Different Concentrations Of TiO2 Nanoparticles Research Articles

Stability and rheological properties of nanofluids stabilized by SiO2 nanoparticles and SiO2-TiO2 nanocomposites for oilfield applications

SiO2 nanofluids are advanced nanomaterials in which SiO2 nanoparticles (NPs) due to high specific surface area and dispersion stability may provide promising possibilities for various applications including their use for oilfield industries. However, SiO2 NPs (being solid charged particles) tend to aggregate and form NP clusters which are subjected to prematurely settle with time thus, rendering unstable and rheologically damaged nanofluid. In this work, a nanoparticle viz., TiO2 (∼50 nm) with concentration of 0.05 and 0.1 wt% was tested as co-stabilizer to improve the stability of SiO2 nanofluid [0.5 wt% SiO2 in base of polyacrylamide (PAM), called SN nanofluid] via reducing the homoaggregation and rate of sedimentation (ROS). SN nanofluid prepared using 0.5 wt% SiO2 in the presence of different concentrations of TiO2 NPs (0.05 and 0.1 wt%), called STN nanofluids, was also analyzed by dispersion stability, SEM, EDS, DLS, UV–vis, electrical conductivity, and rheological studies. Compared to SN nanofluid (dispersion stability ≈6 weeks), STN nanofluids exhibited enhanced dispersion stability of more than 10 weeks with reduced size of NP aggregates, consistent with SEM and EDS results. Electrical conductivity and UV–vis results support that SiO2 aggregates in presence of TiO2 remain suspended for longer time than sole SiO2 aggregates as witnessed by improved absorbance and electrical conductivity. Moreover, the effect of shear deformation on rheological properties (viscosity and viscoelastic moduli) of STN nanofluids was marginal than SN nanofluid, mainly due to the presence of TiO2 NP which in presence of SiO2 collectively formed nanocomposites of SiO2-TiO2 which controlled the properties of nanofluid. The study highlighted important aspects of colloidal suspensions and is a forward step towards the use of SiO2 based nanofluid for industrial applications.

Influence of TiO2 nano-particles on charge carrier transport and cell performance of PMMA-LiClO4 based nano-composite electrolytes

The plasticized PMMA-LiClO4 based solid polymer nano-composite electrolytes were prepared for different concentrations of TiO2 nano-particles using standard solution cast technique. The structure, glass transition temperature, thermal stability and particle size of these nano-composites have been studied by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis and transmission electron microscopic analysis respectively. The complex conductivity spectra have been measured in the frequency range of 0.01 Hz–2 MHz and analyzed using random barrier model. The contribution of the electrode polarization in low frequency region and at high temperatures has been taken into account during analysis. The temperature dependence of ionic conductivity and relaxation time has been found to obey the Vogel-Tammann-Fulcher relation. A maximum ionic conductivity of ∼3.0 × 10−4 Scm−1 has been observed for the electrolyte with 1 wt% TiO2 nano-particles. The dielectric spectra have been analyzed using Havriliak-Negami function to understand the relaxation of charge carriers. The ion-ion and ion-polymer interactions have been studied using Fourier transform infrared (FTIR) spectra. Finally, the cycling performance of a coin cell of configuration graphite/PMMA-LiClO4-30 wt% PC-1wt% TiO2/LiCoO2 evaluated at 25 °C indicates suitability of the nano-composites as solid electrolytes for Li ion polymer cell.

Antibacterial Applications of Anatase TiO<SUB>2</SUB> Nanoparticle

Many methods have been used for the preparation of nanostructured metal oxides. Here we report the synthesis of TiO2 nanoparticles by facile hydrothermal process by varying the concentration of the precursor and reaction temperature while keeping the process time constant. Morphological, structural and optical studies were carried out by scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray powder diffraction spectroscopy and VU-Vis-NIR spectroscopy. Morphological and compositional analysis reveal that the prepared nanoparticles are highly pure with an approximate average particle size 5-15nm. XRD studies showed their crystalline structure and the sizes around 5 nm, while the optical absorption studies in the photon wavelength range 300-600 nm reveal that the strong absorbance peak is positioned at around 3.5 eV nm whereas visible energy is almost transparent for the materials. Finally, the antibacterial effect of TiO2 nanoparticles has been studied. Plating technique was used to determine lowest concentration that prevent or inhibit growth of bacteria. This technique of TiO2 nanoparticle was used against most common organisms which cause wound infection including: MRSA, E. coli and Pseudomonas aeruginosa. Different concentrations of TiO2 nanoparticles were used 100 μg/ml, 200 μg/ml, 400 μg/ml, 600 μg/ml and 800 μg/ml. Inhibition of bacteria was different for prepared TiO2 samples due to different concentration of the precursors and synthesis temperature.

Revelation of Different Nanoparticle-Uptake Behavior in Two Standard Cell Lines NIH/3T3 and A549 by Flow Cytometry and Time-Lapse Imaging.

The uptake of nanomaterials into different cell types is a central pharmacological issue for the determination of nanotoxicity as well as for the development of drug delivery strategies. Most responses of the cells depend on their intracellular interactions with nanoparticles (NPs). Uptake behavior can be precisely investigated in vitro, with sensitive high throughput methods such as flow cytometry. In this study, we investigated two different standard cell lines, human lung carcinoma (A549) and mouse fibroblast (NIH/3T3) cells, regarding their uptake behavior of titanium dioxide NPs. Cells were incubated with different concentrations of TiO2 NPs and samples were taken at certain time points to compare the uptake kinetics of both cell lines. Samples were analyzed with the help of flow cytometry by studying changes in the side and forward scattering signal. To additionally enable a detection via fluorescence, NPs were labeled with the fluorescent dye fluorescein isothiocyanate (FITC) and propidium iodide (PI). We found that NIH/3T3 cells take up the studied NPs more efficiently than A549 cells. These findings were supported by time-lapse microscopic imaging of the cells incubated with TiO2 NPs. Our results confirm that the uptake behavior of individual cell types has to be considered before interpreting any results of nanomaterial studies.

Evaluation of Bioactivity and Biocompatibility of Silk Fibroin/TiO2 Nanocomposite

Biodegradable polymer/bioceramic nanocomposites are osteoconductive and can accelerate healing of bone tissue. In this research, silk fibroin (SF)/titanium dioxide (TiO2) nanocomposites were synthesized using different concentrations of TiO2 nanoparticles (0, 5, 10, 15 and 20 wt%). The SF/TiO2 nanocomposites were studied in terms of bioactivity and biocompatibility. The in vitro assessment of osteoblasts compatibility indicated that SF inclusion rendered nanocomposite biocompatible whereas presence of TiO2 nanoparticles allowed the cells to adhere and grow on nanocomposite surface and enhanced the bioactivity of the composite.

Different Concentrations of Titanium Dioxide Nanoparticles Induce Autophagy Followed by Growth Inhibition or Cell Death in A375 Melanoma Cells

: Dysregulation of autophagy is currently known as a contributing factor to tumorigenesis. Accordingly, exploring novel compounds with autophagy - modulating properties is a priority in cancer research. While a number of synthetic compounds have been developed, autophagy - modulating Nanoparticles (NPs), such as titanium dioxide (TiO2), have been recently considered. This research investigated the effects of a well - dispersed form of TiO2 NPs on autophagic vesicle formation in human melanoma A375 cells. The cells were treated with different concentrations of TiO2 NPs (1 - 100 µg/mL) for 24 hours, then growth, cell death, and autophagy were, respectively, evaluated by trypan blue exclusion test, MTT assay, and acridine orange staining. The results showed that well - dispersed TiO2 NPs induced growth inhibition in a dose dependent manner, while cell death was only observed at high concentrations (100 µg/mL). In addition, a significant increase in Acidic Vesicular Organelles (AVO) formation was detected at all concentrations of NPs after 24 hours, suggesting that TiO2 NPs may induce both cytostatic and cytotoxic autophagic responses, depending on the concentration.

Effect of gelatin/agar bilayer film incorporated with TiO2 nanoparticles as a UV absorbent on fish oil photooxidation

AbstractThis research evaluated the effect of gelatin/agar bilayer film and nanocomposites containing different concentrations of TiO2 nanoparticles (0.5%, 1% and 2%) as ultraviolet (UV) and oxygen barriers on the oxidative stability of fish oil. Samples of fish oil covered with the bilayer films were stored under UV light or in darkness and with or without lids at 18 °C for 12 days. Oil quality in terms of peroxide values (PV), thiobarbituric acid (TBA), conjugated diene (CD), fatty acids profile and colour change (∆E) was monitored during storage. Fish oil photooxidation was hindered by increasing TiO2 concentration, so that nanocomposite containing 2% of the nanoparticles could control photooxidation, similar to the samples stored in darkness. Furthermore, upon studying both photooxidation and autoxidation, the highest amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), as well as the lowest amount of changes in PV, TBA, CD and ∆E, were observed in oils covered with the nanocomposites.

Superhydrophobic dual layer functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PH) nanofibrous membrane for high flux membrane distillation

In this study, superhydrophobic dual layer membranes with highly porous structure were fabricated using electrospinning and electrospraying techniques. Electrospinning method was used to produce the support nanofibrous layer using polyvinylidene fluoride-co-hexafluoropropylene (PH) as the polymer and a mixed solvent system of N,N-Dimetylformamide (DMF) and acetone. Afterwards, hydrophobic, functionalized TiO2 nanoparticles were deposited on the surface of the support layer using the electrospraying technique. TiO2 chemical functionalization and their deposition on the support layer were investigated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy. The effects of different concentrations of TiO2 nanoparticles (100 and 200wt%) and PH (7–9wt%) in the electrospraying solution on the dual layer membrane characteristics, such as surface morphology, pore size, porosity, water contact and sliding angle, mechanical properties, and liquid entry pressure (LEP) were thoroughly examined. The results show that porous superhydrophobic nanofibrous membranes with water contact angles higher than 150°, sliding angles lower than 10°, and low contact angle hysteresis were successfully fabricated. Consequently, the prepared membranes showed comparable LEP with the commercial polyvinylidene fluoride (PVDF) membrane, but at much higher porosity (>85%) and mean pore size (>0.70μm). Performance of the dual layer membranes, along with the single layer PH and commercial PVDF membranes, were carried out in a direct contact membrane distillation setup. The superhydrophobic nanofibrous membrane showed noticeably more stable operation compared with the neat PH membrane and consistently higher flux (38.71∓1.105Lm−2h−1) than the commercial PVDF membrane (26.64∓0.97Lm−2h−1) during 24h of operation.

Effects of adding TiO2 nanoparticles to a water-based varnish for wood applied to nine tropical woods of Costa Rica exposed to natural and accelerated weathering

The addition of titanium dioxide nanoparticles (TiO2 nanoparticles) to a water-based varnish used for finishing tropical woods was studied. Three different concentrations of TiO2 nanoparticles (0%, 1.0%, and 1.5%) were evaluated. The nanoparticles were characterized by means of the transmission electron microscopy and an X-ray diffractometer. The varnish prepared was evaluated for its viscosity, adhesion of the film to the wood, water absorption, and the effects of natural weathering on the color and quality of the varnish. It was found that viscosity decreases as the concentration of TiO2 nanoparticles increases, while no variation was found in the thickness of the film. Except for Gmelina arborea and Tectona grandis, the adhesion was not statistically affected. It was found that, in the 9 species tested, incorporation of TiO2 nanoparticles decreased the values of water absorption. The evaluation of natural weathering showed that the varnish with no added TiO2 nanoparticles degraded completely after 1 year of weathering exposure, while the modified varnish film endured. Less color change was observed in lumber treated with the varnish containing TiO2 nanoparticles. The best performance of the varnish in the nine tropical woods used was observed when TiO2 nanoparticles were added at 1.5% concentration.

Research on the physicochemical and tribological properties of nano-TiO2 in the aqueous rolling liquid

Aqueous rolling liquids with different concentrations of TiO2 nano-particles are prepared. The dispersing mechanism of nano-TiO2 in the rolling liquid is studied by FTIR and TEM. Wettability and viscosity of these rolling liquids is evaluated based on Dataphysics OCA50 contact angle measuring device and SYD-265C viscometer, respectively. New viscosity empirical formula that suitable for nano-TiO2 aqueous rolling liquid is proposed. The tribological property is also investigated by the MM-WIA universal tribological tester. The results indicate that with the increase in the nano-particle’s addition, the contact angle gradually decreases, whereas the viscosity rises, which would contribute to ameliorating the frictional behaviour of aqueous suspensions. The aqueous suspension with 0.7 wt% TiO2 possesses excellent friction reduction and anti-wear properties.

Reusability of photocatalytic TiO2 and ZnO nanoparticles immobilized in poly(vinylidene difluoride)-co-trifluoroethylene

Pollutants present in water are increasingly becoming an important public health issue. After their transportation across the sewer network they can pass through the wastewater treatment plants (WWTPs) mostly unchanged because WWTPs are not designed to remove pollutants present at trace levels. Conventional treatments are therefore ineffective. Immobilized photocatalytic systems are thus an advantage for the treatment of contaminated water, because they are ecofriendly, cost-effective and allow reusability. This work reports on TiO2 and ZnO commercial nanoparticles immobilized in poly(vinylidene difluoride)-co-trifluoroethylene (P(VDF-TrFE)). Nanocomposites of P(VDF-TrFE) with different concentrations of TiO2 nanoparticles (5, 10, and 15wt.%) and ZnO nanoparticles (15wt.%) were produced by solvent casting and tested on the degradation of methylene blue, a model organic dye. Each nanocomposite was tested three times to assess its reusability. It is shown that increasing the photocatalyst concentration results in higher photocatalytic efficiencies; the degradation rates of 15% of TiO2 and ZnO are similar; and the photoactivity decreases 6%, 16%, 13%, and 11% after three utilizations, for TiO2 5%, TiO2 10%, TiO2 15%, and ZnO 15%, respectively. Thus, the low decrease in the photocatalytic activity after three uses makes the nanocomposites suitable for applications in which reusability is an important key factor.

EFFECT OF TIO2 NANOPARTICLES SPRAYING ON FENNEL PLANT

The present investigation was carried out to investigate effects of TiO2 nanoparticles on growth and chemical composition of fennel plants . Previous work showed that TiO2 nanoparticles could significantly raise photosynthesis and greatly improve growth of fennel (Feoniculum vulgare Mill) plants . The plants were sprayed with different concentrations of TiO2 nanoparticles 2, 4 and 6 ppm . The results showed that, TiO2 nanoparticles at treatment 6 ppm could obviously get the highest number of branches , the tallest plants , the highest fruit yield per plant and the highest values of Pigments,Carbohydrates, phosphorus ,Sugars nitrogen , potassium . sprayed fennel plant with concentrations of TiO2 nanoparticles 0, 2, 4 and 6 ppm is safe for human .

Effect of different concentration of TiO2 nanoparticles in phenosafranin dye-based organic photovoltaic device

In this work, the influence of concentrations of TiO2 nanoparticles on the performance of phenosafranin-based organic photovoltaic devices has been studied. Different photovoltaic cells based on phenosafranin dye have been prepared with different concentrations of TiO2 nanoparticles. The photocurrent density is observed to be 0.438 μA/cm2 without nanoparticles, whereas it becomes 2.58 μA/cm2 when TiO2 nanoparticle is added to phenosafranin. The photocurrent and the efficiency of the device increase initially with the concentration of the nanoparticle and then decrease. It is observed that the open-circuit voltage does not vary significantly with the concentration of the nanoparticles. It is also observed that the absorption spectra changes with the concentration of the nanoparticles. The absorption peak does not change, but the width of the spectra changes with the increase in concentration of nanoparticles.

The effect of UV irradiation on PSf/TiO2 mixed matrix membrane for chromium rejection

The study investigated a novel approach for surface modification of membranes and sustainable water recovery from chromium contaminated water by employing a lab scale dead-end cell filtration unit. Various PSf/TiO2 composite membranes prepared with different concentrations of TiO2 nanoparticles were exposed to UV radiations for surface modification. On exposure to UV light, TiO2 nanoparticles emit electrons and create a surface roughness with a charge on the membranes which resulted in enhanced chromium rejection as well as flux. The surface modification has been analyzed by AFM and SEM (surface and cross sectional) images. The structural modification was investigated by ATR-IR and UV–Visible spectroscopy. The expected enhancement in hydrophilicity was studied by water uptake and contact angle measurements. The analysis of water flux and chromium rejection performed in a dead end filtration unit revealed a high water flux and 100% chromium rejection with 2wt.% of TiO2 composite membrane in acidic pH. The pH of feed plays an important role in chromium rejection. The rejection of chromium decreases with an increase in feed concentration due to the variation in ion distribution. The effect of interference of other metals in chromium rejection is investigated. The overall work not only demonstrates the positive effects of surface modification, but also effective removal of hazardous chromium.

Synthesis and design of PSf/TiO2 composite membranes for reduction of chromium (VI): Stability and reuse of the product and the process

Abstract

Photo-induced inhibitory effect of titanium dioxide nanoparticles on a human epidermal squamous cell carcinoma cell line A431

Objective To evaluate the inhibitory effect of photocatalytic titanium dioxide （TiO2）on the growth of a human epidermal squamous cell carcinoma cell line A431 and its mechanism. Methods Cultured A431 cells were classified into various groups to remain untreated （blank control group）, be treated with different concentrations （100, 200, 300, 400, 500, 600 mg/L） of TiO2 nanoparticles alone or in combination with ultraviolet （UV, main wavelength 253.7 nm, power 30 W, distance 30 cm, exposure duration 15 min） irradiation. After additional culture for different durations, methyl thiazolyl tetrazolium （MTY） assay was performed to evaluate cell growth, annexin V-fluorescein isothiocyanate/propidium iodide （PI） double staining to observe cell apoptosis, and Rho123 staining to determine mitochondrial transmembrane potential. Statistical analysis was earried out using SPSS 13.0 software. Analysis of variance （AOV）, t test and Student-NewmanKeuls （SNK） test were performed to assess the differences in these parameters between these groups. Results The growth of A431 cells was inhibited by pretreatment with TiO2 nanoparticles followed by UV irradiation, and the inhibitory effect was enhanced as the dose of TiO2 nanoparticles increased. As AOV and SNK test showed, there were significant differences in the growth inhibition rate among A431 cells treated with different concentrations of TiO2 nanoparticles at the three time points （24, 48 and 72 hours） after UV irradiation （n = 6, F = 21.54, 77.56, 20.27, respectively, all P 〈 0.05）. No statistical inhibition was observed in the growth of A431 cells treated with TiO2 nanopartieles alone compared with untreated A431 cells （all P 〉 0.05）. Photocatalytie TiO2 nanoparticles also induced the apoptosis but decreased the mitochondrial transmembrane potential in A431 cells. In detail, theapoptosis rate was 8.86% ± 0.22%, 11.72% ± 0.29% and 31.24% ± 0.78% in A431 cells treated with Ti02 nanoparticles of 100, 200, 400 mg/L followed by UV irradiation, respectively, compared to 2.69% ± 0.28% in the blank control group （n = 3, F = 256.61, P 〈 0.05）. Decreased mitochondrial transmembrane potential （expressed as total fluorescence intensity） was observed in A431 cells treated with Ti02 nanoparticles of 100, 200, 400 mg/L followed by UV irradiation compared with blank control group （758.48 ± 15.42, 676.60 ± 14.35, 557.71 ± 13.12 vs. 2943.65 ± 70.26, F = 208.57, P 〈 0.05, n = 3）, and SNK test also revealed statistical differences between these groups. Conclusions Ti02 nanoparticles combined with UV can inhibit the growth of but induce the apoptosis in A431 cells, which may be associated with the reduction in mitoehondrial transmembrane potential in A431 cells, while Ti02 nanoparticles alone show no inhibitory effect on the growth of A431 cells. Key words: Carcinoma, squamous cell; Nanocomposites; Cell line, tumor; Ultraviolet rays; Apoptosis; Membrane potential, mitochondrial

Spectroscopic studies of photodegradation of polyethylene films containing TiO2 nanoparticles

AbstractThe effect of UV radiation on a family of low density polyethylene films containing different concentrations of TiO2 nanoparticles has been studied. The photodegradation was monitored using FTIR measurements of carbonyl group development and an in situ FTIR method that tracks the generation of CO2 as a principal product of degradation. Samples containing dispersant and/or a phenolic antioxidant but free from TiO2 particles were examined as controls. It was shown that the effects of photodegradation of the polymers could be followed even when these additives were present. The dispersant gave rise to absorption in the carbonyl region of the IR spectrum but meaningful results concerning the progress of photodegradation were obtained using difference spectra. Good correlation was found between the carbonyl and the CO2 measurements of the relative photosensitivities of the films with different compositions, and both methods indicated that addition of the nano‐particulate rutile TiO2 had decreased the film photostability. The decreased photostability inferred from spectroscopic measurements was also observed as a reduction, from ∼ 1100 h to 400 h, of the exposure time before film cracking, when samples were exposed to UVA radiation in QUV equipment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Electrodeposition and characterization of Cu-TiO2 nanocomposite coatings

Cu-TiO2 nanocomposites were prepared by electrodeposition method onto copper substrate using an acid copper plating bath containing dispersed nanosized TiO2. The composition of codeposited TiO2 nanoparticles in the composite coatings was controlled by the addition of different concentrations of TiO2 nanoparticles in the bath solution. The average crystallite size was calculated by using X-ray diffraction analysis and it was ~32 nm for electrodeposited copper and ~33 nm for Cu-TiO2 composite coatings. The crystallite structure was fcc for electrodeposited copper and Cu-TiO2 nanocomposite coatings. The surface morphology and composition of the nanocomposites were examined by scanning electron microscopy and energy dispersive X-ray spectroscopy analysis. The effect of TiO2 content on the corrosion and wear resistance properties of the nanocomposite coatings was also presented. The codeposited TiO2 nanoparticles in the deposit increased the corrosion and wear resistance, which were closely related with TiO2 content in the nanocomposites. The wear resistance and microhardness of the Cu-TiO2 nanocomposite coatings were higher than electrodeposited copper. The corrosion resistance property of the electrodeposited copper and Cu-TiO2 nanocomposite coatings was evaluated by electrochemical impedance and Tafel polarization studies. Cu-TiO2 composite coatings were more corrosion resistant than electrodeposited copper.

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SiO2 nanofluids are advanced nanomaterials in which SiO2 nanoparticles (NPs) due to high specific surface area and dispersion stability may provide promising possibilities for various applications including their use for oilfield industries. However, SiO2 NPs (being solid charged particles) tend to aggregate and form NP clusters which are subjected to prematurely settle with time thus, rendering unstable and rheologically damaged nanofluid. In this work, a nanoparticle viz., TiO2 (∼50 nm) with concentration of 0.05 and 0.1 wt% was tested as co-stabilizer to improve the stability of SiO2 nanofluid [0.5 wt% SiO2 in base of polyacrylamide (PAM), called SN nanofluid] via reducing the homoaggregation and rate of sedimentation (ROS). SN nanofluid prepared using 0.5 wt% SiO2 in the presence of different concentrations of TiO2 NPs (0.05 and 0.1 wt%), called STN nanofluids, was also analyzed by dispersion stability, SEM, EDS, DLS, UV–vis, electrical conductivity, and rheological studies. Compared to SN nanofluid (dispersion stability ≈6 weeks), STN nanofluids exhibited enhanced dispersion stability of more than 10 weeks with reduced size of NP aggregates, consistent with SEM and EDS results. Electrical conductivity and UV–vis results support that SiO2 aggregates in presence of TiO2 remain suspended for longer time than sole SiO2 aggregates as witnessed by improved absorbance and electrical conductivity. Moreover, the effect of shear deformation on rheological properties (viscosity and viscoelastic moduli) of STN nanofluids was marginal than SN nanofluid, mainly due to the presence of TiO2 NP which in presence of SiO2 collectively formed nanocomposites of SiO2-TiO2 which controlled the properties of nanofluid. The study highlighted important aspects of colloidal suspensions and is a forward step towards the use of SiO2 based nanofluid for industrial applications.