Various microorganisms are present in natural waters, and understanding their impact on the photocatalytic behavior of photocatalysts is crucial, especially in large-scale hydrogen production. In ...line with this, we conducted a systematic investigation into the influence of Escherichia coli on the photocatalytic performance of TiO2 nanoparticles for H2 evolution. The findings revealed a significant reduction in the photocatalytic activity of TiO2 nanoparticles in the presence of Escherichia coli. Specifically, the H2 evolution rate was observed to be 57% lower (8.3 mmol g−1 h−1) compared to when Escherichia coli was absent (19.1 mmol g−1 h−1). The primary reason for this phenomenon appears to be the rupture of Escherichia coli cells during the photocatalytic process. As a result, intracellular proteins are released and subsequently adsorbed onto the surface of TiO2 nanoparticles, impeding the photocatalytic hydrogen evolution reaction. These results provide valuable insights that can inform the design of future photocatalytic hydrogen production processes.
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•Effect of E. coli on the photocatalytic activity of TiO2 nanoparticles.•Preliminary study on the influencing mechanism of E. coli.•Discover the adsorption of E. coli intracellular substances plays a key role.•Discover effect of E. coli on stability of TiO2 is negligible.•Offer data for design of photocatalytic H2 production processes.
Nanocomposites with polymer matrix offer excellent opportunities to explore new functionalities beyond those of conventional materials. TiO2, as a reinforcement agent in polymeric nanocomposites, is ...a viable strategy that significantly enhanced their mechanical properties. The size of the filler plays an essential role in determining the mechanical properties of the nanocomposite. A defining feature of polymer nanocomposites is that the small size of the fillers leads to an increase in the interfacial area compared to traditional composites. The interfacial area generates a significant volume fraction of interfacial polymer, with properties different from the bulk polymer even at low loadings of the nanofiller. This review aims to provide specific guidelines on the correlations between the structures of TiO2 nanocomposites with polymeric matrix and their mechanical properties. The correlations will be established and explained based on interfaces realized between the polymer matrix and inorganic filler. The paper focuses on the influence of the composition parameters (type of polymeric matrix, TiO2 filler with surface modified/unmodified, additives) and technological parameters (processing methods, temperature, time, pressure) on the mechanical strength of TiO2 nanocomposites with the polymeric matrix.
•Green synthesis of TiO2 nanoparticles mediated by Calendula officinalis flower extract.•Calendula officinalis extract act as a reducing and stabilizing agent without any toxic regents.•TiO2 NPs/C. ...officinalis shown good catalytic activity for reduction of 4-NP.•TiO2 NPs/C. officinalis shown good recyclability.
This study investigates the an eco-friendly synthesis for the production of titanium dioxide nanoparticles (TiO2 NPs) by employing the water-soluble flower extract of Calendula officinalis as a natural reducing and stabilizing agent. The green produced TiO2 NPs/C. officinalis were characterized using different advanced analytical techniques, including FT-IR, FE-SEM, EDS-elemental mapping, XRD, ICP-OES and TEM. It represents the TiO2 NPs were found to be spherical in shape and well distributed without agglomeration. It also revealed the particle sizes were in the range of 30–50 nm. EDX represented the Ti atomic species along with C and O are seen to be well-dispersed in a homogeneous manner. The broad absorption band appeared at 3200–3450 cm−1 assigned to OH bond stretching belong to the adsorbed water over the titanium dioxide nanoparticles. Further, newly synthesized TiO2 NPs/C. officinalis are used as a nanocatalyst for the reduction of 4-nitrophenol (4-NP). A UV–Vis spectrophotometer is employed to track the effectiveness of the reduction process. Recyclability in 8 further degradation cycles is used to assess the sustainability of this catalyst, and the results show a steady and notable degradation activity. After a week of daily treatment, the allergic conjunctivitis clinical scores in Dunkin-Hartley guinea pigs were evaluated. The guinea pigs were sensitized with intraperitoneal ovalbumin and then subjected to topical conjunctival challenge. Different doses of TiO2 NPs/C. officinalis (20 and 100 µg/kg), prednisolone (30 mg/kg), chlorpheniramine (10 mg/kg), or PBS (10 mL/kg) were administered. The levels of serum Immunoglobulins were measured by ELISA. It was observed that the levels of ovalbumin-specific IgE notably decreased. Notably, the treatment with TiO2 NPs/C. officinalis at both doses led to a notably lower clinical score for allergic conjunctivitis. Furthermore, the TiO2 NPs/C. officinalis-treated guinea pigs conjunctival tissue showed mild mononuclear infiltration compared with the intense conjunctival tissue inflammatory infiltration observed in the PBS-treated group. These data suggest that TiO2 NPs/C. officinalis may have clinical efficacy in alleviating allergic conjunctivitis.
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In this paper, we report the photocatalytic and antibacterial activities of nanosized Ti1-xAgxO2 (0.00 < x < 0.08) photocatalyst synthesized by sol-gel method. The X-ray diffraction (XRD) and Raman ...spectra reveal single phase anatase structure for all substituted samples, ruling out the presence of any secondary phase. This is well supported by TEM micrographs which show that shapes of the nanoparticles are non-spherical. UV- visible spectrum illustrates that an absorption edge shifts toward the visible region. The 4.0 mol % of Ag-doped TiO2 shows 96% degradation of methylene blue (MB) within 60 min under visible light irradiation and exhibit highest photocatalytic performance. The active catalyst has superb stability and durability, maintaining its high degradation efficiency as more as 89% after the five successive runs. An enhancement in bactericidal activity is also observed against bacterial strain (Escherichia Coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Enterobacter Cloacae) with increased Ag substitution.
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•Ag- doped TiO2 nanoparticles were synthesized and characterized.•The structural properties were analyzed by XRD and TEM.•The photocatalytic results indicate that Ag-doped TiO2 nanoparticles effectively degrade MB under the visible light.•An enhancement in bactericidal activity is also observed against bacterial strain.
Drilling fluids tend to be used for the drilling of deep wells to clean and transport the rock cuttings, maintain the hole integrity, lubricate and cool the drill bit, and control the formation ...pressures. The present work aims at improving the water-based drilling fluid properties by using the TiO2/polyacrylamide (PAM) nanocomposite additive. This additive was obtained through the polymerization of acrylamide monomer in the presence of TiO2 nanoparticles using the solution polymerization method. The TiO2/PAM nanocomposite was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Ultraviolet–visible (UV–Vis) spectroscopy, scanning electron microscopy (SEM), and dynamic light scattering (DLS). The rheological and filtration properties of the nano-enhanced water-based drilling fluid (NWBF) were investigated using the rotational viscometer and low temperature and pressure filter press apparatus. The results indicated that the additive contributes to an increase in the viscosity and a decrease in the fluid loss and filter cake thickness.
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•TiO2/PAM nanocomposite synthesis as additive to modify the conventional drilling fluid.•Viscosity of drilling fluid increased with increasing nanocomposite content.•Fluid loss and filter cake thickness decreased with increasing nanocomposite content.•Stability of drilling fluid in different nanocomposite concentrations was investigated.
•Cellulose produced by Gluconoacetobacter xylinum does not have antibacterial properties.•CQD-TiO2 nanoparticles have antibacterial properties against Staphylococcus aureus bacteria.•BC/CQD-TiO2 ...nanocomposite can be used as an antibacterial wound healing bandage.•Scratch test indicated that the BC/CQD-TiO2 was effective in wound healing.
Antibacterial dressing can prevent the occurrence of many infections of wounds. Bacterial cellulose (BC) has the ability to carry and transfer the medicine to achieve a wound healing bandage. In this study, Carbon Quantum Dots-Titanium dioxide (CQD-TiO2) nanoparticles (NP) were added to BC as antibacterial agents. FTIR Spectroscopy illuminated that NPs were well-bonded to BC. Interestingly, MIC test proved that BC/CQD-TiO2 nanostructure (NS) has anti-bacterial properties against Staphylococcus aureus. The findings indicated that, CQD-TiO2 NPs have stronger antibacterial properties with better tensile strength compared to CQD NPs, in a concentration-dependent manner. Toxicity of CQD-TiO2 NPs on human L929 fibroblast cells was also evaluated. Most importantly, the results of the scratch test indicated that the NS was effective in wound healing in L929 cells. The approach in this study may provide an alternative to make an antibacterial wound dressing to achieve an effective drug-based bandage.
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•Calcination temperature affects sorption and photocatalytic property of TiO2/SiO2.•TiO2/SiO2-800 with anatase–rutile interphase showed high photocatalytic activity.•TiO2/SiO2-800 ...with Ti–O–Si linkage induced generation of Ti3+.•Phenanthrene sites of high Fukui index prefer to be attacked by •OH and •O2–•Potential energy surface profile shows energy evolution on phenanthrene degradation.
Quantitative identification on reactive sites of target organic molecule during photocatalysis can help to get deep insight into the pollutant degradation pathway and energy evolution process. In this study, a new class of silica aerogel supported TiO2 (TiO2/SiO2) photocatalysts were fabricated via a two-step approach, and applied for adsorption and photocatalytic degradation of phenanthrene. Anatase crystalline structure was formed upon calcination at 400 and 600 °C, while mixed crystal interphases of anatase and rutile were generated at 800 °C (anatase:rutile = 0.67:0.33). The higher calcination temperature resulted in better crystallinity of TiO2, higher photocatalytic activity, and reduced adsorption affinity toward phenanthrene. TiO2/SiO2-800 (TiO2/SiO2 calcined at 800 °C) showed minimal phenanthrene uptake (~5.2%) but the strongest photocatalytic activity, and it was able to completely degrade phenanthrene within 3 h. The SiO2 aerogel component in the composite enabled the pre-concentration of phenanthrene on the photoactive sites, while the nanoscale mixed-phases of anatase and rutile of TiO2/SiO2-800 act as an efficient transfer medium for photo-induced charge carriers. Moreover, the formed Ti–O–Si linkage in TiO2/SiO2-800 induced formation of Ti3+ under solar light irradiation, promoting photoexcited electron trap and separation of electron-hole pairs. Based on the degraded phenanthrene intermediates/products, theoretical calculations according to the density functional theory (DFT) reveal that the atoms of phenanthrene with high electrophilic Fukui index (f-) are the most reactive sites towards the radicals. Potential energy surface profile for phenanthrene degradation further reveals the intermediates energy evaluation via radicals attack.
In this study, the experimental investigation on the effects of temperature and concentrations of nanoparticles on the dynamic viscosity of water-based Al2O3-CuO-TiO2 ternary hybrid nanofluid has ...been presented. The experiments were performed in the solid vol. fraction range of 0.01–0.1%, and temperature range of 35°C to 50 °C. Furthermore, the SEM image, together with an EDX analysis of 0.05% vol. fraction ternary hybrid nanofluid has been investigated. Experimental results revealed that the dynamic viscosity enhances with an increase in the solid vol. fractions and decreases with increasing temperature. However, the maximum enhancement of dynamic viscosity of 55.41% and 17.25% has been observed for 0.1% vol. fraction of ternary hybrid nanofluid compared to water-based Al2O3-TiO2 and Al2O3-CuO hybrid nanofluids, respectively, at a temperature of 45 °C. Due to the increase in the interior resistance of fluid and ternary hybrid, nanofluids have a weaker result on the viscosity. Also, with an increment of the temperature from 35 °C to 45 °C, a 23.64% decrement in dynamic viscosity is observed for ternary hybrid nanofluid. Finally, an accurate correlation with a maximum deviation of 1.5% has been proposed to predict the dynamic viscosity of Al2O3-CuO-TiO2/water ternary hybrid nanofluid.
Previous studies have reported that nanoparticles (NPs) and heavy metals are toxic to the environment. However, the jointed toxicity is not yet well understood. This study was aimed to investigate ...the combined toxicity of TiO2 NPs and the heavy metal cadmium (Cd) to plants. Rice (Oryzasativa L.) was selected as the target plant. The rice seedlings were randomly separated into 12 groups and treated with CdCl2 (0, 10 and 20 mg/L) and TiO2 NPs (0, 10, 100 and 1000 mg/L). The plant height, biomass and root length indicated significant toxicity of Cd to the growth, but TiO2 NPs exhibited the potential ability to alleviate the Cd toxicity. Transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS) confirmed the existence of TiO2 NPs in plants. Elemental analysis of Ti and Cd suggested that the presences of Cd significantly decreased the Ti accumulation in the rice roots in the co-exposure treatments. Interestingly, TiO2 NPs could lower the Cd uptake and distribution in rice roots and leaves. The results of antioxidant enzyme activity, lipid peroxide as well as phytohormones varied in the different treatments. Comparing with the Cd alone treatment, the net photosynthetic rate and chlorophyll content were significantly increased in the co-exposure treatments, suggesting that TiO2 NPs could tremendously reduce the Cd toxicity.
•The addition of TiO2 NPs alleviated the toxicity of CdCl2.•TiO2 led to the adsorption of Cd and Cd increased the uptake of TiO2.•TiO2 NPs absorbed Cd might be the reason for mechanism of alleviation.•TEM and EDS provided solid evidence.
The possible application of TiO2 nanoparticles (nano-TiO2) to alleviate arsenic bioaccumulation in rice seedlings and such a functioning with their crystalline structure were investigated. ...Specifically, nano-TiO2 with anatase and rutile structures and the bulk TiO2 at 0, 10, 100, and 1000 mg/L were amended to the hydroponic exposure systems with arsenic concentration at 1 mg/L, and the plant was exposed for 7 days. Our findings indicated that nano-TiO2 significantly reduced arsenic bioaccumulation in rice seedlings by 40–90% via strong sorption process, but their growth was not affected. Nano-TiO2 amendment notably alleviated oxidative stress resulting from arsenic exposure. Without nano-TiO2 amendment, the iron plaque on root surfaces served as a strong barrier to inhibit arsenic uptake by rice seedlings. Interestingly, nano-TiO2 amendment significantly decreased the iron plaque amount by 50–63% and weakened the arsenic retention in this barrier by 47–99%, further verifying the overwhelming superiority of nano-TiO2 in inhibiting arsenic uptake by rice seedlings. Rutile nano-TiO2 (NRT) at 1000 mg/L presented to be a promising candidate for controlling arsenic uptake by the exposed rice seedlings, with no significant oxidative stress by the amended nano-TiO2, thereby mitigating health risk of arsenic to humans via food chain.
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•Nano-TiO2 reduced As accumulation in plant by 40–90% due to strong sorption process.•Nano-TiO2 alleviated oxidative stress to rice seedlings resulting from As exposure.•Nano-TiO2 decreased the amount of iron plaque at rice root surfaces by 50–63%.•NRT at 1000 mg/L is appropriate for As pollution control for rice plant.
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