2-s2.0-84894599333 (ScopusID)

Updated from Manuscript to Article. QC 20150309

Available from: 2010-10-19 Created: 2010-10-19 Last updated: 2015-03-09Bibliographically approved
3. Synthesis of immobilized photocatalytic TiO2 films: Effect of sol-gel preparation conditions
Open this publication in new window or tab >>Synthesis of immobilized photocatalytic TiO2 films: Effect of sol-gel preparation conditions
(English)In: Materials Chemistry and Physics, ISSN 0254-0584Article in journal (Refereed) Submitted
National Category
Chemical Sciences
urn:nbn:se:kth:diva-25348 (URN)
QS 20120327Available from: 2010-10-19 Created: 2010-10-19 Last updated: 2012-03-27Bibliographically approved

Open Access in DiVA

fulltext(1649 kB)3948 downloads
File information
File name FULLTEXT01.pdfFile size 1649 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Liao, Haidong
By organisation
Chemical SciencesChemical Process Engineering

Search outside of DiVA

GoogleGoogle Scholar
Total: 3948 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 733 hits
ReferencesLink to record
Permanent link

Direct link