Effects Of nano-TiO2 Research Articles

Space charge characteristics of LDPE nanocomposite/LDPE insulation system

Two kinds of insulation systems with nanocomposite have been fabricated by co-pressing low-density polyethylene (LDPE) and nano-titania doped LDPE (TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -LDPE) films. The three-layer systems considered are TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -LDPE/LDPE/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -LDPE (namely, NLN) and LDPE/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -LDPE/LDPE (namely, LNL). Space charge distributions under different applied electric fields were measured by the pulsed electro acoustic (PEA) method. The charge transport characteristics and the interface space charge formation as well as the effect of nano-TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> concentration have been systematically discussed. The results show that heterocharges and homocharges are formed at the LDPE/TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -LDPE polymer interfaces in the system NLN and LNL, respectively. The nature of the interfacial charge has been explained in term of the interfacial polarization theory combined with conductivity and permittivity of the materials. Additionally, the recombination between charges influences the amount of the interface space charge. However, the NLN system always stores more charges than LNL, which was explained by the change of the effective electric field caused by the formation of the interface space charges. The results obtained would provide experimental support for optimizing high voltage direct current power cables.

Effects of Nano-TiO2on the Toughness and Durability of Cement-Based Material

The effects of nano-TiO2(NT) on microstructures and mechanical properties of cement mortars were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and mercury intrusion porosimetry (MIP). Results show that 3% NT can remarkably increase the tensile/flexural strengths (i.e., the toughness is improved) and promote the precipitation of AFt crystal. The flexural and tensile strengths have significant positive correlation to the formation amount of AFt. The pores of mortars can be significantly refined and shift to harmless pores by controlling the growth of CH crystal and increasing the hydration reaction rate. The durability of cement-based materials is discussed by testing their water absorption and water-vapour permeability. Results show that the addition of 3% NT can decrease the water absorption ratio by 40–65%, water absorption coefficients by more than 40%, and water-vapour permeability coefficients by 43.9%, indicating that 3% NT can effectively improve the compactness and durability of cement-based materials.

Composite-porous polymer membrane with reduced crystalline for lithium–ion battery via non-solvent evaporate method

Nano-TiO2 is selected as inorganic filler to fabricate the reduced crystalline composite polymer membrane. The porous polymer matrix employed in this study was poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) membrane synthesized via non-solvent evaporate method and the electrolyte solution uptake was carried out in the glove box to avoid the moisture contamination. The effect of nano-TiO2 on the crystalline of porous polymer membrane was studied. It was found that blending with nano-TiO2 helps to reduce the crystalline of polymer membrane. Electrochemical impedance spectroscopy showed that the room temperature conductivity of PVDF-HFP/TiO2 composite-porous polymer electrolyte (CPPE) increased up to 1.5 × 10−3S/cm, and scanning electron microscope (SEM) micrographs showed that the micro-pores and nano-TiO2 particles were observed in the polymer membrane. Furthermore, the composite-porous polymer electrolyte was stable up to 4.5 V (vs. Li/Li+) and the LiFePO4/CPPE/Li coin cell showed excellent rate capability, the discharge capacity obtained at 0.1C, 0.5C, 1C, and 3C were 164, 157, 143, and 122 mAh/g, respectively. And the cell had about 6 % capacity loss when it discharged at 1C for 50 cycles.

Effects of nano-TiO2 on strength, shrinkage and microstructure of alkali activated slag pastes

For alkali-activated slag (AAS), high drying shrinkage is an obstacle which impedes its application as a construction material. In this investigation, nano-TiO2 was added to AAS, and its mechanical properties and shrinkage were tested to examine its effect on hardened alkali-activated slag paste (AASP). To understand the impact of nano-TiO2 on AASP at micro scale, FTIR, MIP and SEM were carried out. Experimental results indicate that the addition of nano-TiO2 to AAS enhances the mechanical strength, and decreases the shrinkage of AASP. FTIR and SEM results demonstrated that the addition of nano-TiO2 into the AASP accelerates its hydration process, resulting in more hydration products and denser structure. MIP results showed that the addition of nano-TiO2 reduces the total porosity of AASP and changes the pore structure. The porosity of 1.25–25nm mesopores, which is believed to be responsible for the high shrinkage of AASP, is remarkably reduced due to the addition of nano-TiO2.

Effects of nano-TiO2 and normal size TiO2 additions on the microstructure and magnetic properties of manganese–zinc power ferrites

The effects of nano-TiO2 and normal size TiO2 additions on the microstructure and magnetic properties of manganese–zinc (Mn–Zn) power ferrites were investigated, respectively. It is found that the magnetic properties of Mn–Zn power ferrites can be improved with a suitable amount of nano-TiO2 or normal size TiO2 addition. At 100°C, compared to the reference sample without nano-TiO2 addition, the sample with 0.05wt% nano-TiO2 addition shows a more uniform grain structure and a decrease of 9.63% in power loss (PL) to 394kW/m3. In this case, the initial permeability of sample declines by 0.3%, compared to that of the sample with 0.03wt% nano-TiO2 addition. Besides that, at 100°C, when the normal size TiO2 concentration increases gradually to 0.07wt%, the PL of sintered samples decreases monotonously to 315kW/m3. In the temperature range of 90–120°C, the PL of the sample with 0.07wt% normal size TiO2 addition are lower than 330kW/m3. It is indicated that the optimal content of normal size TiO2 is higher than 0.07wt%. The thermal stability of sintered sample can be considerably improved with a suitable amount of nano-TiO2 or normal size TiO2 addition.

Electrochemical performance of TiO 2 /Au/carbon nanotubes composite interface for hydroquinone detection

A novel nanocomposite was prepared by direct mixing of titania nanoparticles (nano-TiO2) and gold nanoparticles (nano-Au)-modified carbon nanotubes (CNTs) in a solution of chitosan. The electrochemical performance of a TiO2/Au/CNT nanocomposite-modified electrode for hydroquinone detection was investigated. When measured at a scan rate of 50 mV s− 1, the detected amount of hydroquinone at the TiO2/Au/CNT electrode varied linearly with hydroquinone concentration, for concentrations from 1 × 10− 6 to 1 × 10− 8 M; the sensitivity was 997 617 μA(mol l− 1)− 1, and the detection limit was 1 × 10− 10 M (S/N = 3). In all experiments, TiO2/Au/CNT nanocomposites exhibited better electrochemical performance than TiO2/CNT composites or CNTs. Enhanced current response can be attributed to the synergic effect of nano-TiO2, nano-Au and CNTs.

Functional analysis of TiO2 nanoparticle toxicity in three plant species.

Titanium dioxide nanoparticles (nano-TiO2) are manufactured and used worldwide in large quantities. However, phytotoxicity research on nano-TiO2 has yielded confusing results, ranging from strong toxicity to positive effects. Therefore, in this research, the effects of nano-TiO2 on the germination and root elongation of seed and seedlings were studied. Additionally, the uptake and physiological responses of mature plants were investigated. Physical chemistry data were analyzed to assess the availability of nano-TiO2. Finally, a hydroponic system designed to overcome nano-TiO2 precipitation was used to reproduce the environmental conditions of actual fields. Nano-TiO2 did not have any effect on seed germination or on most of the plant species tested. Nano-TiO2 had positive effects on root elongation in some species. No physiological differences in enzyme activities or chlorophyll content were detected, even though the plants absorbed nano-TiO2. Physical chemistry data showed that nano-TiO2 agglomerated rapidly and formed particles with much bigger hydrodynamic diameters, even in distilled water and especially in a hydroponic system. Furthermore, agglomerated nano-TiO2 formed precipitates; this would be more severe in an actual field. Consequently, nano-TiO2 would not be also readily available to plants and would not cause any significant effects on plants. Our results and other reports suggest that titanium itself is not phytotoxic, even though plants absorb titanium. In conclusion, nano-TiO2 is not toxic to the three plant species, in vitro or in situ.

Study of photosynthetic pigments changes of maize (Zea mays L.) under nano Tio2 spraying at various growth stages

Tests were done on the effects of treatments of titanium dioxide spray on corn (Zea mays L.). The study was conducted as a factorial experiment in a randomized complete block design with four replications. Treatments consisted of two factors; the first factor was stage of plant growth that spraying was applied (vegetative stage, appearance of male flowers and female flowers); and the second factor was that of different concentrations of titanium dioxide nanoparticles (Tio2) that consisted of spray with water (control), titanium dioxide or bulk, nano titanium dioxide at concentrations of 0.01% and 0.03%. Results showed that effect of nano Tio2 was significant on chlorophyll content (a and b), total chlorophyll (a + b), chlorophyll a/b, carotenoids and anthocyanins. The maximum amount of pigment was recorded from the treatment of nano Tio2 spray at the reproductive stage (appearance of male and female flowers) in comparison with control. Thus, an application of nanoparticles (nanao Tio2) can facilitate an increase in crop yield, especially corn yield.

Effects of nano-TiO2 on combustion and desulfurization

Nanosized titanium oxide powder was prepared via the sol–gel process and characterized by transmission electron microscope. The effects of nano-TiO2 on combustion characteristics of lignite, desulfurization in combustion and the properties of ashes were investigated. The calorific value of coals and the fusion point of the coal ashes were measured by calorimeter and ash fusion point determination meter; the components of coal ashes and the contents of combustible matters in ash were determined by chemical methods; the pore-size distribution and specific surface area of the coal ash were analyzed by surface area analyzer. A thermogravimetric analyzer was used to investigate the effect of nano-TiO2 on combustion. The results showed that the calorific value of the coal and the fusion temperature of the coal ash were lowered by adding CaO, while on the other hand adding nano-TiO2 to coal increased the calorific value and the melting temperature effectively. Meanwhile, the coal combustion efficiency and desulfurization in combustion could be effectively improved by the co-action of TiO2.

Effects of nano-TiO2 on photosynthetic characteristics of Ulmus elongata seedlings

The physiological and ecological responses of Ulmus elongata to different concentrations of nano-anatase TiO2 solutions were investigated in this study and we found that with foliar application of 0.1% (T1), 0.2% (T2) and 0.4% (T3) nano-anatase TiO2 solution the net photosynthetic rate of U. elongata seedlings were lower, comparing with the control (CK) (no spraying). TiO2 solution had no effect on the carbon isotope values (δ13C), indicating the lower photosynthetic capacity was not caused by stomatal limitation. The nitrogen isotope values (δ15N) decreased, but the foliar metal elements, such as Mg, K and Mn contents were not affected by nano-anatase TiO2 which promoted the Cu uptake. Fourier transform infrared spectroscopy showed that the nano-anatase TiO2 enhanced the absorbance of U. elongata leaves, especially for 1064, 1638, 2926 and 3386 cm−1 bands, indicating the synthesis of carbohydrate and lipid compounds was a kind of mechanism under the toxic effects of nanonanoparticles.

Preparation and characterization of PSA/nano-TiO2 composites and fibers

Polysulfonamide/nano titanium dioxide (PSA/nano-TiO2) composite spinning solutions with various nano-TiO2 mass fractions were prepared using the solution blending method. The corresponding composite fibers were developed by wet-spinning technology and the composite membranes were prepared using the digital spin-coating technique. The properties of PSA/nano-TiO2 composite fibers and membranes were investigated by scanning electron microscope, Fourier transform infrared spectroscopy and X-ray diffraction, etc. The effects of nano-TiO2 and its mass fractions on the mechanical properties, thermal stability and ultraviolet resistance of PSA composites were also analyzed. The experimental results showed that nano-TiO2 with low mass fractions can be dispersed evenly in the PSA matrix; the blending of nano-TiO2 had no obvious influence on the molecular structure and the chemical composition of PSA fiber; the crystallization in PSA fiber was promoted at low nanoparticles mass fractions because it can act as a nucleation agent; the mechanical properties and the thermal stability of PSA/nano-TiO2 composites can be enhanced obviously by blending nano-TiO2 into PSA matrix. The ultraviolet resistance of PSA composites can be improved significantly with the increasing nano-TiO2 mass fractions and the 7 wt.% specimen showed the lowest UV transmittance.

Effect of nano-TiO2 on the polarization process of polyimide/TiO2 composites

Polyimide/TiO2 composite films have been successfully prepared by in-situ dispersive polymerization. The cross section surface morphology, film composition, electrical conductivity and dielectric properties of the composite films are characterized. The results show that inorganic TiO2 nanoparticles are well dispersed in the polymer matrices. We observed that polyimide/TiO2 composites exhibit lower relative permittivity at low TiO2 doping concentration (0–3%) compared to a pure polyimide; and exhibit higher relative permittivity at higher TiO2 doping concentrations (>5%); dielectric loss (loss tangent) is enhanced at frequencies <10Hz and reduced at frequencies >104Hz as TiO2 doping concentration increases. TiO2 nanoparticle doping brings space-charge polarization to composite matrices through enhanced charged carrier generation. At the same time, TiO2 nanoparticle doping sites act as pinning mechanism to reduce polymer chain motion in orientation polarization. The interplay of these two polarization processes determines the dielectric property changes that we observed on polyimide/TiO2 composites.

Titanium dioxide nanoparticles activate the ATM-Chk2 DNA damage response in human dermal fibroblasts

The use of nanoparticles in consumer products increases their prevalence in the environment and the potential risk to human health. Although recent studies have shown in vivo and in vitro toxicity of titanium dioxide nanoparticles (nano-TiO2), a more detailed view of the underlying mechanisms of this response needs to be established. Here, the effects of nano-TiO2 on the DNA damage response and DNA replication dynamics were investigated in human dermal fibroblasts. Specifically, the relationship between nano-TiO2 and the DNA damage response pathways regulated by ATM/Chk2 and ATR/Chk1 was examined. The results show increased phosphorylation of H2AX, ATM, and Chk2 after exposure. In addition, nano-TiO2 inhibited the overall rate of DNA synthesis and frequency of replicon initiation events in DNA-combed fibres. Taken together, these results demonstrate that exposure to nano-TiO2 activates the ATM/Chk2 DNA damage response pathway.

Toxicological effects of nanometer titanium dioxide (nano-TiO2) on Chlamydomonas reinhardtii

The toxicological effects of nanometer titanium dioxide (nano-TiO2) on a unicellular green alga Chlamydomonas reinhardtii were assessed by investigating the changes of the physiology and cyto-ultrastructure of this species under treatment. We found that nano-TiO2 inhibited photosynthetic efficiency and cell growth, but the content of chlorophyll a content in algae did not change, while carotenoid and chlorophyll b contents increased. Malondialdehyde (MDA) content reached maximum values after 8h exposure and then decreased to a moderately low level at 72h. Electron microscopy images indicated that as concentrations of nano-TiO2 increased, a large number of C. reinhardtii cells were noted to be damaged: the number of chloroplasts declined, various other organelles were degraded, plasmolysis occurred, and TiO2 nanoparticles were found to be located inside cell wall and membrane. It was also noted that cell surface was surrounded by TiO2 particles, which could present an obstacle to the exchange of substances between the cell and its surrounding environment. To sum up, the effect of nano-TiO2 on C. reinhardtii included cell surface aggregation, photosynthesis inhibition, lipid peroxidation and new protein synthesis, while the response of C. reinhardtii to nano-TiO2 was a rapid process which occurs during 24h after exposing and may relate to physiological stress system to mitigate damage.

In Vitro Influences of TiO2 Nanoparticles on Barley (Hordeum vulgare L.) Tissue Culture

In the last decades, extensive research on the effects of nano-TiO₂ on plant systems and different microorganisms has confirmed its photocatalytic and antimicrobial activity. However, there is no report on its application in plant cell and tissue culture as well as its role in eliminating contaminating microorganisms in tissue culture. In this work, barley mature embryos were cultured in Murashige and Skoog medium with four concentrations (0, 10, 30, 60 μg/ml) of TiO₂ suspension in four repetitions. Quantitative and qualitative characteristics of calli were analyzed after each subculture. Data analysis for calli number in the first culture and callus size in all three cultures showed that the effect of treatment was significant at p > 0.95. As a result, quantitative features such as callus color, shape, embryogenesis, etc. were completely similar in both control and TiO₂ nanoparticle treatments; there is no doubt that TiO₂ nanoparticles could dramatically increase callugenesis and the size of calli. As well, TiO₂ nanoparticles are effective bactericides with an aseptic effect, causing no negative change in the quality of the callus. It is necessary to do more complementary works to identify mechanisms involved for the increased calli size and embryogenesis of explants in darkness.

Research on Application of Nano-TiO&lt;sub&gt;2&lt;/sub&gt; in Automotive Coating

In this article, the mechanism of the effects of nano-TiO2 on the properties of automotive topcoat is discussed. Based on the original thought that nano-TiO2 may improve the aging property, a research is carried out into the effects of nano-TiO2 on the properties of automotive topcoat, and the formulation design of nano-TiO2 coating is optimized. The coating properties such as glossiness, adhesion, resisting impact strength, hardness, water fastness and resistance to aging are measured by experiments. The results show that with 1.0~2.0 percent of nano-TiO2 content, the aging resistance of the coating increases by approximaSubscript texttely 20 percent with higher glossiness, while adhesion, impact strength, hardness and water fastness are not meaningfully improved.

Characterization and Thermal Decomposition Kinetics of Poly(ethylene 2,6-naphthalate) Nanocomposites Reinforced with TiO2 Nanoparticles

Poly(ethylene 2,6-naphthalate) (PEN) reinforced with TiO2 nanoparticles (nano-TiO2) were prepared by direct melt compounding. Thermogravimetric analysis was conducted on the PEN/nano-TiO2 nanocomposites to clarify the effect of nano-TiO2 on the thermal decomposition behavior of the resultant nanocomposites. There is a significant dependence of thermal decomposition behavior for PEN/nano-TiO2 nanocomposites on the content of nano-TiO2 and heating rate. The variation of the activation energy for thermal decomposition reflected the improvement of the thermal stability of the PEN/nano-TiO2 nanocomposites. The incorporation of nano-TiO2 into the PEN matrix increased the storage modulus of the PEN/nano-TiO2 nanocomposites.

Effect of nano-TiO2 on the mechanical properties of cement mortar

Effect of nano-TiO2 on the mechanical properties of cement mortar was studied in this paper. Test results indicated that when cement was substituted by nano-TiO2, the strength of cement mortar at early ages increased a lot and the fluidity and strength at evening ages decreased obviously. The change tendency of diffraction intensity of (001) crystal plane was entirely different with that of (101) crystal plane. It seemed that the main reason for the improvement of strength is the decrease and modification of orientation index for the nucleus function, not the increasing amount of hydration products. Results also indicated that it was useful to modify the fluidity and the strength at evening ages of the cement mortar with nano-TiO2 by adding superplasticizer and slag powder into cement mortar.

Nano-TiO2 Enhanced Photofermentative Hydrogen Produced from the Dark Fermentation Liquid of Waste Activated Sludge

After anaerobic dark fermentation of waste activated sludge (WAS) for hydrogen production, there are a large number of organic compounds including protein, polysaccharide, and volatile fatty acids left in the dark fermentation liquid, which can be further bioconverted to hydrogen by photofermentation techniquea. In this study, the enhancement of photofermentative hydrogen produced from WAS dark fermentation liquid by using nano-TiO2 is reported. First, high concentration of NH(4)(+)-N in the dark fermentation liquid was observed to inhibit the photofermentative hydrogen production, and its removal was essential. Then the effect of nano-TiO2 on photofermentative hydrogen generation was investigated, and the addition of 100 mg/L nano-TiO2 increased hydrogen by 46.1%. Finally, the mechanisms for nano-TiO2 improving hydrogen production were investigated. It was found that nano-TiO2 improved the decomposition of protein and polysaccharide to small-molecule organic compounds and promoted the growth of photosynthetic bacteria and the activity of nitrogenase but decreased the H2-uptake hydrogenase activity.

Curing of polyester powder coating modified with rutile nano-sized titanium dioxide studied by DSC and real-time FT-IR

Polyester powder coating modified with 2 mass% of rutile nano-sized titanium dioxide (nano-TiO2) was prepared by melt-blend extrusion method. The nano-TiO2 dispersion state in the powder coating matrix was analyzed by field emission scanning electron microscopy (FE-SEM), which presented a well dispersion of modified nano-TiO2 in the polyester powder coating. The effect of nano-TiO2 on the curing of polyester powder coating was investigated by differential scanning calorimeter (DSC). Kissinger and Crane methods were used to study the activation energy (E) and reaction order (n) of the coating. The results indicated that 2 mass% of nano-TiO2 additive played a prompting role in the curing of polyester powder coatings, due to the hydroxyl functional groups existed on the surface of nano-TiO2. Furthermore, real-time Fourier transform infrared (FT-IR) spectroscopy with a heating cell was also employed to record the curing actions, of which results were consistent with the DSC experiments.