SZTE  Doktori Értekezések Repozitórium (SZTE Repository of Dissertations)

Kajári Balázs

Hungarian

Belvízelöntés monitoring és előrejelző rendszer kialakítása gépi tanulási algoritmusok felhasználásával

Fazekas Ákos Ferenc

Nanorészecskékkel módosított PVDF membránok alkalmazása olajemulziók hatékony kezelésére

Balajthy Zsófia

English

Evaluation of dysplasias associated with inflammatory bowel disease

Kopasz Anna Georgina

The potential of a newly developed transgenic mouse liver platform in the investigation of hepatocellular carcinoma and perspectives on PARP inhibitor-based therapy

Shah Abedi Mahsa

`Influence of rapid heat treatment on the 
photocatalytic activity of alkaline earth 
metal titanates 
 
Doctoral (Ph.D.) Theses 
 
Mahsa Shah Abedi 
 
Supervisors: 
Dr. Zsolt Pap 
Dr. Tamás Gyulavári 
 
 
Doctoral School of Environmental Sciences 
Department of Applied and Environmental Chemistry 
Faculty of Science and Informatics, University of Szeged  
 
Szeged 
2025  
2 
 
1. Introduction 
Water pollution has become a pressing global concern, fueled by the widespread release 
of harmful contaminants into aquatic environments. Among these, the uncontrolled use of 
pesticides, pharmaceuticals, and other persistent organic pollutants poses a particularly serious 
threat to both environmental and public health. Conventional treatment methods often fall short 
in completely eliminating such compounds, especially at trace concentrations.  
In response, researchers have increasingly turned to advanced oxidation processes 
(AOPs), which are capable of degrading recalcitrant pollutants through the generation of highly 
reactive species, such as hydroxyl radicals. Among the various AOPs, photocatalysis stands 
out as a particularly promising approach. It harnesses light energy to activate specific materials 
that drive oxidative reactions, ultimately breaking down pollutants into harmless byproducts. 
However, the success of photocatalysis largely depends on the choice of photocatalyst. With 
countless options available, the challenge lies in choosing a material that meets three essential 
requirements: efficiency, cost-effectiveness, and stability. Alkaline earth metal titanates are 
promising photocatalysts with a special crystal structure known as perovskite. They are 
chemically stable, relatively inexpensive, and environmentally friendly, making them good 
candidates for photocatalytic applications. Despite their potential, these materials have not been 
studied as much as others like titanium dioxide (TiO2). Like other photocatalysts, titanates have 
some limitations. Due to their relatively wide band gaps, these materials are less responsive to 
visible light, limiting their efficiency under natural sunlight. This makes it essential to carefully 
design and optimize their synthesis to achieve desirable structural and functional properties.  
This thesis focuses on the synthesis, characterization, and photocatalytic evaluation of 
alkaline earth metal titanates for the degradation of pollutants, such as phenol, chlorophenol, 
and oxalic acid, under UV light. It also explores their ability to disinfect water by inactivating 
harmful microorganisms. By optimizing synthesis conditions and investigating structure-
activity relationships, this work aims to contribute to the development of efficient and 
sustainable photocatalysts for environmental applications. 
3 
 
2. Objectives 
The primary goal of the research carried out during the PhD period was to synthesize 
alkaline earth metal (Sr, Ca, Ba) titanates using various synthesis methods and evaluate 
their performance in the degradation of pollutants. Based on the results of these measurements, 
I aim to reveal the causal relationship between the morpho-structural properties and 
photocatalytic activity. 
This thesis explores and clarifies the topics outlined above, highlighting the novelty of 
employing the rapid heating as an innovative approach for calcination, and presents the 
following primary and additional objectives: 
1. Employ sol-gel-derived materials and apply rapid heat treatment. 
2. In-depth characterization of photocatalysts to study morpho-structural properties: 
i. Crystalline composition and primary crystallite size 
ii. Optical properties of the obtained materials  
iii. Surface species and chemical composition 
3. Assess photocatalytic efficiency under UV light using various model pollutants with 
different functional groups: 
i. Hydroxyl group (-OH), associated with phenol 
ii. Halide group (-Cl), associated with chlorophenol 
iii. Carboxyl group (-COOH), associated with oxalic acid 
4. Establish the relationship between morpho-structural properties and photocatalytic activity. 
5. Evaluate the stability of the photocatalysts by conducting structural characterization after 
the degradation experiments. 
6. Perform reusability tests to assess the recyclability of the photocatalysts by repeating the 
degradation process. 
7. Conduct immobilization tests using phenol to assess the viability of the materials above 
laboratory scale. 
8. Investigate the antimicrobial effects of hydrothermally synthesized samples.  
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3. Experimental methods 
3.1. Synthesis of titanate samples 
Strontium (STO), calcium (CTO), and barium (BTO) titanates were synthesized via 
sol-gel methods. Although hydrothermal and coprecipitation approaches were also explored in 
preliminary studies, the sol-gel route was ultimately chosen because the resulting catalysts 
proved to be overall the most effective. In this method, precursors were combined at a 1:1 
molar ratio and vigorously stirred to form a homogeneous sol, which was then dried in a 
Memmert UNB500 oven to obtain a gel. The resulting xerogels were calcined using the rapid 
heating short exposure (RHSE) method [1]. 
All sol-gel samples were prepared following the same approach: components were 
mixed to achieve a stoichiometric Sr/Ca/Ba:Ti molar ratio of 1:1, followed by drying to form 
a gel and calcination of the xerogels to obtain crystalline materials. Calcination was conducted 
via the RHSE method with a constant air flow of 0.5 L/min. The temperature was increased in 
three stages (60, 20, and 10 °C/min) with the heating rate gradually reduced near the target 
temperature to prevent overheating. Once the target was reached, the temperature was held for 
5 minutes. The calcination temperature for each catalyst was optimized based on the results of 
thermogravimetric (TG) analysis, ensuring the complete decomposition of residual organics 
and the formation of pure crystalline phases. 
X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron 
microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy 
(DRS) were used for the characterization of the materials. 
3.2. Photocatalytic activity evaluation 
Oxidation tests were conducted in a thermostated (25 °C) glass reactor illuminated by six UV-
A lamps (λmax = 365 nm). Pollutants included phenol (0.1 mM), chlorophenol (0.1 mM), and oxalic acid 
(5-10 mM). Suspensions were stirred in the dark to reach adsorption-desorption equilibrium before 
illumination. Degradation was monitored via HPLC using methanol/water or H2SO4 eluents, depending 
on the analyte. 
CO2 reduction by BTO was evaluated in a UV-illuminated quartz microreactor using 
a CO2:H2 (1:2) gas mixture. Catalysts were immobilized on a glass cylinder and pretreated with 
Ar, O2, and H2. Products were analyzed using gas chromatography with TCD and FID 
detectors. 
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Disinfection studies were carried out using hydrothermally synthesized titanates 
against E. coli and B. licheniformis, prepared following Bodor et al. [2]. Photocatalyst 
suspensions in 0.9 wt% NaCl were irradiated in a glass reactor surrounded by UV lamps. 
Colony counts were determined post-incubation. Hydroxyl radical generation was assessed via 
coumarin degradation to 7-hydroxycoumarin [3]. 
3.3. Catalyst immobilization 
The top-performing STO sample was immobilized on ceramic paper using titanium 
isopropoxide as an adhesive. After UV curing, STO suspension was spray-coated and re-dried. 
The immobilized photocatalyst was tested for phenol degradation under UV light (λ_max = 355 
nm, 40 W) with HPLC monitoring. 
4. Perspective Novel Findings 
T1: The samples prepared via the RHSE method showed comparable photocatalytic 
activity relative to conventional calcination, while being more cost-efficient. 
The RHSE method was successfully integrated into the sol-gel synthesis of alkaline earth metal 
titanates (STO, CTO, and BTO), replacing conventional calcination. This substitution resulted 
in comparable or even superior photocatalytic activity for the prepared titanate catalysts (the 
differences were within ~10% in degradation yields in all cases). From an economic standpoint, 
the RHSE method offers a more cost-efficient alternative by reducing power consumption 
across all synthesis types (STO: 1742 to 1120 kW, CTO: 1920 to 1260 kW, and BTO: 1870 to 
1320 kW) along with a shorter treatment time of 5 minutes. These advantages make rapid 
calcination a plausible method not only in terms of photocatalytic activity, but also a financially 
and environmentally attractive alternative. 
 
T2: The catalysts prepared via the RHSE method exhibited high stability against non-
acidic functional group-containing pollutants. 
The alkaline earth metal titanate catalysts demonstrated overall good structural stability during 
the photocatalytic degradation processes. When used for the degradation of phenol and 
chlorophenol (compounds containing hydroxyl and halide groups, respectively), only minor 
structural changes were observed: primarily, the formation of alkaline earth metal carbonates. 
These changes did not significantly affect photocatalytic performance. However, in the case of 
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oxalic acid (containing carboxylic groups), structural changes were observed (Ca-oxalate for 
CTO, and Sr(OH)2 for STO). Importantly, the stability of RHSE-synthesized STO was further 
investigated by comparing their activity in suspended and immobilized setups: the 
photocatalytic efficiency observed in suspension was largely maintained (the yield observed 
was only lower by ~2.5%) when the catalysts were immobilized on a ceramic paper. 
 
T3: The RHSE synthesis yielded titanium dioxide species alongside CaTiO3. The amount 
and type of titania were dependent on the calcination temperature. 
During the sol-gel synthesis of calcium titanate, 10-20 wt.% of titanium dioxide phases were 
also formed. The type of titania present on the surface of the CTO depended on the applied 
calcination temperature, with anatase and brookite phases forming at lower temperatures, and 
rutile at higher temperatures. The presence of anatase and brookite titania phases significantly 
enhanced the overall photocatalytic activity of the composite material compared to the 
commercial CTO reference, primarily attributed to improved charge separation facilitated by 
these heterojunctions. In contrast, higher calcination temperatures reduced the specific surface 
area and favored rutile formation, resulting in lower photocatalytic activity. 
 
T4: Barium titanate is more active in photocatalytic CO2 reduction than in the 
photocatalytic oxidation of different pollutants.  
BTO samples prepared using the RHSE method exhibited relatively limited activity in the 
oxidative degradation of pollutants such as phenol, chlorophenol, and oxalic acid. In contrast, 
they demonstrated remarkable performance in photocatalytic CO2 reduction. All exhibited CO 
selectivity greater than 99.95%, with conversion rates strongly correlating with specific surface 
area. A larger surface area provides more active sites for photocatalytic reactions, thereby 
enhancing interactions with reactants and promoting higher CO formation rates. This contrast 
underscores the potential of BTO materials for selective CO2 conversion to CO. 
T5: Environmental Safety of Alkaline Earth Metal Titanates 
Toxicological assessment of alkaline earth metal titanates revealed that their presence either 
does not enhance or outright decreases their inactivation efficiency against Gram-negative E. 
coli and Gram-positive B. licheniformis bacteria under UV light. Based on PL results, 
disinfection efficiency correlated with hydroxyl radical generation. It was ascertained that 
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alkaline earth metal titanates are unlikely to cause harm to microorganisms in surface or 
groundwater bodies without undergoing further changes.  
 
5. Scientific Activities 
Hungarian Scientific Bibliography (MTMT) identifier: 10081650 
 
Research Articles – related to the dissertation 
1. Mahsa Abedi, Ákos Szamosvölgyi, András Sápi, Ákos Kukovecz, Zoltán Kónya, Tamás Gyulavári, 
and Zsolt Pap 
Influence of rapid heat treatment on the photocatalytic activity and stability of strontium titanates 
against a broad range of pollutants." Catalysts 13, no. 2 (2023): 219. 
https://doi.org/10.3390/catal13020219 
SJR indicator: Q2       Impact factor2024: 4.0 
Independent citations: 4 
 
2. Mahsa Abedi, Zsejke-Réka Tóth, Milica Todea, Áron Ágoston, Ákos Kukovecz, Zoltán Kónya, 
Zsolt Pap, and Tamás Gyulavári. 
Influence of rapid heat treatment on the photocatalytic activity and stability of calcium titanates 
against a broad range of pollutants." Heliyon 10, no. 14 (2024). 
 https://doi.org/10.1016/j.heliyon.2024.e34938  
SJR indicator: Q1      Impact factor2023: 3.4 
Independent citations: 1 
 
3. Mahsa Abedi, Haythem S. Basheer, Laura Lakatos, Ákos Kukovecz, Zoltán Kónya, Tamás 
Gyulavári, and Zsolt Pap. 
Influence of Rapid Heat Treatment on the Photocatalytic Activity and Stability of Barium Titanates 
Against a Broad Range of Pollutants." Molecules 29, no. 22 (2024): 5350. 
https://doi.org/10.3390/molecules29225350 
SJR indicator: Q1      Impact factor2024: 4.6 
Independent citations: 0 
4. Tamás Gyulavári, Mahsa Abedi, Sarolta Tóth, Áron Ágoston, Gábor Veréb, Attila Bodor, Ákos 
Kukovecz, Zoltán Kónya, Katalin Perei, Zsolt Pap. 
Intrinsic and photocatalytic disinfection properties of CaTiO3, SrTiO3, and BaTiO3 alkaline earth metal 
titanate perovskites." Ceramics International, (). 
https://doi.org/10.1016/j.ceramint.2025.07.286  
8 
 
SJR indicator: Q1      Impact factor2025: 5.6 
Independent citations: 0 
 
Research Articles – unrelated to dissertation 
1. Tamás Gyulavári, Daniella Dusnoki, Viktória Márta, Mohit Yadav, Mahsa Abedi, András Sápi, 
Ákos Kukovecz, Zoltán Kónya, Zsolt Pap. 
Dependence of photocatalytic activity on the morphology of strontium titanates." Catalysts, 12(5), 523. 
https://doi.org/10.3390/catal12050523 
SJR indicator: Q2       Impact factor2024: 4 
                                                                                                         Independent citations: 8 
1. Áron Ágoston, Eszter Kanász, Lilla Balassa, Mahsa Abedi, Karolina Solymos, Csaba Bús, Ágota 
Deák, Ákos Kukovecz, Zoltán Kónya, Zsolt Pap. 
Effect of silver deposition on the material characteristics and photocatalytic activity of barium 
titanates. " Heliyon, (Submitted). 
SJR indicator: Q1      Impact factor2023: 3.4 
Independent citations: 0 
 
Summary 
Σ publications: 5      Of which related to Dissertation: 4 
Σ independent citations: 13    Of which related to Dissertation: 5 
Σ impact factor: 16     Of which related to Dissertation: 12 
 
Conference Participation – related to dissertation 
1. Abedi, M., A., Kukovecz, Á., Kónya, Z., Gyulavári, T., & Pap, Z.; Characterization and evaluation 
of photocatalytic activity of strontium titanate photocatalyst prepared by different synthesis 
methods; YOURHETCAT; Szeged (Hungary); 2022. (Oral presentation) 
 
2.  Abedi, M., Gyulavári, T., & Pap, Z.; Characterization and evaluation of photocatalytic activity of 
strontium titanate photocatalyst prepared by different synthesis methods; Chemistry conference; 
Oradea (Romania); 2022. (Poster presentation) 
 
3. Abedi, M., Szamosvölgyi, Á., Sápi, A., Kukovecz, Á., Kónya, Z., Gyulavári, T., Pap, Z.; Influence 
of rapid heat treatment on the photocatalytic activity and stability of strontium titanates against a 
broad range of pollutants; 8th International Conference on Semiconductor Photochemistry (SP 8); 
Strasburg (France). (Poster presentation)  
 
9 
 
4. Abedi, M., A., Kukovecz, Á., Kónya, Z., Gyulavári, T., & Pap, Z.; Influence of rapid heat treatment 
on the photocatalytic activity and stability of calcium titanates against a broad range of pollutants, 
8th International Conference on Semiconductor Photochemistry (SP 8); Strasburg (France). (Poster 
presentation) 
 
5. Abedi, M., Gyulavári, T., Pap, Z.; Influence of rapid heat treatment on the photocatalytic activity 
and stability of strontium titanates against a broad range of pollutants; 28th International 
Symposium on Analytical and Environmental Problems; Szeged (Hungary); 2023. (Oral 
presentation) 
 
6. Gyulavári, T., Abedi, M., Tóth, Z., Todea, M., Kukovecz, Á., Kónya, Z., Pap, Z.; Influence of rapid 
heat treatment on the photocatalytic activity and stability of calcium titanates against a broad range 
of pollutants; Belfast (Ireland); 2024. (Poster presentation) 
7. Abedi, M., Basheer, H. S., A., Kukovecz, Á., Kónya, Z., Gyulavári, T., & Pap, Z.; Influence of 
rapid heat treatment on the photocatalytic activity of barium titanates; Cluj-Napoca (Romania); 
2024. (Poster presentation) 
Conference Participation – unrelated to dissertation 
1. Abedi, M., Márta, V., Yadav, M., Kedves, Z., Gyulavári, T., Sápi, A., Kónya, Z., Kukovecz, Á., 
Pap, Z.; Strontium Titanate-Based Nanostructures for CO2 Conversion: A Step Towards a Carbon-
free Environment; Turin (Italy); 2022. (Poster presentation) 
 
6. References 
1. Pap, Z., et al., Dynamic changes on the surface during the calcination of rapid heat treated 
TiO2 photocatalysts. Applied Catalysis B: Environmental, 2012. 111: p. 595-604. 
2. Bodor, A., et al., Exploitation of extracellular organic matter from Micrococcus luteus to 
enhance ex situ bioremediation of soils polluted with used lubricants. Journal of Hazardous 
Materials, 2021. 417: p. 125996. 
3. Czili, H. and A. Horváth, Applicability of coumarin for detecting and measuring hydroxyl 
radicals generated by photoexcitation of TiO2 nanoparticles. Applied Catalysis B: 
Environmental, 2008. 81(3-4): p. 295-302. 
  
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 DECLARATION 
 
I declare that the contribution of Mahsa Shah Abedi was significant in the publication: 
“Intrinsic and photocatalytic disinfection properties of CaTiO3, SrTiO3, and BaTiO3 alkaline 
earth metal titanate perovskites” which appeared in the Ceramics International journal in July 
2025. The results reported in this article and in the Ph.D. dissertation of Mahsa Shah Abedi 
have not been used to acquire any PhD degree previously and will not be used in the future for 
the purpose of acquiring an academic degree or title. 
 
Szeged, November 24, 2025 
 
 
  
 Dr. Tamás Gyulavári 
 supervisor, first author, corresponding author 
 
 
  
 Dr. Zsolt Pap 
 supervisor, corresponding author 
 


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