TiO 2

One-step TiO2 nanoparticle synthesis based on the interaction between thiourea and metatitanic acid is applied for sulfur and carbon anatase codoping. The synthesis of the doped TiO2 has been monitored by means of differential thermal analysis and thermogravimetric analysis (DTA-TG), which allows determining the optimal thermal conditions for the process. Electron microscopy showed micrometer-sized (5–15 μm) randomly distributed crystal aggregates, consisting of many 15–40-nm TiO2 nanoparticles. The obtained phase composition and chemical states of the doping elements are analyzed by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared (IR) and Raman spectroscopies, and electron paramagnetic resonance (EPR). XRD displays in both samples (doped and pristine) the existence of only one crystalline phase—the tetragonal modification of TiO2—anatase. Further data assessment by means of Rietveld refinement allowed detection of a slight c lattice parameter and volume increase related to incorporation of the doping elements. XPS demonstrated the presence of carbon and sulfur as doping elements in the material. It was confirmed that carbon is in elemental form and also present in oxygen-containing compounds, which are adsorbed on the particle surface. The binding energy for sulfur electron core shell corresponds to the established data for sulfate compounds, where sulfur is in 6+ oxidation state. The synthesized S- and C-codoped TiO2 showed excellent photocatalytic performance during the degradation of organic dyes (rhodamine B, methylene blue), gas-phase oxidation of ethanol under visible light, and photocatalytic hydrogen generation from ethanol under ultraviolet light

Coronavirus and pH

This article investigates the viability of SARS-CoV-2 and its dependence on pH levels, specifically focusing on the difference between the pH stability intervals for the coronavirus and human blood. Human blood typically maintains a pH range of around 7.35 to 7.45, while SARS-CoV-2 exhibits stability within the pH range of 6.0 to 6.5. The study aims to elucidate the critical role of hemoglobin in maintaining pH balance and explores its implications for viral susceptibility. The findings emphasize the importance of reinforcing the alkalinity of the medium as a means to weaken the virus. The research contributes to the understanding of pH-dependent mechanisms in viral infections and provides valuable insights for the development of potential therapeutic strategies

Photocatalytic Degradation of 4,4′-Isopropylidenebis(2,6-dibromophenol) on Magnetite Catalysts vs. Ozonolysis Method: Process Efficiency and Toxicity Assessment of Disinfection By-Products

Flame retardants have attracted growing environmental concern. Recently, an increasing number of studies have been conducted worldwide to investigate flame-retardant sources, environmental distribution, living organisms’ exposure, and toxicity. The presented studies include the degradation of 4,4′-isopropylidenebis(2,6-dibromophenol) (TBBPA) by ozonolysis and photocatalysis. In the photocatalytic process, nano- and micro-magnetite (n-Fe3O4 and μ-Fe3O4) are used as a catalyst. Monitoring of TBBPA decay in the photocatalysis and ozonolysis showed photocatalysis to be more effective. Significant removal of TBBPA was achieved within 10 min in photocatalysis (ca. 90%), while for ozonation, a comparable effect was observed within 70 min. To determine the best method of TBBPA degradation concentration on COD and TOC, the removals were examined. The highest oxidation state was obtained for photocatalysis on μ-Fe3O4, whereas for n-Fe3O4 and ozonolysis, the COD/TOC ratio was lower. Acute toxicity results show noticeable differences in the toxicity of TBBPA and its degradation products to Artemia franciscana and Thamnocephalus platyurus. The EC50 values indicate that TBBPA degradation products were toxic to harmful, whereas the TBPPA and post-reaction mixtures were toxic to the invertebrate species tested. The best efficiency in the removal and degradation of TBBPA was in the photocatalysis process on μ-Fe3O4 (reaction system 1). The examined crustaceans can be used as a sensitive test for acute toxicity evaluation

Photocatalytic Degradation of 4,4′-Isopropylidenebis(2,6-dibromophenol) on Sulfur-Doped Nano TiO2

In present work, we examine the photocatalytic properties of S-doped TiO2 (S1, S2) compared to bare TiO2 (S0) in present work. The photocatalytic tests were performed in alkaline aqueous solutions (pH = 10) of three differently substituted phenols (phenol (I), 4,4′-isopropylidenebisphenol (II), and 4,4′-isopropylidenebis(2,6-dibromophenol) (III)). The activity of the catalysts was evaluated by monitoring I, II, III degradation in the reaction mixture. The physicochemical properties (particle size, ζ-potential, Ebg, Eu, E0cb, E0vb, σo, KL) of the catalysts were established, and we demonstrated their influence on degradation reaction kinetics. Substrate degradation rates are consistent with first-order kinetics. The apparent conversion constants of the tested compounds (kapp) in all cases reveal the sulfur-loaded catalyst S2 to show the best photocatalytic activity (for compound I and II S1 and S2 are similarly effective). The different efficiency of photocatalytic degradation I, II and III can be explained by the interactions between the catalyst and the substrate solution. The presence of bromine substituents in the benzene ring additionally allows reduction reactions. The yield of bromide ion release in the degradation reaction III corresponds to the Langmuir constant. The mixed oxidation-reduction degradation mechanism results in higher degradation efficiency. In general, the presence of sulfur atoms in the catalyst network improves the degradation efficiency, but too much sulfur is not desired for the reduction pathway

Вплив допованого сіркою та вуглецем TiO2 нанокомпозиту на фотокаталітичні та механічні властивості цементних розчинів

This study has established the impact of a nano-ТіО2 P25 modifier and a nanocomposite based on titanium dioxide, doped with sulfur and carbon dioxide (ТіО2/S,C), on the photocatalytic, mechanical properties and the structural formation of cement mortars. The paper reports the results of the particle size distribution of the Portland composite cement and the ТіО2 nano additives; a comprehensive assessment of the particle size distribution has been performed both in terms of volume and specific surface. It has been proven that the ТіО2/S,C nanocomposite is characterized by the extremely high surface activity, which determines the photocatalytic properties of the surface of cement mortars. The comparison of the mechanical properties of cement mortars modified by titanium dioxide nano additives has been carried out.An experimental study has confirmed the improved photocatalytic properties of the cement mortar surface in the visible spectrum through the doping of the nano-sized titanium dioxide with carbon and sulfur. A combination of the ТіО2 nano additives and the superplasticizers of polycarboxylate type leads to the increased strength of the modified samples in proportion to a hardening age. Given the high surface activity of the ТіО2/S,C nanocomposite's particles, the cement paste hydration products deposit at their surface, thereby forming such conglomerates with them that seal the microstructure of the cement matrix. It has been shown that using a nanocomposite based on the modified titanium dioxide decreases the indicators of free energy while the surface of the cement mortar acquires hydrophobic properties, which contributes to the processes of self-cleaning. Thus, there is a reason to argue about the feasibility of using the ТіО2/S,C nanocomposite to improve the photocatalytic, self-cleaning, mechanical, and hydrophobic properties of cement mortarsПроведенными исследованиями установлено влияние модификатора нано-TiO2 Р25 и нанокомпозита на основе диоксида титана, допированного серой и углеродом (TiO2/S,C), на фотокаталитические, механические свойства и структурообразования цементных растворов. Получены результаты гранулометрического состава композиционного портландцемента и нанодобавок TiO2; проведена комплексная оценка распределения по размерам их частиц как по объему, так и по удельной поверхности. Доказано, что нанокомпозит TiO2/S,C характеризуется экстремально высокой поверхностной активностью, что определяет фотокаталитические свойства поверхности цементных растворов. Проведено сравнение механических свойств цементных растворов, модифицированных нанодобавками диоксида титана.Экспериментальными исследованиями подтверждено улучшение фотокаталитических свойств поверхности цементного раствора в видимом спектре за счет допирования наноразмерного диоксида титана углеродом и серой. Сочетание нанодобавок TiO2 с суперпластификаторами поликарбоксилатного типа приводит к росту прочности модифицированных образцов с возрастом твердения. Благодаря высокой поверхностной активности частиц нанокомпозита TiO2/S,C продукты гидратации цементной пасты осаждаются на их поверхности, образуя с ними конгломераты, которые уплотняют микроструктуру цементирующей матрицы. Показано, что при использовании нанокомпозита на основе модифицированного диоксида титана показатели свободной энергии снижаются и поверхность цементного раствора приобретает гидрофобные свойства, что способствует процессам самоочищения. Таким образом, есть основания утверждать о целесообразности использования нанокомпозита TiO2/S,C для улучшения фотокаталитических, самоочищающихся, механических и гидрофобных свойств цементных растворовПроведеними дослідженнями встановлено вплив модифікатора нано-ТіО2 Р25 та нанокомпозиту на основі діоксиду титану, допованого сіркою та вуглецем (TiO2/S,C), на фотокаталітичні, механічні властивості та структуроутворення цементних розчинів. Отримано результати гранулометричного складу композиційного портландцементу та нанодобавок ТіО2; проведена комплексна оцінка розподілу за розмірами їх частинок як за об’ємом, так і за питомою поверхнею. Доведено, що нанокомпозит TiO2/S,C характеризується екстремально високою поверхневою активністю, що визначає фотокаталітичні властивості поверхні цементних розчинів. Проведено порівняння механічних властивостей цементних розчинів, модифікованих нанодобавками діоксиду титану.Експериментальними дослідженнями підтверджено покращення фотокаталітичних властивостей поверхні цементного розчину у видимому спектрі за рахунок допування нанорозмірного діоксиду титану вуглецем та сіркою. Поєднання нанодобавок ТіО2 з суперпластифікаторами полікарбоксилатного типу призводить до зростання міцності модифікованих зразків з віком тверднення. Завдяки високій поверхневій активності частинок нанокомпозиту TiO2/S,C продукти гідратації цементної пасти осаджуються на їх поверхні, утворюючи з ними конгломерати, що ущільнюють мікроструктуру цементуючої матриці. Показано, що при використанні нанокомпозиту на основі модифікованого діоксиду титану показники вільної енергії знижуються і поверхня цементного розчину набуває гідрофобних властивостей, що сприяє процесам самоочищення. Таким чином, є підстави стверджувати про доцільність використання нанокомпозиту TiO2/S,C для покращення фотокаталітичних, самоочисних, механічних та гідрофобних властивостей цементних розчині

Synthesis of Micro-Spikes and Herringbones Structures by Femtosecond Laser Pulses on a Titanium Plate—A New Material for Water Organic Pollutants Degradation

(1) Background: The shrinkage of water resources, as well as the deterioration of its quality as a result of industrial human activities, requires a comprehensive approach relative to its protection. Advanced oxidation processes show high potential for the degradation of organic pollutants in water and wastewater. TiO2 is the most popular photocatalyst because of its oxidizing ability, chemical stability and low cost. The major drawback of using it in powdered form is the difficulty of separation from the reaction mixture. The solution to this problem may be immobilization on a support (glass beads, molecular sieves, etc.). In order to avoid these difficulties, the authors propose to prepare a catalyst as a titanium plate covered with an oxide layer obtained with laser treatment. (2) Methods: In the present work, we generated titanium oxide structures using a cheap and fast method based on femtosecond laser pulses. The structurized plates were tested in the reaction of methylene blue (MB) degradation under UVA irradiation (365 nm). The photocatalytic activity and kinetic properties for the degradation of MB are provided. (3) Results: Studies of X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirm a titanium oxide layer with laser-induced generated structures that are called “spikes” and “herringbones”. The structurized plates were effective photocatalysts, and their activity depends on the structure of the oxide layer (spike and herringbone). (4) Conclusions: The immobilization of the catalyst on a solid support can be performed in a fast and reproducible manner by using the technique of laser ablation. The layers obtained with this method have been shown to have catalytic properties

The Effect of Sulfur- and Carbon-codoped TiO2 Nanocomposite on the Photocatalytic and Mechanical Properties of Cement Mortars

This study has established the impact of a nano-ТіО2 P25 modifier and a nanocomposite based on titanium dioxide, doped with sulfur and carbon dioxide (ТіО2/S,C), on the photocatalytic, mechanical properties and the structural formation of cement mortars. The paper reports the results of the particle size distribution of the Portland composite cement and the ТіО2 nano additives; a comprehensive assessment of the particle size distribution has been performed both in terms of volume and specific surface. It has been proven that the ТіО2/S,C nanocomposite is characterized by the extremely high surface activity, which determines the photocatalytic properties of the surface of cement mortars. The comparison of the mechanical properties of cement mortars modified by titanium dioxide nano additives has been carried out.An experimental study has confirmed the improved photocatalytic properties of the cement mortar surface in the visible spectrum through the doping of the nano-sized titanium dioxide with carbon and sulfur. A combination of the ТіО2 nano additives and the superplasticizers of polycarboxylate type leads to the increased strength of the modified samples in proportion to a hardening age. Given the high surface activity of the ТіО2/S,C nanocomposite's particles, the cement paste hydration products deposit at their surface, thereby forming such conglomerates with them that seal the microstructure of the cement matrix. It has been shown that using a nanocomposite based on the modified titanium dioxide decreases the indicators of free energy while the surface of the cement mortar acquires hydrophobic properties, which contributes to the processes of self-cleaning. Thus, there is a reason to argue about the feasibility of using the ТіО2/S,C nanocomposite to improve the photocatalytic, self-cleaning, mechanical, and hydrophobic properties of cement mortar

Functionalization of Polycaprolactone Electrospun Osteoplastic Scaffolds with Fluorapatite and Hydroxyapatite Nanoparticles: Biocompatibility Comparison of Human Versus Mouse Mesenchymal Stem Cells

A capability for effective tissue reparation is a living requirement for all multicellular organisms. Bone exits as a precisely orchestrated balance of bioactivities of bone forming osteoblasts and bone resorbing osteoclasts. The main feature of osteoblasts is their capability to produce massive extracellular matrix enriched with calcium phosphate minerals. Hydroxyapatite and its composites represent the most common form of bone mineral providing mechanical strength and significant osteoinductive properties. Herein, hydroxyapatite and fluorapatite functionalized composite scaffolds based on electrospun polycaprolactone have been successfully fabricated. Physicochemical properties, biocompatibility and osteoinductivity of generated matrices have been validated. Both the hydroxyapatite and fluorapatite containing polycaprolactone composite scaffolds demonstrated good biocompatibility towards mesenchymal stem cells. Moreover, the presence of both hydroxyapatite and fluorapatite nanoparticles increased scaffolds’ wettability. Furthermore, incorporation of fluorapatite nanoparticles enhanced the ability of the composite scaffolds to interact and support the mesenchymal stem cells attachment to their surfaces as compared to hydroxyapatite enriched composite scaffolds. The study of osteoinductive properties showed the capacity of fluorapatite and hydroxyapatite containing composite scaffolds to potentiate the stimulation of early stages of mesenchymal stem cells’ osteoblast differentiation. Therefore, polycaprolactone based composite scaffolds functionalized with fluorapatite nanoparticles generates a promising platform for future bone tissue engineering applications