Presence Of TiO2 Nanoparticles Research Articles

Effect of Adding TiO2 Nanoparticles to a Lubricant Containing MoDTC on the Tribological Behavior of Steel/Steel Contacts Under Boundary Lubrication Conditions

The tribological performance of lubricants containing TiO2 nanoparticles and Molybdenum DiThioCarbamate (MoDTC) was investigated using a reciprocating ball-on-flat tribometer in steel–steel contacts. Lubricants containing only MoDTC were used for comparison. The influences of the additive concentration (0.1 wt% and 0.5 wt%) and of the roughness of the counterparts (Ra from 10 to 200 nm) on the performance of the lubricant were studied. Improved friction modification and anti-wear properties were found when TiO2 nanoparticles were blended with MoDTC compared to MoDTC alone, even at low concentration and with rough surfaces. XPS characterizations and FIB-TEM analyses of tribofilms were performed and suggested that the formation of MoS2 from MoDTC is favored in the presence of TiO2 nanoparticles. The results are discussed, taking into account the tribocatalytic properties of TiO2 nanoparticles.

Removal of micro-pollutant using an indigenous photo membrane reactor

Pharmaceutical wastewater treatment using heterogeneous photocatalysis in presence of TiO2 nanoparticles has become a lucrative method because the convectional wastewater and biological treatments usually fail to remove the detrimental effect of different drugs and hormones on the environment. The nanoparticles recovery and reuse is the most challenging task in practice. The main goal of the present study is to recover and reuse of photocatalyst by immobilizing it on the membrane surface. Consequently, two types of immobilization technique have been used here, one is surface immobilization by dipped coating, and other is impregnation of catalyst during fabrication of the membrane. To conduct photocatalysis, an indigenous photo membrane reactor has also been fabricated during the research work. The presence of TiO2 nanoparticles has not only improved the catalytic property of the membrane, but also the contact angle analysis has confirmed the enhanced hydrophilic as well as antifouling property of the surface modified membrane. The fabricated membranes were characterized by scanning electron microscopy (SEM). To analyses the performance of photo membrane reactor as well as TiO2 coated or impregnated membranes, the photocatalytic degradation of aqueous solution of chlorhexidine digluconate (CHD), an antibacterial drug, was performed using the developed system and the removal percentage of CHD obtained from the system was found to be quite appreciable. The results show that the recovery and reuse of the catalyst by the present system is very much significant. Meanwhile, the developed reactor can be operated in cross flow configuration under batch, semi-batch and continuous mode.

Exogenous Nitric Oxide Improves the Protective Effects of TiO2 Nanoparticles on Growth, Antioxidant System, and Photosynthetic Performance of Wheat Seedlings Under Drought Stress

Drought stress is one of the most important environmental constraints that negatively affect crop growth and production worldwide. Recently, nanotechnology has increasingly been applied to improve tolerance in plants exposed to abiotic stresses such as drought. A pot experiment was conducted to examine the influence of nitric oxide donor sodium nitroprusside (SNP: 100 μM) in presence of TiO2 nanoparticles (TiO2 NPs: 500, 1000, and 2000 mg kg−1) on wheat seedlings under drought stress conditions. Water deficit negatively affected growth and photosynthetic parameters with simultaneous increase in activity of antioxidant enzymes. Under severe drought stress, soil-applied 2000 mg kg−1 TiO2 NPs enhanced seedling dry weight (DW), relative water content (RWC), catalase (CAT) activity, ascorbate peroxidase (APX) activity, and proline content. Moreover, 2000 mg kg−1 TiO2 NPs enhanced total chlorophyll (total Chl), carotenoids (Car), stomatal conductance (gs), and transpiration (E) under severe drought stress. However, addition of 100 μM SNP in presence of 2000 mg kg−1 TiO2 NPs significantly increased seedling length (SL), superoxide dismutase (SOD) activity, total soluble proteins, net photosynthetic rate (Pn), and intercellular CO2 concentration (Ci). The aforementioned treatment also significantly reduced hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents under severe drought stress. Our results suggest that foliar application of SNP in the presence of TiO2 NPs can protect wheat seedlings against drought-induced oxidative damage.

Microstructural analysis of Sn-3.0Ag-0.5Cu-TiO2 composite solder alloy after selective electrochemical etching

This work aims to provide deep morphological observation on the incorporated TiO2 nanoparticles within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry were used to investigate the selective etching performances. The removal of β-Sn matrix was conducted at a fixed potential of −350 mV. Average performances of 2.19 and 2.30 mA were attained from the chronoamperometry. The efficiency of β-Sn removal was approved according to the reduction of the intensities on the phase analysis. Successful observation of the TiO2 near the Cu6Sn5 layer was attained for an optimum duration of 120 s. Clusters of TiO2 nanoparticles were entrapped by Cu6Sn5 and Ag3Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO2 nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 IMC layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of the shape and size of the Cu6Sn5 and Ag3Sn. It was found that TiO2 content facilitates the β-Sn removal, which allows better observation of the IMC phases as well as the TiO2 reinforcement particles.

Genotoxicity of the food additive E171, titanium dioxide, in the plants Lens culinaris L. and Allium cepa L.

E171 (titanium dioxide, TiO2), an authorized foods and beverage additive, is also used in food packaging and in pharmaceutical and cosmetic preparations. E171 is considered to be an inert and non-digestible material, not storable in animal tissues, but the possible presence of TiO2 nanoparticles (NP) may present a risk to human health and the environment. We determined the presence of 15% TiO2 NP in a commercial E171 food additive product, by electron microscopy. The biological effects of E171 were assessed in Lens culinaris and Allium cepa for the following endpoints: percentage of germination, root elongation, mitotic index, presence of chromosomal abnormalities, and micronuclei. The results indicated low phytotoxicity but dose-dependent genotoxicity. We also observed internalization of TiO2 NP and ultrastructural alterations in the root systems.

Novel smart water-based titania nanofluid for enhanced oil recovery

Smart water application in carbonate reservoirs has been recently gained a lot of attention by researchers as a low-cost enhanced oil recovery (EOR) method. In this study, for the first time, the behavior of different smart waters in the absence and presence of TiO2 nanoparticles (NPs) has been investigated by analyzing their effect on wettability alteration, interfacial tension (IFT) reduction, and oil recovery improvement during the spontaneous imbibition process. The zeta potential analysis of TiO2 NPs in seawater (SW) shows a detrimental and insufficient effects of divalent cations (Ca2+ and Mg2+) and monovalent cations (Na+ and K+) on the nanofluid (NF) stability at a pH value higher than its point of zero charge (PZC), respectively, while the detrimental effect of divalent anions (SO42−) is observed at pH values lower than PZC. The results of contact angle measurements show a little improvement in the wettability alteration changing from modified SWs (MSWs) to diluted MSWs (dMSWs) and a significant improvement changing from dMSWs to dMSWs-based NF that is observed a diverse behavior for the IFT reduction, emphasizing the significant role of NPs addition to smart waters and decreasing the salinity of smart waters. During the imbibition experiments, the performance of all types of smart waters is drastically increased in the presence of TiO2 NPs confirming the results of contact angle experiments, occurred by their retention on the rock surface and movement through the porous media depending on the type of ions presented in the smart waters.

Combination of TiO2 nanoparticles and Echinometra mathaeis gonad extracts: In vitro and in vivo scolicidal activity against hydatid cysts

Abstract Echinococcosis (hydatid cyst) is a zoonotic disease in sheep, cattle, pigs, rats, and humans that is caused by larvae of the tapeworm Echinococcus granulosus. Several studies have shown that invertebrates exhibit activity against various parasites, but no studies are available of effects of extracts of the sea urchin Echinometra mathaei on hydatid cysts. Here, E. mathaeis gonad extracts were investigated for their effects on hydatid cysts, in the absence and presence of TiO2 nanoparticles. Different concentrations of E. mathaeis gonad extracts with and without TiO2 were applied for different times and the scolicidal activity of each of these conditions was determined on viable protoscolices. 15 μg/ml gonad extract + TiO2 was sufficient to kill 84% of the protoscolices after 60 min incubation. In vivo studies were performed on mice injected with E. granulosus protoscolices. Gonad extracts and gonad extracts combined with TiO2 were given by oral gavage for a period of 3 months. Combined application of extract and TiO2 increased the treatment efficiency, as shown by the reduction in number, size and volume of the cysts. Thus, sea urchin gonad extracts combined with TiO2 nanoparticles have anti-hydatic and scolicidal effects.

Solid-phase photocatalytic degradation of polyaniline under UVA and UVC light irradiation

ABSTRACT In this study, pure polyaniline (PANI0) and polyaniline/titanium dioxide composites, including 15 wt.% TiO2 (PANI15) and 25 wt.% TiO2 (PANI25), respectively, were synthesised using an in-situ polymerisation technique in the absence and in the presence of titanium dioxide nanoparticles, respectively. The solid-phase photocatalytic degradation of polyaniline/titanium dioxide (TiO2) composites was compared with that of the pure polyaniline with the aid of weight loss measurements. The structural and morphological properties of the prepared samples were studied by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis, thermogravimetric analysis and X‐ray diffraction analysis. The loading of TiO2 nanoparticles in polyaniline enhanced the solid-phase photocatalytic degradation of the pure polymer both under UVA light and under UVC light, respectively. Fourier transform infrared spectroscopy illustrated that Pani was synthesised successfully in the presence of TiO2 nanoparticles. Field emission scanning electron microscopy revealed homogeneous TiO2 dispersion within Pani matrix. Thermogravimetric analysis supported the idea that the thermal property of the pure polymer was improved with the photocatalyst contribution. The crystalline structure of TiO2 did not change with Pani.

Sol-gel Preparation of Different Crystalline Phases of TiO<SUB>2</SUB> Nanoparticles for Photocatalytic Degradation of Methylene Blue in Aqueous Solution

This paper describes the photocatalytic degradation of methylene blue (MB) in aqueous solution in the presence of TiO2 nanoparticles (NPs) in different compositions of anatase and rutile phases under UV light irradiation. The different compositions of crystalline phases of TiO2 NPs were synthesized using sol-gel method at the same temperature for various calcination times. The TiO2 NPs were subjected to crystal phase, vibrational, size, and morphological characterizations. The photocatalytic degradation of MB revealed that anatase TiO2 NPs have a superior catalytic activity in the front of rutile phase. This finding further suggested that low charge resistance and low electron-hole recombination probability lead to the acceleration of the OH• formation on the surface of anatase TiO2 NPs.

Surface modification of a cellulose acetate membrane using a nanocomposite suspension based on magnetic particles

Modifying the surface of porous cellulose acetate (CA) flat sheet membranes having 8-hydroxyquinoline (8-HQ, as a complexing agent) was conducted by coating with polyethylene glycol (PEG)/TiO2 nanocomposite solution. Then, nanocomposite solutions were prepared by making magnetite nanoparticles in situ in a polymeric solution prepared by PEG through an easy procedure In addition, the prepared membranes were used for removing Pb(II) ions from aqueous solutions. Further, it was attempted to study the influence of membrane modification, initial feed concentration, and filler loading on the membrane function for discharging above-mentioned ions. The results indicated that the presence of TiO2 nanoparticles and 8-HQ in the membrane structure could enhance the ions rejection. Additionally, several techniques including SEM, FTIR, XRD, porosity, and water contact angle measurements were applied to specify the prepared samples. Morphological studies indicated the appropriate distribution of nanoparticles in the polymeric structure. Finally, it is possible to modify the membrane to create and use them again based on sequential filtration/regeneration experiments.

Supramolecular Self‐Assembly and Organization of Collagen at Solid/Liquid Interface: Effect of Spheroid‐ and Rod‐Shaped TiO2 Nanocrystals

AbstractThe adsorption behavior of collagen on solid surfaces is a process that determines the role of this protein to mediate cell–material interaction. Herein, the mechanism of self‐assembly and organization of collagen on a model substrate is investigated in the presence of TiO2 nanoparticles. In solution, results show that nanoparticles do not alter the conformation of collagen (triple‐helix), and slightly delay the kinetics of its self‐assembly. In the adsorbed state, by exploring the dewetting patterns of collagen layers from atomic force microscopy (AFM) images, a method is developed to extract parameters describing the characteristics of collagen networks. It is shown that collagen layer is strongly impacted by the presence of nanoparticles in the medium. These results are consistent with the analysis of the protein layers in the hydrated state, showing a rigidification, as observed by quartz crystal microbalance with dissipation monitoring (QCM‐D), and the formation of shorter and/or less extended fibrillar structures with a lower surface density, as probed by AFM force spectroscopy. The approach described here provides a reconciliation between disparate views of collagen layers' characterization in the dried and the hydrated states. It also offers new perspectives to assess the impact of nanoparticles on the organization of collagen during in vitro tests, particularly at the stage of cell adhesion.

Self-assembly modification of polyamide membrane by coating titanium dioxide nanoparticles for water treatment applications

This study modified the surface of a commercial polyamide membrane with the deposition of TiO2 nanoparticles by the self-assembly method under pressure with high permeability and photocatalytic activity. Changes in membrane characteristics and its performance for photocatalytic properties were evaluated. The results indicated that both membrane hydrophilicity and photocatalytic performance were significantly improved by the presence of TiO2 nanoparticles applied under a pressure of 1 bar. The deposition of the TiO2 particles under pressure was able to maintain the particles on the surface of the membranes and their photocatalytic capacity for three cycles of use. The prepared TiO2 photocatalytic membrane presented a great potential for wastewater treatment and for reuse wastewater systems due its ability to remove methylene blue (MB) dye solution by photocatalytic decomposition and physical separation.

How titanium dioxide and zinc oxide nanoparticles do affect soil microorganism activity?

The increasing use of nanoparticles (NPs) in recent years has posed a potential threat to the natural ecosystem. The aim of this study was to determine the C and N mineralizations of different textured (clay and sandy) soils at increasing doses of (25, 50 and 100 mg kg−1) TiO2 NPs and ZnO NPs that are biological synthesized from Peganum harmala L. plant extract, and to reveal their potential effects on the soil ecosystem. The carbon (C) and nitrogen (N) mineralizations were respectively determined by the CO2 respiration method and the Parnas-Wagner method under the controlled laboratory conditions for 42 days (28 °C, 80% of field capacity). The highest carbon mineralization among all applications was in clay soils mixed with 100 mg kg−1 TiO2 NPs. In clay soils treated with ZnO NPs, the treatment of 50 mg kg−1 ZnO NPs increased microorganism activity (P < 0.001). Carbon mineralization rates were found to be higher in sandy soils compared to clay soils (P < 0.05). It was observed that these rates were higher in the TiO2 NPs treated soils compared to the ZnO NPs treated soils. The nitrogen mineralization ratios were found to be higher in clay soils compared to sandy soils. All of these results indicate that the microorganisms affected from both the presence of TiO2 NPs and ZnO NPs and differences of texture in these two soils.

Binary-phase TiO2 modified Bi2MoO6 crystal for effective removal of antibiotics under visible light illumination

A series of binary-phase TiO2 modified Bi2MoO6 nanocrystals have been prepared via a solvothermal-calcination process. Trace TiO2 modification can effectively enhance the visible light catalytic activity of Bi2MoO6 to remove the antibiotics in aqueous solution. The obtained TiO2/Bi2MoO6 composites were investigated by some physicochemical techniques like XRD, N2 adsorption, SEM, TEM, UV–vis DRS, Raman, XPS, PL and Photo-electrochemical measurement. The presence of TiO2 nanoparticles (NPs) influenced the crystal growth of Bi2MoO6, decreasing the crystal size of Bi2MoO6 and effectively promoting its specific surface area. Moreover, the conduction band of TiO2 can serve as the electron transfer platform, which largely boosts the effective separation of photocarriers at TiO2/Bi2MoO6 heterojunction interface. With optimal TiO2 content (0.41 wt%), TiO2/Bi2MoO6 exhibited the best photocatalytic performance for different antibiotics degradation, e.g. ciprofloxacin, tetracycline and oxytetracyline hydrochloride under visible light irradiation. Moreover, the mechanism for enhanced photocatalytic performance in ciprofloxacin degradation was illuminated.

Combined effects of surface tension and thermal conductivity on the methane hydrate formation in the presence of both nanoparticles and surfactant

Hydrate has been considered as a promising and cost-effective route for massive storage of natural gas. However, the main problem for this technique to be commercially available is its poor chemical kinetics. In the present study, aiming to reveal the underlying mechanism dominating the hydrate formation kinetics, we investigated combined effects of surface tension and thermal conductivity on the methane hydrate formation. The induction time, gas uptake, and storage capacity for hydrate formation was investigated in detail in the presence of TiO2 nanoparticles and SDS surfactant. The optimal condition for methane hydrate growth was found to be 500 ppm SDS in the presence of 1.0 wt% TiO2 nanoparticles. In this case, the induction time significantly reduced from 183 to 14 min compared to that in pure water. With the addition of SDS alone the surface tension decreased from 72.4 mN/m for pure water to 38.4 mN/m which further decreased to 33.8mN/m, when 1.0% TiO2 was added into the SDS solution. On the other hand, the thermal conductivity of solution showed a continuous increase with the increasing addition of TiO2 while there was an optimal thermal conductivity value for the hydrate growth. It turns out that the optimal addition of TiO2 in SDS solution can result in the lowest surface tension and suitable thermal conductivity, which, in turn, leads to the favorable environment for methane hydrate growth. Our results are supposed to be valuable for the precise control of methane hydrate growth kinetics.

Thermal Stability of Surface Plasmon Resonance Absorption in а-С:Н〈Ag + TiО2〉 Nanocomposite Films

The thermal stability of surface plasmon resonance in a-C:H〈Ag〉 and a-C:H〈Ag + TiО2〉 nanocomposite films is studied. The films were deposited by ion-plasma magnetron sputtering of a combined graphite-metal target in the atmosphere of the argon and methane mixture. The structure and optical properties of nanocomposite films were studied using transmission electron microscopy and optical spectroscopy, respectively. It is found that surface plasmon resonance in the a-C:H〈Ag + TiО2〉 films persists to the annealing temperature of 450°C in argon atmosphere, whereas in a-C:H〈Ag〉 films, surface plasmon resonance disappears at the annealing temperature of 350°C. It is shown that annealing at 350°C leads to the significant increase in the diameter of silver nanoparticles in the structure of the a-C:H〈Ag〉 films. In the a-C:H〈Ag + TiO2〉 films, along with the appearance of silver nanoparticles with a large diameter, silver nanoparticles with a small diameter are present, which remain after annealing at this temperature. The higher thermal stability of surface plasmon resonance in the a-C:H〈Ag + TiО2〉 films is explained by the presence of TiO2 nanoparticles in the structure of films, which inhibit the coalescence of silver nanoparticles at high temperatures.

Heat transfer enhancement in distribution transformers using TiO2 nanoparticles

A transformer is an electrical device that transfers electrical energy between windings by electromagnetic induction while producing a considerable amount of heat in circuits. The heat produced in windings is removed by an appropriate heat transfer fluid such as liquid dielectrics. The cooling and insulating of a liquid dielectric depend on the properties of the oil filling the transformer. One of the approaches to enhance the thermal and dielectric properties of transformer oil is employing an appropriate nanoparticle in a transformer.In this paper, a three-phase distribution transformer is simulated three-dimensionally in order to study the heat transfer efficiency for pure oil (single phase) and nanofluid (TiO2 nanoparticles- transformer oil). For both models, the electromagnetic field in solid sections and heat transfer in fluid and solid sections of the transformer are simultaneously investigated. The simulation results show that the presence of TiO2 nanoparticles in the transformer oil increases the heat transfer coefficient, i.e. adding 1% (vol/vol) of TiO2 nanoparticles to the transformer oil increases the Nusselt number from 2.17 to 2.49, while the maximum temperature of transformer components decreases from 47.20 °C to 43.05 °C.

Synthesis and characterization of polypyrrole – TiO2 coatings on AISI 304 stainless steel

The electrical properties of conducting polymers make them interesting materials to be used in a large number of technological applications. In recent years, an important effect on the anticorrosive properties of the conductive polymer was observed when inorganic particles such as nano-sized TiO2 are incorporated in the conductive matrix. In the present study, polypyrrole films were synthesized in the presence of TiO2 nanoparticles. A study of the electropolymerization conditions, thickness of the formed films and the effect of incorporation of TiO2 nanoparticles on the structure of the polymer matrix by Raman spectroscopy was performed. These results show that it is possible to obtain the adherent coatings, with thicknesses between 3-4 µm. However, the presence of TiO2 nanoparticles in the polymeric matrix influences the corrosion resistance of the polypirrole coatings, destabilizing the natural passive capacity on the surface of AISI 304 stainless steel.

Solid-Phase Photocatalytic Degradation of Polyvinyl Borate

In this study, polymer composites based on polyvinyl borate (PVB) with titanium dioxide (TiO2) nanoparticles were prepared through the condensation reaction of polyvinyl alcohol and boric acid in the presence of TiO2 nanoparticles. The solid-phase photocatalytic degradation of the polymer composites under UV light irradiation was investigated and compared with that of the pure PVB with the aid of weight loss measurements. The introduction of the photocatalyst nanoparticles in PVB enhanced the solid-phase photocatalytic degradation of the polymer matrix under UV light irradiation. The structural and morphological properties of PVB/TiO2 composites were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and UV-Vis spectroscopy, respectively. FTIR analysis revealed that PVB synthesis was successfully carried out in the presence of the photocatalyst nanoparticles. According to the morphological analyses, TiO2 nanoparticles were well dispersed in the PVB matrix.

Diminished inhibitory impact of ZnO nanoparticles on anaerobic fermentation by the presence of TiO2 nanoparticles: Phenomenon and mechanism

Engineered nanoparticle materials (ENMs) are widely and increasingly produced and employed in many sectors. The use of diverse ENMs potentially leads to the release of multiple ENMs into the environment. These ENMs after discharge will be end in wastewater treatment plant and present in sludge. This work investigated the effect of multi-ENMs systems of ZnO and TiO2 on sludge anaerobic fermentation and the related toxicity mechanism. Results revealed that the toxicity of ZnO ENMs on anaerobic fermentation was reduced in the presence of TiO2 ENMs. Investigation on the change of free Zn2+ and reactive oxygen species (OH and H2O2) suggested that both of free Zn2+ and ROS contributed to the toxicity mechanism. Zn2+ decrease was the main reason for the reduced toxicity in multi-ENMs systems. ROS mainly led to the reduction of cell viability in anaerobic fermentation systems. The presence of TiO2 in the multi-ENMs systems promoted the recovery of enzyme activity, cell viability and bacteria abundance.