Titanium Dioxide Dispersions Research Articles

Electroflotation Extraction of Highly Disperse Titanium Dioxide TiO2 from Water Solutions of Electrolytes

The electroflotation extraction of fine particles of TiO2 and Ti(OH)4 was studied. It was determined that in water solutions of electrolytes with pH = 2 – 12 electroflotation of TiO2 proceeds inefficiently: the degree of extraction is 10 – 15%. The degree of extraction is 25 – 30% in the presence of surfactants and 90 – 95% in the presence of surfactants and the coagulant Fe+5. Electroflotation of Ti(OH)4 proceeds efficiently: the degree of extraction at pH = 3 reaches 99%, the electroflotation time 5 – 10 min, and energy consumption 0.5 kW · h/m3 of solution.

Product grinding influence on the drying process of dispersed titanium dioxide paste

Product grinding influence on the drying process of dispersed titanium dioxide paste

Salt enhanced solvent relaxation and particle surface area determination via rapid spin-lattice NMR

This paper demonstrates the influence of surface charge chemistry on the application of nuclear magnetic relaxation measurements (NMR relaxometry) for the in situ determination of particle surface area, in the presence of high electrolyte concentration. Specifically, dispersions of titania, calcite and silica with and without 1 M KCl were investigated. The addition of salt, showed no significant change to relaxation measurements for titanium dioxide; however, a significant rate enhancement was observed for both calcite and silica systems. These differences were attributed to counterion layers forming as a result of the particles surface charge, leading to an increase in the relaxation rate of bound surface layer water. Further, changes appeared to be more pronounced in the silica systems, due to their larger charge. No enhancement was observed for titania, which was assumed to be due to the particles being at their isoelectric point, with no resulting counterion layer formation.Solvent relaxation was further used to successfully determine the surface area of particles in a dispersion using a silica standard reference material, with results compared to Brunauer-Emmett-Teller (BET) and spherical equivalent estimations. Two different dispersions of titanium dioxide, of different crystal phases, were shown to have NMR surface area measurements in good agreement with BET. Thus showing the technique was able to measure changes in surface charge when surface chemistry remained relatively similar, due to the reference silica material also being an oxide. In contrast, the NMR technique appeared to overestimate the calcite surface areas in reference to BET, which was assumed to occur due to both better dispersion in the liquid state of nanocrystallites and potential ion enhancement from the solubility of the calcite. These results highlight the potential of this technique as a fast, non-destructive and non-invasive method for dispersion analysis, but also show the competition between surface area and surface chemistry interactions on measured relaxation rates.

Development Of Flax Fibre Reinforced Epoxy Composite With Nano Tio2 Addition Into Matrix To Enhance Mechanical Properties

Natural fibre reinforced composite has gained a lot of attention in the field of engineering in recent years. Automotive and packing industries are demanding a shift in their design from oil derived polymers and mineral reinforced materials to natural materials focusing in recyclability and bio degradability of green products. Light in weight, low cost of raw materials, easiness in machining are some of the other desirable aspects which thrive them in the market. This work evaluates the ways to improve the mechanical properties of natural fibre reinforced composites to compete with the synthetic fibre composites. The objective of this research is to investigate the effect of dispersing Titanium dioxide (TiO2) nanoparticle with size 15nm in Flax fibre reinforced epoxy composite. Matrix modification is done by mixing Nano TiO2 in epoxy resin which in turn increases the mechanical properties of the final composite by improving the fibre matrix bonding. Flax fibre woven mat is selected as reinforcement. Matrix selected is Epofine 556 with Finehard 1972 hardener. Hand layup technique is selected as the fabrication process and the mechanical properties in terms of tensile strength are assessed. Outcome of fibre volume fraction and influence of alkali treatment with 5% and 10% NaOH solution are also explored and the results of mechanical testing are presented in this paper.

The Dispersion Process based on Organic-inorganic Composite Technology and its Application in Thermal Reflective Insulation Coatings

With the photochemical activity of titanium dioxide, the surface polymer encapsulation is conducted to titanium dioxide under ultraviolet light initiation. It studies the influence of light source type, light exposure time and rate of charge on the product structure; the dispersion oftitanium dioxide was compared before and after modification by using light absorption method; the modified titanium dioxide was prepared into thermal reflective insulation coating, and the difference of thermal barrier effect among uncoated, rock wool board and thermal reflective insulation coating was contrasted by self-made equipment.

Development of tensile-compressive asymmetry free magnesium based composite using TiO2nanoparticles dispersion

Abstract

Fe-Doped TiO2 Supported on HY Zeolite for Solar Photocatalytic Treatment of Dye Pollutants

Zeolite-supported TiO2 and Fe-doped TiO2/zeolite photocatalysts were synthesized, aiming at improving the adsorption properties of the microporous support towards polluting dyes and the photocatalytic performance of TiO2 in the treatment of the adsorbed organics. The TiO2/HY zeolite catalyst exhibited the best performance in the photocatalytic degradation of methylene blue, MB, over 10 wt% TiO2/HY under UV light at 254 nm. The addition of Fe species in the synthesis mixture led to Fe-TiO2/HY catalyst. The combination of adequate zeolite, good titanium dioxide dispersion, and Fe doping led to a remarkable performance in the degradation of the model dye. Over a 10 wt% Fe-doped TiO2/HY catalyst a total removal of MB (>98%) was achieved after 60 min under very mild conditions and simple visible light irradiation.

Synthesis and characterization of green membranes polyimide/titania bionanocomposites containing amino acid and benzimidazole moieties for gas transport properties

In the presented study, the synthesis and full characterization of four different new diamine and polyimides derived from amino acids, including isoleucine (Ile), valine (Val), methionine (Met), phenylalanine (Phe) and benzimidazole fractions in the structure of pendant group is presented. The polymerization reactions of these monomers provided a series of new optically active polyimides (PIs) with inherent viscosities in the range of 0.68–0.98 dL g−1. The obtained polymers were characterized by Fourier‐transform infrared spectroscopy, specific rotation measurements, and the representative of them by proton nuclear magnetic resonance, gel permeation chromatography and elemental analysis techniques. The new diamine monomer containing L‐isoleucine is employed as a key monomer for the sol–gel fabrication of a series of PI/titania nanohybrid films with various titania percentages. The special design of diamine monomer containing bulky pendant group increased the flexibility of resulted PIs. On the other hand, the ability to construct strong organic/inorganic H‐bond lattice has led to the effective surrounding of titania by PI grounds and thus the well‐dispersed quite spherical NPs were created via a sol–gel procedure. The dispersion of titania in PI films was confirmed by the transmission electron microscope (TEM) analysis showing the well‐dispersed nanosized titania NPs. The thermogravimetric analysis data showed an improvement of thermal stability of novel bionanocomposite films as compared to the pure PI. Gas permeation measurement showed that PI embedded with different amount of titania exhibited different separation performances. POLYM. ENG. SCI., 58:1666–1677, 2018. © 2017 Society of Plastics Engineers

Relationship between Ionic Interation and NMR Relaxation Behavior in LiClO4-PC Solution Coexisting with Fumed Metal Oxide

Lithium ion battery (LIBs) is indispensable to various electrochemical devices in practical use such as a cell phone, electric vehicle due to its high energy density, high voltage. Although the extended use of LIBs technology, batteries which have higher capacity and can stand up to high speed charge/discharge than those of LIBs are demanded. Various studies have reported that the liquid phase occurring adjacent to solid particles has an anomalous behavior when compared to bulk solution[1]. Solid-liquid interface is performed as a base in charge-discharge of LIBs, so an elucidation of liquid phase properties of solid-liquid interface in the non-aqueous electrolyte solution system is important for improving the performance of energy storage devices such as LIBs. In addition, properties of the highly-concentrated electrolytes for performance improvement of LIBs are attracted. In this study, NMR spectroscopic behavior of non-aqueous LiClO4 solution mixed with fumed oxide nanoparticles as model system of gel electrolyte for LIBs, and their dynamic properties and influences to solvent molecules from solid phase or Li+ ion by measurement of the spin-spin (T 2) relaxation time and electrochemical measurement. Samples were prepared in Ar glovebox by mixing propylene carbonate(PC) or LiClO4/PC of predetermined concentration (1-3 mol L-1) and fumed silica(FS) (200 ± 20 m2 g-1), amorphous silica nanoparticles with self-cohesive properties, fumed alumina(FA) (130 ± 20 m2 g-1) and fumed titania(FT) (90 ± 20 m2 g-1) in NMR tube. A content of liquid phase were ranged from 90-100 vol% by gravimetry. We measured 1H and 7Li NMR spectroscopy (Varian INOVA 400; 9.39 T) and 1H spin–spin relaxation time; T 2measurements (XiGo Nanotools Acorn area ; 0.3 T). In 1H NMR spectra, a broad signal was confirmed under the existence solid-phase. It was shown that the dynamic property of PC molecules largely decreased in comparison with the case only for liquid phases. In PC/FS and PC/FA system, 1H NMR spectra shifted to higher magnetic field with the decrease of liquid content. For the shielding effect to the 1H nucleus of the PC molecules by the surface charge of fumed silica, a signal continues to shift to highly-magnetic field as a content of solid-phase increases. This result suggested that the apparent charge densities around the proton of PC molecules increased by fumed silica because fumed silica has a negative charge. In alumina dispersion, NMR signal shifted to higher magnetic field than that of fumed silica. From this result, alumina gives more influence on dynamics properties of liquid phase. A similar result was observed in 1-3 mol L-1 LiClO4/PC and solid coexisting system. From the liquid content dependences of the 1H NMR detection ratios of propylene carbonate, almost same amount of PC molecules were detected in PC/FS coexisting system. This result indicated that fumed silica formed network structure but H of PC molecules remained its dynamics. On the other hand, in fumed alumina or fumed titania dispersion, values of PC molecules detected by NMR decreased compared to the theoretical value of detected amount of PC by 1H NMR. It suggests that the mobility of PC molecules in fumed alumina and titania system were restricted than that in silica system. T2 in solid-liquid coexisting system is also shown in Fig. 1. From Fig.1, in all systems, the T2 value decreases because the dynamics of water molecules of the liquid phase decrease. The T2 value decreased in order of PC/FA, PC/FT, PC/FS system. The influence of the solid surface to solvent mobility in fumed alumina dispersion is the least of the three. This result supports a signal of the NMR and the result of 1H qNMR measurement. We will also discuss the NMR relaxation behavior for LiClO4-PC solution coexisting with te same fumed metal oxides. This study was supported by the JST Core Research for Evolutional Science and Technology (CREST). 【Reference】 [1] M. Mizuhata et al., J. Mol. Liq., 83, 179, (1999). Figure 1

Facile fabrication of epoxy-TiO2 nanocomposites: A critical analysis of TiO2 impact on mechanical properties and toughening mechanisms

Optimized ultrasonic assisted dispersion of un-functionalized titanium dioxide (TiO2) nanoparticles (0.5–20wt%) into epoxy resin is reported. The investigation shows that there is a direct relation among nanoparticles content, inter-particle spacing and cluster size of the particles on the glass transition temperature (Tg) and tensile properties of the prepared nanocomposites. A significant improvement in tensile strength and modulus with minimal detrimental effect on the toughness was observed for the prepared composites, where compared to pristine epoxy resins, about 26% and 18% improvement in tensile strength and strain-to-break %, respectively, was observed for 10wt% particles loading, whereas a maximum improvement of about 54% for tensile toughness was observed for 5wt% particles loaded resins. The investigations found that a strong particle–matrix interface results in the enhancement of the mechanical properties due to leading toughening mechanisms such as crack deflection, particle pull out and plastic deformation.

Experimental study on solidification process of a phase change material containing TiO2 nanoparticles for thermal energy storage

The solidification process of n-octadecane as a phase change material (PCM) with dispersed titanium dioxide (TiO2) nanoparticles was experimentally studied. Experiments were performed in a rectangular enclosure cooled from one vertical side corresponding to the solid Stefan numbers in the range 0.17–0.239. The Rayleigh numbers at the initial of experiment were in the range 0.92–18.3×106. The rheological behavior of liquid PCM/TiO2 samples at higher concentrations tended to Bingham fluids, thus the solidification experiments were conducted for Bingham numbers in the range 0–2.17. The solidification process was characterized by visualizing the progression of solid-liquid interface as well as recording the temperature distribution inside the enclosure. Experimental results showed that heat conduction was the dominant mode of heat transfer during the solidification. Dispersing TiO2 nanoparticles led to enhance in thermal conductance and consequently the increase in solidified volume. An increase of 7%, 9% and 18% in solidified volume fraction was observed at the end of solidification for the mass fractions of 1wt.%, 2wt.% and 4wt.%, respectively. A universal correlation was proposed to predict the solidified volume fraction as a function of Fourier number, Rayleigh number, solid Stefan number, Bingham number and mass fraction of nanoparticles with an error below 11%.

Tribological Performance of TiO2-Nanostructured Particles as Oil-Lubricant Additives for Different Iron-Carbon Alloys

We evaluated the tribological performance of a dispersion of titanium dioxide (TiO2) nanostructured particles in car engine base oil for three different iron-carbon alloy materials (bearing steel, carbon steel and cast iron) in a disc–disc tribometer. The lubrication, friction and wear performance of the nanostructured particles was measured by testing three different configurations: 1) pure base oil, 2) base oil with additive package and 3) nanodispersion formulation. For the bearing steel – carbon steel configuration we found that the oil additive package reduces the coefficient of friction from µ =0.12 to µ=0.03. Upon adding TiO2-nanostructured particles to this formulation a further friction reduction by a factor of 3 to a superior frictional coefficient of µ<0.01 could be measured. This effect, however, could not be verified for the other two alloy material combinations, where the frictional coefficient was not affected by the nanostructured particle addition. Since carbon steel is characterized by the lowest Brinell hardness of the three tested alloy materials and exhibited the lowest surface roughness after the test procedure, we attribute the observed friction reduction to a lubricating titanium (dioxide) overlayer that builds up on the carbon steel surface but not on bearing steel and cast iron. This is supported by element-specific energy dispersive X-Ray analysis (EDX). Further attempts to optimize and predict nanotribological formulations for industrial applications are under way.

A comparative study of the incorporation of TiO2 into MCM-41 nanostructure via different approaches and its effect on the photocatalytic degradation of methylene blue and CO oxidation

Two sets of titania incorporated within mesoporous MCM-41 were successfully fabricated through two fundamental approaches to look for better dispersion of titania and robust catalysts for the photocatalytic degradation of methylene blue and carbon monoxide oxidation. The first involves the incorporation of titania via a one-pot synthesis method to produce Ti-MCM-41. The second approach carried out uses the post-impregnation method to deliver TiO2/MCM-41 with various titania contents. The synthesized materials were characterized by inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV–Vis diffuse reflectance spectroscopy, nitrogen physisorption, high resolution transmission electron microscopy (HRTEM) and field emission scanning electron microscopy (FESEM). The results demonstrate that, as compared with the post-impregnation approach, the one-pot synthesis of titanium into MCM-41 assists the incorporation and the good dispersion of titanium ions into the mesochannel of MCM-41 frameworks. It also hinders the growth of large TiO2 crystallites, which are beneficial to produce outstanding catalysts for the photocatalytic degradation of methylene blue and carbon monoxide oxidation. It is conceivable to propose that the strategy of preparation did pronouncedly contribute to the overall activity.

Development of highly reinforced acrylonitrile butadiene rubber composites via controlled loading of sol-gel titania

Remarkable improvement in mechanical properties of acrylonitrile butadiene rubber (NBR) composites is achieved by incorporating nano-titania that is synthesised in solution of the raw rubber using titanium n-butoxide (TNB) as the titania precursor. This is achieved by designed and controlled incorporation of titania that resulted in very good dispersion of titania of nanometric dimension in rubber matrix and enhanced rubber-filler interaction. This sol-gel transformation is carried out under optimised reaction condition. Surface modification of titania by a silane coupling agent (bis-(3-triethoxysilylpropyl)-tetrasulfide, TESPT) causes further improvement in filler dispersion and composite properties when added in the reactive sol-gel system during in situ titania generation rather than it's external addition in the titania filled NBR during mixing and compounding. Thorough characterisation of the composites are done that encompasses a wide range of studies on thermal, morphological, mechanical, dielectric, dynamic mechanical, rheological and antifungal properties. The results are analysed on a comparative basis to investigate the effect of in situ incorporation and in situ surface modification of titania on the composite properties.

Balance of mechanical and electrical performance in polyimide/nano titanium dioxide prepared by an in‐sol method

ABSTRACTHybrid polyimide (PI)/titanium dioxide (TiO2) films were prepared by in situ polymerization and sol–gel and in‐sol methods (where in‐sol method indicates that in situ polymerization and the sol–gel method were used in the same samples). The mechanical and electrical properties were found to be sensitive to the processing methods and the dispersion of nano titanium dioxide (nano‐TiO2) in the PI matrix. For the PI/TiO2 films prepared by the in situ polymerization method, their tensile strength increased with increasing TiO2‐in situ (“TiO2‐in situ” is “the TiO2 nano‐particles prepared by in situ polymerization method”) concentration. However, the optimal corona lifetime of the PI/TiO2 films was 15 min at 20 kHz and 2 kV because of poor dispersion. For the PI/TiO2 films prepared by the sol–gel method, the corona lifetime reached 113 min because of superior dispersion and a tensile strength of about 19.63 MPa. A balance of mechanical and electrical performances was achieved with the in‐sol method. The corona‐resistant life of the PI/TiO2 films was 43 min, which was about six times longer than that of the neat PI. Their tensile strength was 83.5 MPa; these films showed no decrease in this value compared with the pure PI films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44666.

Dispersion of Titanium Oxide Nanoparticles in Aqueous Solution with Anionic Stabilizer via Ultrasonic Wave

This paper aims to reveal the effects of odium hexametaphosphate (SHMP) and polyacrylic acid (PAA) on dispersion of TiO2 (P25) nanopowder in de-ionic water through ultrasonic horn. We characterized TiO2 suspension by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), zeta potential, and surface contact angle instruments. As shown in the results, particularly, it were noticed that (1) the SHMP has better dispersion than PAA due to electronegativity effect, resulting in that the average particle size of the dispersed titanium dioxide in de-ionic water was roughly 92 nm, and (2) the zeta potential of TiO2 suspension with SHMP can be achieved by 54 mV at pH value of 7.7, causing stronger electrostatic repulsion in the suspension solution, compared with PAA.

All-printed planar photoelectrochemical cells with digitated cathodes for the oxidation of diluted aqueous pollutants.

A novel outline of a planar photoelectrochemical cell consisting of a semiconductor layer topped by subsequent layers of a digitated insulator and counter electrode is introduced. The use of vertically separated electrodes represents a major development in reducing the footprint (inactive areas) of planar electrochemical cells. The cells, consisting of a nanoparticular titania photoanode and a digitated, metallic cathode, were fabricated by a strictly additive process employing material printing as the exclusive deposition and patterning tool. Transparent conductive oxide-coated glass and polyethyleneterepthalate sheets were used as substrates; nanocrystalline titania dispersion bonded by a novel organosilica binder was used for the fabrication of the photoanode and gold or carbon inks for the fabrication of the digitated cathodes. Due to the digitated shaping of the cathode, photoelectrochemical response was not suffering from iR drop down to low electrolyte ionic strengths. The printed cells were used for electroassisted photocatalytic degradation experiments with aqueous solutions of coumarin. Considerable acceleration of the coumarin degradation rate compared to the plain photocatalytic mode was observed.

TiO₂-Based Photocatalytic Geopolymers for Nitric Oxide Degradation.

This study presents an experimental overview for the development of photocatalytic materials based on geopolymer binders as catalyst support matrices. Particularly, geopolymer matrices obtained from different solid precursors (fly ash and metakaolin), composite systems (siloxane-hybrid, foamed hybrid), and curing temperatures (room temperature and 60 °C) were investigated for the same photocatalyst content (i.e., 3% TiO2 by weight of paste). The geopolymer matrices were previously designed for different applications, ranging from insulating (foam) to structural materials. The photocatalytic activity was evaluated as NO degradation in air, and the results were compared with an ordinary Portland cement reference. The studied matrices demonstrated highly variable photocatalytic performance depending on both matrix constituents and the curing temperature, with promising activity revealed by the geopolymers based on fly ash and metakaolin. Furthermore, microstructural features and titania dispersion in the matrices were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analyses. Particularly, EDS analyses of sample sections indicated segregation effects of titania in the surface layer, with consequent enhancement or depletion of the catalyst concentration in the active sample region, suggesting non-negligible transport phenomena during the curing process. The described results demonstrated that geopolymer binders can be interesting catalyst support matrices for the development of photocatalytic materials and indicated a large potential for the exploitation of their peculiar features.

Adsorption studies for the acrylic polyester hyper-dispersant on titanium dioxide

ABSTRACTA novel acrylic polyester hyper-dispersant was used to disperse titanium dioxide in different organic solvents. The adsorption behaviors were investigated in ethyl acetate, toluene, and isopropyl alcohol. Meanwhile, the data of adsorption isotherms were correlated using the Langmuir, Freundlich, Redlich–Peterson, Tempkin, and Fritz–Schlunder models. The results showed that the four-parameter Fritz–Schlunder isotherm equation was the best correlation. The mean free energy of sorption was calculated by Dubinin–Radushkevick equation using the adsorption data and its E value was 2.09–3.11 kJ mol−1, this indicated the adsorption was a physical process in accordance with the FTIR test result.

Synthesis and properties of novel acrylic polyester hyper-dispersant

3-Pentadecylphenyl acrylate (PDPA) was synthesized from renewable sources (the cashew nut shell liquid), by using a novel organic chemical intermediate that can be used to copolymerize with vinyl monomers. A novel acrylic polyester hyper-dispersant was prepared by polymerization of methacrylic acid (MAA), butyl acrylate (BA), and PDPA. The acrylic polyester hyper-dispersants were used to disperse titanium dioxide in non-polar solvent system, and the dispersion performance was studied. The viscosity and particle size of suspensions were affected by monomer ratio and molecular weight; the results showed that the optimum monomer ratio and molecular weight were MAA:BA:PDPA = 1:10:1.2 (wt%) and 6000, respectively. The optimum amount weight of MAA of acrylic polyester should be around 10% (wt%).