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Povzetek: Titania nanoparticles were synthesized by employing the hydrothermal method and using TiOSO4as a titanium source. By varying pH between 0.5 and 1.0 and adding isopropanol to the hydrothermal reaction mixture, different mixtures of anatase, rutile, and brookite were obtained. The samples were also doped with nitrogen at different N concentrations using, respectively, urea, ammonium nitrate, and tripropylamine as nitrogen sources. The samples were characterized by X-ray powder diffraction, field emission scanning electron microscopy, infrared spectroscopy, UV-Vis diffuse reflectance spectroscopy and according to their specific surface area. Additionally, their photocatalytic activity was measured in a gas-solid reactor system. The results show that low pH favours rutile formation, whereas a higher pH yields mixed phase titania polymorphs. Isopropanol addition also favours rutile formation, and boosted the photocatalytic activity of the resulted particles. Contrary to most data in the literature, rutile turned out to be the more active phase in the present investigation. Nitrogen doping, on the other hand, did not contribute to higher photocatalytic activity, but was rather detrimental to it.
Ključne besede: titanium dioxide, rutile, hydrothermal synthesis, photocatalysis, nitrogen doping
Objavljeno v DiRROS: 26.09.2025; Ogledov: 218; Prenosov: 96
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Ključne besede: anorthosite, zeolite, hydrothermal synthesis, ZSM-5
Objavljeno v DiRROS: 21.02.2025; Ogledov: 604; Prenosov: 292
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Povzetek: New anhydrous Zn-l-tratrate was synthesized under hydrothermal conditions. Crystal structure which was solved by powder X-ray diffraction data from monoclinic unit cell (I2, a=11.7557(1), b=9.0319(1), c=5.0750(1), β=91.920(1)) consists of the three-dimensional framework where each Zn atom coordinates four tartrate ligands in distorted octahedral geometry. Due to its biocompatible components, the degradation of material was studied in aqueous media under different pH values (pH=1–7) and in the simulated body fluid (pH=7.4) performed by the measurement of the released Zn2+ concentrations at thermostatic conditions (37 °C). The results showed that under acidic conditions approximately 60% of Zn2+ is released from the investigated material after 6 h of degradation process. With the increase of the solution’s pH, the rate of degradation gradually decreases. XRD and SEM analyses indicate that in aqueous media the compound slowly disintegrates and does not undergo hydrolysis process regardless of pH. Biocompatibility of the compound and its controllable rate of degradation even in acid conditions open its potential use in the fields of bio-applications. Graphical abstract The degradation kinetics of Zn-l-tar MOF material in aqueous media at different pH conditions. Full-size image (24 K)
Ključne besede: Zn-tartrate, coordination polymers, hydrothermal synthesis, biomedical application, food supplement
Objavljeno v DiRROS: 26.01.2015; Ogledov: 6163; Prenosov: 828
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