Titanium Dioxide Dispersions Research Articles

Optimization of a Droplet-Based Millifluidic Device to Investigate the Phase Behavior of Biopolymers, Including Viscous Conditions

Phase diagrams are widely used to map and control the assembly states of biopolymers. However, these studies are highly time and material consuming. Here, we present the optimization of a simple tool based on millifluidics to screen phase diagram of biopolymers, pure or in mixtures with other biopolymers. It is used (i) to generate a homogeneous mixture of biopolymers/buffer and/or biopolymers 1/ biopolymers 2 in a short time (~s), (ii) to vary the composition of the mixtures by adjusting the flow rates, and (iii) to determine the turbidity of the drop by grey level analysis. The mixing efficiency and the calibration turbidity vs. grey level were performed using colloidal titanium dioxide dispersions. The use of millifluidics reduced the amount of material of ten-fold and the experimentation time by a factor five compared to a conventional bulk approach. This set-up was used to explore functional synergies between proteins and polysaccharides as an example of application.

The effect of thermal and non-thermal routes on treatment of the Mg–Al layered double hydroxide catalyst dispersed by titania nanoparticles in products distribution arising from poly(ethylene terephthalate) degradation

The development of sustainable catalysts in the chemical recycling of polyethylene terephthalate (PET) can help to improve the circular economy of this material. In this study, the degradation of PET to the bis(2-hydroxyethyl) terephthalate (BHET) monomer and other main products was investigated by Mg–Al layered double hydroxides (LDHs) dispersed by 20 wt% of titania nanoparticles (NPs). The PET conversion and BHET yield of LDHs treated by thermal and non-thermal treatment routes were compared to assess the thermostability and catalytic activity of LDHs. The LDHs loaded by titania NPs showed higher thermal stability than the unloaded LDHs. A synergistic effect between the brucite sheets and titania was found by using a combination of freeze-drying (FD) and dielectric barrier discharge (DBD) plasma routes, associated with the high dispersion of titania with size ranges of 5–10 nm. The PET conversion and the BHET yield of LDH-FD-DBD were higher than the catalysts annealed by calcination. The high stability of the LDH-FD-DBD allowed it to be reused five times without notable catalytic activity reduction. The proposed technique was an effective approach to manipulate the properties of LDH dispersed by titania NPs that enabled the catalyst to display high activity towards PET degradation.

Dispersion stability of titanium dioxide in aqueous isopropanol with polymer dispersant

Two polymer dispersants, polyester dispersant (PD) and sodium polyacrylate (NaPAA), were used to disperse titanium dioxide in 10% aqueous isopropyl alcohol (IPA). The effect of pH and zeta potential on the dispersibility of the titanium dioxide (TiO2) was studied via sedimentation. An optimum pH value of 8 for the two polymer dispersants in aqueous IPA suspension was found. The isoelectric point of the TiO2 particles was at pH 5.1 and pH 5.3 and shifted to lower pH in the presence of PD or NaPAA, with a greater decrease in zeta potential for the NaPAA suspension (− 36.5 to − 64.1 mV) due to the high degree of ionization compared with PD (− 36.5 to − 60.6 mV). The conformations of PD and NaPAA were strongly pH dependent: Their adsorption was highest at low pH and lowest at high pH, with the maximum adsorption of PD and NaPAA being 44.0 and 39.2 mg g−1 at pH 3, respectively. It was shown that the stability of the suspensions was not only dependent on the pH but also on the zeta potential and molecular structure of the dispersant.

Efficient Chemical Mechanical Polishing of AISI 52100 Bearing Steel with TiSol-NH4 Dispersion-Based Slurries

In this paper, chemical mechanical polishing technique was used to prepare an ultra-smooth surface of AISI 52100 steel. It was found that an unexpectedly high MRR of 500 nm/min and a satisfactory surface roughness Ra of 4.0 nm are achieved simultaneously by the synergistic effect of TiSol-NH4 dispersion and H2O2 at near neutral pH 6.0. During the polishing process, the organic base in TiSol-NH4 dispersion and H2O2 can be smoothly transported to the contact area along with uniformly dispersed titanium dioxide as nanocapsules, and then the chemicals for oxidation and complexation are provided to form a reaction film on the AISI 52100 steel surface, while abrasive nanoparticles provide sufficient mechanical force to abrade such a reaction film successively. With the addition of a small amount of H2O2, a porous composite layer composed of iron oxides and iron complex compounds with relatively low mechanical strength can be rapidly formed on the top surface. Therefore, the MRR first dramatically increases. When the H2O2 concentration crosses 0.1 wt% at the MRR summit and further increases, the layer gradually grows compact with high mechanical strength. Therefore, the MRR then gradually decreases. The findings can provide an efficient approach for processing bearing steels with excellent surface integrity.

Nanocomposite Titania-Carbon Spheres as CO2 and CH4 Sorbents.

Photocatalysis can offer solutions for the transformation of greenhouse gases, such as methane and carbon dioxide. In the paper, a candidate for such a photocatalyst is presented, based on a composite of titania with carbon spheres. The material was obtained using microwave assisted solvothermal synthesis, enabling good dispersion of titania. The studies of carbon dioxide and methane adsorption were performed under ambient pressure and temperatures of 40, 60, and 80 °C. The effect of temperature increase was less favorable for carbon dioxide than for methane. Satisfying values of carbon dioxide and methane uptake were obtained—3.94 mmol CO2/g and 2.77 mmol CH4/g at 40 °C.

Sodium ion conducting nanocomposite polymer electrolyte membrane for sodium ion batteries

The paper reports effect of dispersion of titanium dioxide (TiO2) nanofiller on the sodium ion conducting nanocomposite polymer electrolyte membranes consisting of TiO2 dispersed membranes of poly(vinylidenedifluoride-co-hexafluoropropylene) (PVdF-HFP) soaked in a liquid electrolyte of sodium hexafluorophosphate (NaPF6) in ethylene carbonate (EC) and propylene carbonate (PC). The TiO2 dispersed membranes have been prepared by phase inversion technique. The structural and morphological properties of the polymer electrolyte membranes have been investigated using x-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The membranes have been found to be highly porous with maximum porosity ~ 72% and liquid electrolyte uptake ~ 270%. Ionic conductivity of the electrolyte membranes containing different concentrations of TiO2 has been measured by complex impedance spectroscopy. The maximum room temperature ionic conductivity has been found to be ~ 1.3 × 10−3 S cm−1. The ionic conductivity measured with temperature has been found to follow VTF behavior. The ion transport numbers of the membranes have been studied using dc polarization, complex impedance, and cyclic voltammetry. The membranes have been found to be predominantly ionically conducting with Na+ transport number ~ 0.31. The electrochemical stability window of the membranes has also been measured using cyclic voltammetry and found to be 3.5 V.

Development of the Technology to Obtain Finely Dispersed Titanium Dioxide from the Solutions of Titanium Salts

Development of the Technology to Obtain Finely Dispersed Titanium Dioxide from the Solutions of Titanium Salts

О ВОЗМОЖНОСТИ ПОЛУЧЕНИЯ ПОРОШКА ДИОКСИДА ТИТАНА, СИНТЕЗИРОВАННОГО ПЛАЗМОДИНАМИЧЕСКИМ МЕТОДОМ

These days, environmental pollution problems are relevant, therefore, the problems associated with photocatalysis as a direction for the future development of alternative energy are solved by many world scientists. Titanium dioxide TiO2 is known to be a photocatalytic material with many unique properties. However, its use is limited due to its wide band gap and the high recombination rate of electron pairs. The method of direct plasma dynamic synthesis of dispersed titanium dioxide was proposed. It was established that the synthesized product consisted of two fractions which had different sizes: a coarse fraction with particle sizes from ~10 microns to ~100 microns and a fine one - from ~10 nm to ~1 micron. It was also revealed that fractions mainly consisted of two TiO2 crystalline modifications: anatase and rutile with tetragonal syngony.

Development of the Technology to Obtain Finely Dispersed Titanium Dioxide from the Solutions of Titanium Salts

Development of the Technology to Obtain Finely Dispersed Titanium Dioxide from the Solutions of Titanium Salts

Effect of molecular weight of polcarboxylate surfactant on properties of concentrated aqueous titanium dioxide dispersions

Universal colorants used for point-of-sale tinting or dealer tinting system usually have titanium dioxide dispersion as one of the essential colorants to adjust “chroma” of the shade. It is imperative that this colorant exhibits optimum performance in water-based and solvent-based products. The paper focuses on the effect of varying molecular weight of polycarboxylate-based surfactants on the properties of the aqueous dispersion.

Titania-loaded cellulose-based functional hybrid nanomaterial for photocatalytic degradation of toxic aromatic dye in water

The dispersion of Titania on cellulose nanowhiskers was achieved using titanium tetra-isopropoxide as the precursor and sulphuric acid as a peptizing agent via the low-temperature sol-gel synthesis method. The photocatalytic activity of the resultant hybrid catalyst was studied through photocatalytic removal of toxic aromatic cationic thiazine dye (methylene blue). Diverse instrumental methods used for full characterizations of pristine and prepared materials allowed correlating the type of the chemical moiety incorporated to the formation of Titania-loaded cellulose-based functional nanomaterial as well as its stability and catalytic performance. Results indicated successful synthesis of multiscale Titania (19 nm ∼1 μm) and perpetual distribution over cellulose nanowhiskers. The latter showed high photocatalytic behavior towards the degradation of methylene blue (conc. 50 ppm) dye. The degradation reached 98.5 % in 40 min at a reaction rate of 0.188 min-1 as observed and measured through UV–vis spectrophotometer. Chemical oxygen demand (COD) analysis reveals substantial mineralization of the pollutants by reducing toxicity up to 68.64 % with complete recovery of the catalyst validated by total dissolved solids (TDS) analysis of treated water. Considering the above results, a mechanism has postulated. Kinetic study showed that the degradation reaction obeys pseudo-first-order reaction kinetics with appreciable recyclability after five (05) repeated uses. The results herein open new prospects for cellulose-based functional nanomaterial for various environmental applications.

Fabrication of High Permittivity Resin Composite for Vat Photopolymerization 3D Printing: Morphology, Thermal, Dynamic Mechanical and Dielectric Properties.

The formulation of a high dielectric permittivity ceramic/polymer composite feedstock for daylight vat photopolymerization 3D printing (3DP) is demonstrated, targeting 3DP of devices for microwave and THz applications. The precursor is composed of a commercial visible light photo-reactive polymer (VIS-curable photopolymer) and dispersed titanium dioxide (TiO2, TO) ceramic nano-powder or calcium copper titanate (CCT) micro-powder. To provide consistent 3DP processing from the formulated feedstocks, the carefully chosen dispersant performed the double function of adjusting the overall viscosity of the photopolymer and provided good matrix-to-filler bonding. Depending on the ceramic powder content, the optimal viscosities for reproducible 3DP with resolution better than 100 µm were η(TO) = 1.20 ± 0.02 Pa.s and η(CCT) = 0.72 ± 0.05 Pa.s for 20% w/v TO/resin and 20% w/v CCT/resin composites at 0.1 s−1 respectively, thus showing a significant dependence of the “printability” on the dispersed particle sizes. The complex dielectric properties of the as-3D printed samples from pure commercial photopolymer and the bespoke ceramic/photopolymer mixes are investigated at 2.5 GHz, 5 GHz, and in the 12–18 GHz frequency range. The results show that the addition of 20% w/v of TO and CCT ceramic powder to the initial photopolymer increased the real part of the permittivity of the 3DP composites from ε’ = 2.7 ± 0.02 to ε’(TO) = 3.88 ± 0.02 and ε’(CCT) = 3.5 ± 0.02 respectively. The present work can be used as a guideline for high-resolution 3DP of structures possessing high-ε.

TiO2‐PDVB Janus particles enhanced compatibility of titanium dioxide and recycled waste styrofoam

ABSTRACTPeople are always puzzled by “white pollution” in recent decade. Recycling of waste styrofoam as a coating is a good sustainable solution to resolve this problem. However, the poor compatibility between inorganic additives and polymer hinders the application of recycled polystyrene. In this article, anisotropic Janus particles were used to increase the compatibility of titanium dioxide/waste styrofoam coatings. SEM results show that Janus particles can be anchored at the interface between styrofoam and titanium dioxide, increasing the dispersion of titanium dioxide, and improving the compatibility of inorganic particles and organic polymer. The glass‐transition temperature of styrofoam coating increases from 77 °C to 89 °C in titanium dioxide/styrofoam contained 1 wt % of Janus particles, which certified that Janus particles have compatibilization on titanium dioxide/styrofoam coating. Attributing to this compatibilization, the tensile strength of titanium dioxide/styrofoam with 1 wt % of Janus particles rises about 45% compared with titanium dioxide/styrofoam. The yield stress, storage modulus, and viscosity of titanium dioxide/styrofoam contained 1 wt % of Janus particles are the smallest and the closest to Newtonian fluid. Janus particles used in the recycled styrofoam coating is benefit to expand the application of waste styrofoam and the new anisotropic Janus compatibilizer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48691.

ИССЛЕДОВАНИЕ ДИСПЕРГИРУЮЩЕГО ЭФФЕКТА ПОЛИМЕРНЫХ ПОВЕРХНОСТНО-АКТИВНЫХ ВЕЩЕСТВ В АКРИЛОВЫХ ДИСПЕРСИЯХ, ПРИМЕНЯЕМЫХ ДЛЯ ОКРАСКИ УСТЬЕВОЙ АРМАТУРЫ НЕФТЯНЫХ СКВАЖИН

Актуальность работы обусловлена необходимостью создания новых воднодисперсных лакокрасочных материалов с повышенным эксплуатационным ресурсом, согласно жёстким требованиям ПАО «НК «Роснефть» для защиты от атмосферной коррозии устьевой арматуры нефтяных скважин. В связи с ужесточением экологических требований во многих странах мира возросло использование воднодисперсных лакокрасочных материалов. Так, один из крупнейших производителей устьевой арматуры нефтяных скважин в Республике Казахстан – АО «Казнефтегазмаш» – принципиально использует для окраски своих изделий только воднодисперсные акриловые лакокрасочные материалы: грунтовку «Уникор-М» ТУ 2316-002-0-31953544-96 и краску «Акрэм-Металл» ТУ 2316-003-0-31953544-96. Однако основные российские нефте- и газодобывающие компании, в частности ПАО «НК «Роснефть», ПАО «Газпром» и др., в последнее время резко ужесточили требования к сроку защитного ресурса лакокрасочных покрытий. Так, согласно технологической инструкции ПАО «НК «Роснефть» № П2-05 ТИ-0002 «Антикоррозионная защита металлических конструкций на объектах нефтегазодобычи, нефтегазопереработки и нефтепродуктообеспечения компании», минимальный защитный ресурс лакокрасочных покрытий в зависимости от условий эксплуатации, составляет не менее 10 лет. А применяемые АО «Казнефтегазмаш» акриловые лакокрасочные материалы обеспечивают защитный ресурс покрытий не более 5 лет. Поэтому с учетом всего вышеперечисленного нами предпринята попытка увеличения защитного ресурса лакокрасочного покрытия путем получения более однородного распределения пигмента в полимерной матрице, за счет применения поверхностно-активных веществ. Целью работы являлось изучение влияния полимерных поверхностно-активных веществ на диспергирование пигмента (диоксида титана) в водной дисперсии акрилового полимера. Методы: компьютерно-оптическая микроскопия и математическое моделирование. Результаты и выводы. Представлены результаты исследования влияния полимерных поверхностно-активных веществ марки TEGO: Glide 100 (полиэфирсилоксановый сополимер) и Dispers715w (полиакрилат натрия), на диспергирование диоксида титана (марка R-02) в водной акриловой композиции. Показано, что Glide 100 и Dispers 715w при содержании в композиции от 0,25 до 0,5 г/дм3 улучшают диспергирование пигмента. Наиболее эффективной добавкой является Dispers 715w, при этом диаметр частиц пигмента уменьшается в два раза (с 8 до 4 мкм). Выведены уравнения, описывающие влияние содержания и вида поверхностно-активных веществ на диаметр частиц пигмента, и на их основе построены номограммы. Разработанные лакокрасочные материалы могут использоваться для окраски устьевой арматуры нефтяных скважин.

Performance of Composite Membrane for Palm Oil Wastewater Treatment

Polyvinylidene fluoride (PVDF) composite membranes were prepared via phase inversion method by dispersing titanium dioxide (TiO2) in the dope solution. It is aimed to study the effects of TiO2 on the membrane surface properties and thus its separation performance. The PVDF membranes modified by various TiO2 contents were characterized with respect to cross-sectional structure, average pore size, effective porosity, hydrophilicity, permeability and rejection. Maximum values of membrane hydrophilicity, membrane porosity and average pore size were achieved upon addition of 1.95% TiO2. It is found that changes in the membrane surface properties are closely corresponded with the membrane fouling. The maximum flux and rejection of organic pollutants from palm oil wastewater were recorded at 82.5 L/m2 h and 98.8 %, respectively using PVDF composite membrane incorporated with 1.95% TiO2.

Modification of physical and thermal characteristics of stearic acid as a phase change materials using TiO2-nanoparticles

The present study aimed to introduce a novel method to prepare nanoparticles enhanced phase change materials (NePCMs) with high stability and thermal conductivity. First, the NePCMs were prepared by dispersing titanium dioxide nanoparticles (TiO2-NPs) in stearic acid (SA) with 0.09, 0.26, 0.33, and 0.36 wt% using sedimentation balance method (SBM). Then, the structural, thermal and chemical properties of samples were evaluated. The results of structural analysis indicated that nanoparticles were dispersed uniformly in SA. In the next process, the most likely unstable sample was applied in frequently thermal melting and solidification cycles test. Based on the results, the chemical stability and thermal reliability of NePCMs remained excellent after 250 cycles, which make it proper to be applied in long-term consecutive phase change cycles in the thermal energy storage systems (TES). Finally, the thermal conductivity of the prepared composites increased up to 27%, compared to that of pure SA.

Investigation of the processes of titanium dioxide dispersion in the presence of various surfactants

Investigation of the processes of titanium dioxide dispersion in the presence of various surfactants

Multifunctional finishing treatments applied on textiles for protection of emergency personnel

The paper presents the results of the researches carried out for obtaining multifunctional textile materials with multiple effects, by means of superior finishing techniques, using functional chemicals in the form of aqueous dispersions. It has been studied the possibility of combining treatment with dispersions with photocatalytic and antibacterial effects with a hydrophobic/oleophobic treatment that simultaneously provides both sustainable photocatalytic and antibacterial effect as well as hydrophobic/oleophobic effect within satisfactory limits for all these effects. The results of the laboratory evaluations performed on 50% cotton and 50% functionalised HT polyamide textile fabrics showed that hydrophobization treatment with fluoropolymer dispersions can be combined with the treatment with titanium dioxide photocalatytic dispersions or silver chloride and titanium dioxide dispersions to obtain multiple photocatalytic, antibacterial and hydrophobic/ oleophobic effects without diminishing the functionalization effects that would have been achieved by individual treatments

Improving titanium dioxide dispersion in water through surface functionalization by a dicarboxylic acid

In this work, we show evidence of improving the dispersion of titanium dioxide particles in water. This is observed in the titanium dioxide-water colloid by the shear-thinning flow behavior in rheological measurements induced by the functionalization of a glutaric acid layer on the surface of titanium dioxide particles. The characterization of the layer was achieved by using infrared spectroscopy and 13 C nuclear magnetic resonance. Rheological measurements corroborated that functionalization of TiO2 particles decreases the rheological properties such as viscosity measurements at a constant shear rate in two orders of magnitude compared with the pure TiO2 in suspensions. We present the results as a novel strategy to limit the formation of agglomerates in these colloidal suspensions, and this will be of great use in applications in the paints field and printing technologies.

EFECTO DE LA MODIFICACIÓN QUÍMICA DE LAS PARTÍCULAS DE DIÓXIDO DE TITANIO MEDIANTE SILANIZACIÓN SOBRE LAS PROPIEDADES DE LAS PELÍCULAS DE CHITOSAN/ALMIDÓN DE PAPA

In this work we present a simple way to improve the dispersion of titanium dioxide (TiO2) particles inside chitosan/potato-starch films by chemical modification of the surface of these nanoparticles via silanization. The films increased in luminosity due to the modified particles, in addition to the fact that the water activity remained within the acceptable values ​​for microbial non-proliferation. The thermal analyzes indicated that the addition of TiO2 increases the glass transition temperature in the film, and the addition of functional groups such as those of the silane, give mobility to the polymer chains during the rise in temperature. The mobility of the polymer is related to a decrease in the value of the temperature necessary to reach a vitreous state in the films that contains silanized particles. The most important result was that the existence of these functional groups reduced the enthalpy of decomposition of the films making them more stable for thermal degradation. The photo-oxidation results suggested the passivate of TiO2 thanks to the presence of silane, which implies that it is a more stable film against UV radiation, avoiding the negative effect of unmodified TiO2 particles.