Nanostructured titanium-dioxide thin films for environmental applications

Titanium-dioxide nanostructures and thin films are interesting for application in environmental protection, for water and air purification from toxic compounds, and photocatalytic degradation of water, where separation of H2 is important for the development of new energy sources. Furthermore, they are interesting for fabrication of solar cells, various sensor applications, transparent conducting oxides (TCO), etc [1-3]. Stoichiometric TiO2 phase has a wide optoelectronic band gap of ~3.2 eV, which makes it a dielectric at lower temperatures and a semiconductor at higher temperatures. It has a high absorption coefficient in the range of UV radiation, but low in the visible light region, and this makes significant constrains for its usage as a photocatalyst. For reducing energy gap, better absorption in visible light region and more efficient application it is necessary to add doping material species, which can be metal or non-metal ions.When used as a photocatalyst in form of a powder, TiO2 nanoparticles are embedded in photosensitizing dyes which absorb visible light, or they are partly covered with nanoparticles of some transition metal to enhance injection of charge carriers. Recent developments involve the use of physical vapor deposition (vacuum evaporation or ion sputtering) to synthesize TiO2 thin film structures, and ion implantation for their doping. The advantage of using physical vapor deposition is that the Ti:O ratio can be varied, and the films can be deposited on any supporting or large area substrates. On the other hand, ion implantation is a proven technique for introducing dopant atomic species into the crystal lattice of semiconductor materials. In these experiments TiO2 thin films were synthesized by physical vapor deposition (PVD) method, using three different procedures: (i) reactive d.c. ion sputtering of pure Ti target, using Ar ions and introducing O2 in the deposition chamber; (ii) r.f. sputtering of TiO2 target, using Ar + O2 gas mixture; and (iii) reactive e-beam evaporation of pure Ti in the presence of introduced O2 . In case of reactive d.c. ion sputtering additional experiments involved a controlled introduction of nitrogen in the interaction chamber, which yielded doping of the deposited TiO2 thin films, in reducing their band gap and enhancing absorption of visible light. The films were deposited to a thickness of a few hundred nm on silicon wafers and glass slide substrates. Structural and compositional characterization of samples included X-ray diffraction analysis (XRD), transmission electron microscopy (TEM, HRTEM), Rutherford backscattering spectrometry (RBS), and X-ray photoelectron spectroscopy (XPS). Optical characterizations were done by measuringthe transmission and diffuse reflection UV/VIS spectra. Photocatalytic activity was measured by determining the photodegradation rate of organic solutions Structural characterization revealed that as-deposited samples grow in form of a mixture of very fine nanocrystalline grains of rutile and anatase TiO2 phases and TiO. Hence, in order to homogenize the TiO2 stoichiometry andinduce the growth of larger grains it was necessary to anneal the samples in air, at temperatures of 400 and 600 o C [4]. This procedure was performed on all samples after deposition. Bright-field cross-sectional images taken from two different TiO2 films deposited on Si wafers are shown in Fig. 1. Sharp contrast regions within the films indicate their polycrystalline structure. The results of investigations showed that it is possible to tailor the structure and properties of the obtained TiO2 thin films by adjusting the processing parameters.8th Symposium Chemistry and Environmental Protection : May 30 - June 1, Kruševac, 2018

Prolonged exposure to mesoporous silica decrease cell viability in vitro

„Contemporary Materials 2021“ : XIV International Scientific Conference : programme and book of abstracts : September 9-10, 2021; Banja Luka, Bosnia and Herzegovin

The influence of hydrochloric acid on the features of SBA-15 particles

The template method synthesis of both SBA-15 materials with elongated and spherical particles was performed using a surfactant Pluronic P123. The HCl (p.a.) was used to synthesize material with elongated particles connected in chain structures grouped into shapes resembling sheaves of wheat. In the synthesis of spherical SBA-15 with diameters ranging from 0.5 to 2 μm, a spent HCl solution which was obtained after chemical treatment of clay was used where the dominant presence of the spheres was confirmed by the SEM method. In addition to the methods mentioned above, XRD, EDS and FTIR methods characterize SBA-15 materials

Synthesis of spherical SBA-15 silica particles without the use of additional cosurfactant

The synthesis of SBA-15 material with spherical particles is performed by the template method by using only a surfactant Pluronic P123 under acidic conditions. In the synthesis of SBA-15 with spherical particles, an HCl solution was used after specialised chemical treatment of clay purification. The dominant presence of the spheres with diameters up to around 2 μm was confirmed by the scanning electron microscopy(SEM) method. In contrast, the Energy-dispersive X-ray spectroscopy(EDS) confirmed that the spheres consisted only of SiO2 in composition. In addition to the methods mentioned above, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy(FTIR) methods were used to characterise SBA- 15 materials. Application of HCl solution after chemical treatment of clay purification represents the application of technology in the synthesis of spherical SBA-15.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Mesoporous silica decrease cell viability in vitro in dose dependent manner

Mesoporous silica renders chemical and mechanical stability under biological conditions, but due to its physicochemical properties, could be potentially harmful to exposed cells. The aim of the current study was to estimate SBA-15 (concentration of 50, 100 and 250 µg/mL) impact on human peripheral blood mononuclear cells to induce cyto- and genotoxicity in vitro after 72 h treatment, as well as lipid peroxidation in serum samples ex vivo. SBA-15 mesoporous silica treatment impact on cell viability was performed by XTT assay, lipid peroxidation was estimated by determining malondialdehyde and 4-hydroxyalkenals levels and genotoxicity by micronucleus assay. SBA-15 treatments displayed genotoxic potential at the lowest concentration, while highest tested concentration led to decrease of cell viability and increase of lipid peroxidation. Chemical modification of SBA-15 material that could influence its physicochemical properties could be useful way to lower its toxicity

Modifying Mesoporous SBA-15 by a Microencapsulation Method in the Matrix of Sodium Alginate

The present work represents hydrogel as a composite based on sodium alginate and mesoporous SBA-15. The hydrogel was obtained by modifying mesoporous SBA-15 by a microencapsulation method of the SBA-15 in the sodium alginate matrix. The solution of CaCl2 provided a gelation complex of sodium alginate/SBA-15 in a rigid gel-like structure. The sodium alginate/SBA-15 hydrogels beads of about 3 mm diameter were prepared. Composite material was characterized by using powder X- ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. This composite material may have potential application in removal of metal ions – pollutants from aqueous solutions.XVI International Conference on Fundamental and Applied Aspects of Physical Chemistry : Proceedings, Vol. 2, September 26-30, Belgrad

Wood-Waste-Derived Activated Porous Carbon Material for Pesticide Removal From Water

XVI International Conference on Fundamental and Applied Aspects of Physical Chemistry : book of abstracts, September 26-30, Belgrad

Synthesis of spherical SBA-15 silica particles without the use of additional cosurfactant

The synthesis of SBA-15 material with spherical particles is performed by the template method by using only a surfactant Pluronic P123 under acidic conditions. In the synthesis of SBA-15 with spherical particles, an HCl solution was used after specialised chemical treatment of clay purification. The dominant presence of the spheres with diameters up to around 2 μm was confirmed by the scanning electron microscopy(SEM) method. In contrast, the Energy-dispersive X-ray spectroscopy(EDS) confirmed that the spheres consisted only of SiO2 in composition. In addition to the methods mentioned above, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy(FTIR) methods were used to characterise SBA-15 materials. Application of HCl solution after chemical treatment of clay purification represents the application of technology in the synthesis of spherical SBA-15

The influence of hydrochloric acid on the features of SBA-15 particles

The template method synthesis of both SBA-15 materials with elongated and spherical particles was performed using a surfactant Pluronic P123. The HCl (p.a.) was used to synthesize material with elongated particles connected in chain structures grouped into shapes resembling sheaves of wheat. In the synthesis of spherical SBA-15 with diameters ranging from 0.5 to 2 μm, a spent HCl solution which was obtained after chemical treatment of clay was used where the dominant presence of the spheres was confirmed by the SEM method. In addition to the methods mentioned above, XRD, EDS and FTIR methods characterize SBA-15 materials