Agnieszka Magdziarz

High-value chemicals obtained from selective photo-oxidation of glucose in the presence of nanostructured titanium photocatalysts.

Glucose was oxidized in the presence of powdered TiO(2) photocatalysts synthesized by an ultrasound-promoted sol-gel method. The catalysts were more selective towards glucaric acid, gluconic acid and arabitol (total selectivity approx. 70%) than the most popular photocatalyst, Degussa P-25. The photocatalytic systems worked at mild reaction conditions: 30°C, atmospheric pressure and very short reaction time (e.g. 5 min). Such relatively good selectivity towards high-valued molecules are attributed to the physico-chemical properties (e.g. high specific surface area, nanostructured anatase phase, and visible light absorption) of novel TiO(2) materials and the reaction conditions. The TiO(2) photocatalysts have potential for water purification and energy production and for use in the pharmaceutical, food, perfume and fuel industries.

Sonication‐Assisted Low‐Temperature Routes for the Synthesis of Supported Fe–TiO2 Econanomaterials: Partial Photooxidation of Glucose and Phenol Aqueous Degradation

Fe‐doped TiO2‐supported photocatalytic materials prepared by the use of a mild ultrasound‐assisted protocol have been found to possess excellent selectivities in glucose oxidation and total phenol mineralization. These materials were characterized by a number of techniques such as XRD, diffuse reflectance UV/Vis spectroscopy, N2 physisorption, X‐ray photoelectron spectroscopy, SEM with X‐ray microanalysis, HRTEM, and flame atomic absorption spectroscopy. The proposed synthesis method was found to have a significant effect on textural properties, morphology, and visible‐light responsiveness of nanophotocatalysts. The dopant agent was found to be in the form of Fe3+ ions. The effects of the textural properties, together with the Fe presence and the adsorption ability of the material (acidic properties), seem to be involved in the optimum photocatalytic activities found for Fe–TiO2 supported on zeolite. In phenol photodegradation, although Fe doping demonstrated the detrimental effect on the conversion rate, an improvement in the direct mineralization of phenol to CO2 and water, particularly for the SiO2‐supported photocatalyst, with a negligible content of toxic byproducts in water has been observed in comparison with commercially available Evonik P25.

Iron‐Containing Titania Photocatalyst Prepared by the Sonophotodeposition Method for the Oxidation of Benzyl Alcohol

The sonophotodeposition method was applied in the synthesis of an iron‐containing titania photocatalyst. This procedure enables the use of sustainable energy sources, such as sonication and light, and eliminates the use of hazardous reducing agents. For the first time an ultrasonic horn and sun‐imitating Xenon lamp were used in this method. The following techniques: diffuse reflectance UV/Vis spectroscopy, high‐resolution transmission electron microscopy with X‐ray microanalysis (HRTEM‐EDS), X‐ray photoelectron spectroscopy (XPS) and energy‐dispersive X‐ray fluorescence (EDXRF) were applied for the characterization of the prepared material. The photocatalytic oxidation of benzyl alcohol into benzaldehyde under sun‐imitating Xenon lamp irradiation was applied as a test reaction. The photocatalyst prepared by the sonophotodeposition method showed better results, in terms of alcohol conversion and yield of benzaldehyde, in comparison with the photocatalyst prepared by an ordinary wet‐impregnation method.

In Situ Coupling of Ultrasound to Electro- and Photo-Deposition Methods for Materials Synthesis

This short review provides the current state-of-the-art of in situ coupling of ultrasound to chemical deposition methods. Synergetic action of ultrasound and light radiation or electrical fields may result in new powerful methodologies, which include sonophotodeposition and sonoelectrodeposition processes. The effect of ultrasound is explained on the basis of different physical mechanisms emerging from cavitation phenomenon. Some possible mechanisms of the interactions between ultrasound and photochemical and electrochemical processes are discussed here. The application of sonophotodeposition and sonoelectrodeposition as green energy sources in the syntheses of different nanomaterials is also reviewed.

Insight into the synthesis procedure of Fe3+/TiO2-based photocatalyst applied in the selective photo-oxidation of benzyl alcohol under sun-imitating lamp

Fe3+/TiO2/zeolite Y photocatalyst synthesized by using sonophotodeposition method was compared with photocatalysts prepared by simple photodeposition and sonodeposition methods in order to clarify the role of light irradiation and ultrasounds while they are used simultaneously. To gain an insight into the mechanism of this method a detailed characterization of the photocatalysts was carried out by means of the following techniques: UV-vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, Mössbauer measurements and photocatalytic test reaction. Basing on the results from these techniques the chemical role of light and mainly mechanical role of ultrasound were observed. The selective photocatalytic oxidation of benzyl alcohol into benzaldehyde in liquid phase was a test reaction verifying the utility of the prepared materials. The best photocatalytic efficiency in this reaction was performed by photocatalyst synthesized using compilation of ultrasound energy with photoexcitation.