Rutile Pigments Research Articles

Well-designed submicron rutile pigment heterophase junction photocatalyst via sol-gel method for organic pollutants removal

Well-designed submicron rutile pigment heterophase junction photocatalyst via sol-gel method for organic pollutants removal

Preparation of high near-infrared reflectance mica/(Ni, Sb)-co-doped rutile yellow composite pigment via mechanochemical pretreatment and sintering

Mica/(Ni, Sb)-co-doped rutile yellow composite pigment with a high near-infrared reflectance was prepared via mechanochemical pretreatment and subsequent sintering. (Ni, Sb)-co-doped rutile yellow pigment was synthesized by a solid-phase method in the presence of sodium fluoride (NaF) as a mineralizer, and mica was peeled by ultrafine grinding. The pigment, mica and mica/pigment composite were characterized by X-ray diffraction, laser diffraction particle size analysis, nitrogen gas adsorption method, scanning electron microscopy, energy dispersive spectroscopy, ultraviolet–visible–near-infrared spectroscopy, CIEL*a*b* color scales, and infrared irradiation image, respectively. The results show that the temperature of synthesizing a pure rutile pigment in solid-phase reaction is reduced by 100°C due to the addition of mineralizer NaF. (Ni, Sb)-co-doped rutile pigment has better color rendering performance and near-infrared (NIR) reflectance. Ultrafine grinding produces the finer flatty mica particles with fresh reflective surfaces, thus improving NIR reflectance of peeled mica. In mica/pigment composite prepared via mechanochemical pretreatment and subsequent sintering, peeled mica has a synergistic effect on (Ni, Sb)-co-doped rutile pigment particles to further scatter near-infrared radiation through the multiple layer reflections, leading to a better heat insulation. The high near-infrared reflectance of composite pigment increases to 97.72%, and the b* value of the pigment synthesized with 1 wt% NaF is 37.77. For the irradiation infrared lamp, the surface temperature of aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is 40.1 ± 0.2°C, which is lower than that of aluminum plate uncoated determined by thermal camera and thermocouple. When aluminum plate coated with mica/(Ni, Sb)-co-doped rutile yellow composite pigment is under sunshine, its surface temperature is 38.6 ± 0.2°C. In addition, the mechanism of preparing the composite pigment via mechanochemical pretreatment and subsequent sintering and the multiple structure reflection effect on peeled mica surface coated with (Ni, Sb)-co-doped rutile yellow pigment particles were also discussed.

Consideration of Photoactivity of TiO2 Pigments via the Photodegration of Methyl Orange under UV Irradiation.

Developing a rapid and reliable method for measuring the photoreactivity of TiO2 pigments is of great importance for industrial application. The photoactivity of industrial TiO2 pigments were evaluated via the photodegradation of a model azo dye, methyl orange (MO), in the present work. The TiO2 pigments were characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis) spectroscopy, scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. The photoactivity test results showed that the anatase TiO2 pigment was responsible for accelerating MO degradation, while the rutile pigment acted as a stabilizer, and effective UV absorber retarded the photodegradation of MO. It was found that the photodegradation of MO was driven mainly by photoholes (h+) and hydroxyl radicals (•OH), in the presence of TiO2 pigment with high photoactivity. With the help of the degradation intermediates during the photodegradation process and the calculated data, the preliminary degradation mechanism including azo bond cleaving, h+ oxidation, and hydroxylated products’ generation for MO was also elucidated. The photoactivity of TiO2 pigments can be rapidly evaluated in this work, which would be an efficient approach for assessing the product quality control and the end-use performance of TiO2 pigments.

Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments.

Rutile TiO2 pigments codoped with chromophore ion Cr3+ and various charge-balancing ions (i.e., counterions species of Sb, Nb, W and Mo) were prepared by a solid-phase reaction method. The effects of the counterions and calcination temperatures on the phase structure, color-rendering and spectroscopic properties, microstructure, and stability of the synthesized pigments were investigated in detail. The results showed that the introduction of 5–10% counterions improved the solubility of Cr3+ in the TiO2 lattice to form the single-phase rutile pigments calcined at 1100 °C for 2 h. The 10% Cr-doped pigment showed a dark brown color. Depending on the content and type of counterions, the color of the codoped pigments was tailored from yellow to reddish or yellowish-orange to black with different brightness and hue. The influence mechanism of counterions was ascribed to the lattice distortion and variation in the charge balance condition. It was found that the addition of Sb, Nb, or Mo resulted in a remarkable improvement in the NIR reflectance of pigments. The grain growth was inhibited with the codoping of Cr/Sb and Cr/Nb to achieve the nano-sized pigments. In addition, the prepared pigments exhibited good acid and alkali corrosion resistance as well as excellent stability and coloring performance in transparent ceramic glazes.

Effects of Structural Factors of Hydrated TiO2 on Rutile TiO2 Pigment Preparation via Short Sulfate Process

The structural factors such as crystal structure, particle size distribution and impurity content of hydrated TiO2 had great effects on the structures and pigment properties of the rutile TiO2. The rutile TiO2 white pigment was prepared via the Short Sulfate Process from low concentration industrial TiOSO4 solution. In order to produce rutile TiO2 pigment with good structures and excellent pigment properties, the crystal size of the hydrated TiO2 should be controlled less than 8.9 nm and as close as possible to 7.9 nm, which could effectively promote the phase transformation and crystal growth of the rutile TiO2. The appropriate particle size distribution of hydrated TiO2 had obvious effects on obtaining rutile TiO2 with narrower particle size distribution and near 0.20 µm. It was best to adjust the hydrolysis conditions to reduce the specific surface area of the hydrated TiO2 so as to reduce the iron ion impurity adsorption.

Titanium Silicates Precipitated on the Rice Husk Biochar as Adsorbents for the Extraction of Cesium and Strontium Radioisotope Ions

The aim of the work was the development of cheap and effective adsorbents based on titanium silicates deposited on the products of thermochemical processing of rice husk to extract cesium and strontium radioisotopes from aqueous media. Synthesis of adsorbents was carried out using the cheapest and widely used titanium water-soluble reagent, titanium sulfate (an intermediate product of white rutile pigment production), as feedstock. After treatment with titanium sulfate and neutralization, hydrothermal treatment was carried out in various ways. The traditional method of processing in an autoclave was used, as well as the blowing at different temperatures by steam. The distribution coefficients and the adsorption capacity for cesium and strontium ions on these sorbents were studied. Along with the chemical composition of adsorbents obtained by those ways, the type and the temperature of hydrothermal treatment also affected the adsorption properties. It was found that the adsorbent obtained by hydrothermal treatment in an autoclave has the highest degree of cesium ions extraction (Kd = 27,500). The highest degree of strontium ions extraction (Kd = 2,095,000) has an adsorbent obtained by hydrothermal treatment with water vapor blowing.

A spectroscopic method for quick evaluation of tint strength and tint tone of titania (rutile) pigment and factors affecting them

AbstractTitanium dioxide (TiO2) manufacturing industries measure optical properties such as brightness, colour, tint strength, tint tone, gloss, scatter coefficient, and others to ensure the quality of the product. Product characterization and process control generally focus on the optical properties, which determine its quality. In this work, titania rutile pigment with varying tint strength and tint tone is analyzed and a correlation is established between particle size and the optical properties such as tint strength and tint tone. It is observed that optical properties of titania pigment depends on the particle size as well as particle size distribution. A relatively faster evaluation of tint strength and tint tone can be made using the reflectance and particle size measurements. Analytical samples were prepared by ultrasonic dispersion of pigment in water containing calgon as dispersing agent. To verify the accuracy of the method, pigment tint strength and tint tone obtained from this study are compared with those resulting from traditional analysis. The results showed that the new method is viable.

Surface properties of recycled titanium oxide recovered from paint waste

Aluminium oxide coated rutile pigment was extracted from a paint matrix by means of a thermal recycling process. The objective was to investigate the effect of the recycling process on the surface properties of the pigment. The pigment was analysed using powder x-ray diffraction (XRD), surface area measurements (BET), laser diffraction for particle size analysis and X-ray photoelectron spectroscopy (XPS) before and after the recycling process. Investigations on the zeta potential and the surface charge were performed as well. It was concluded that the rutile crystalline core and the aluminium oxide coating of the pigment were still intact after the recycling process. The particle size distribution of the recycled pigment was slightly broader compared to the virgin pigment. The measured magnitude in zeta potential of the recycled pigment was lower than for the virgin pigment. This difference is thought to be caused by alteration in the surface hydroxyl concentration. Surface charge titrations showed differences between the virgin and the recycled pigment at alkaline pH and at low salt concentrations.

Characterisation of silicon, zirconium and aluminium coated titanium dioxide pigments recovered from paint waste

Titanium dioxide (TiO2) is the major white pigment used by the paint industry. However, the production of TiO2 is associated with a high carbon footprint. An alternative source of pigment could be created by developing a method to recover it from waste paint. In this paper two rutile pigments with different surface treatments were recovered from paint by a thermal recycling process. The pigments were analysed using powder x-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), surface area measurements (BET), laser diffraction for particle size analysis and zeta potential measurements before and after the recycling process. It was concluded that the rutile cores of both pigments were intact and there were no major changes in particle size distribution or surface charge for either pigment induced by the recycling process. However, XPS and zeta potential measurements showed that the surface coating of the pigments can be more or less degraded depending on the chemical nature, which might imply the need for further re-coating after-treatment. Another option would be to find another application for the pigment where the quality and function of the coating is of less importance.

Is it time for routinely tracking of early immunosuppression in tracking and prognosing patients with acute pancreatitis?

(Ni, Sb)-co-doped rutile yellow ceramic pigments were synthesized via a mechanical activation-assisted solid-state reaction in a stirred bead mill. The effects of mechanical grinding of the raw materials on the synthesis of (Ni, Sb)-co-doped rutile pigment were investigated. The results show that mechanical activation effectively decreased the crystallinity of the mixed precursors, thus enhancing their reactivity and the migration rate of ions. These effects lowered the temperature required for formation of the rutile phase. Compared with results from a mixture of separately ground precursors, the mixture of raw materials ground together was more effective for accelerating nickel/antimony ions doping into the TiO2 structure and improved the color performance of the pigment. The pigment from the mixed raw materials ground for 2.0 h and heat-treated at 1100 °C could be used as an environmentally-friendly ceramic yellow pigment owing to its low-toxicity, bright yellow hue, good chemical/thermal durability, and high cost-effectiveness.

Synthesis and characterization of (Ni, Sb)-co-doped rutile ceramic pigment via mechanical activation-assisted solid-state reaction

(Ni, Sb)-co-doped rutile yellow ceramic pigments were synthesized via a mechanical activation-assisted solid-state reaction in a stirred bead mill. The effects of mechanical grinding of the raw materials on the synthesis of (Ni, Sb)-co-doped rutile pigment were investigated. The results show that mechanical activation effectively decreased the crystallinity of the mixed precursors, thus enhancing their reactivity and the migration rate of ions. These effects lowered the temperature required for formation of the rutile phase. Compared with results from a mixture of separately ground precursors, the mixture of raw materials ground together was more effective for accelerating nickel/antimony ions doping into the TiO2 structure and improved the color performance of the pigment. The pigment from the mixed raw materials ground for 2.0h and heat-treated at 1100°C could be used as an environmentally-friendly ceramic yellow pigment owing to its low-toxicity, bright yellow hue, good chemical/thermal durability, and high cost-effectiveness.

Preparation and thermal reflectivity of nickel antimony titanium yellow rutile coated hollow glass microspheres composite pigment

In order to reduce the urban heat island effect, nonwhite lightweight pigments with high near infrared reflectance were studied. Nickel Antimony Titanium Yellow Rutile pigments (TiNiY) coated hollow glass microspheres (HGM@TiNiY) with core-shell structure were prepared by a novel mixing slurry-sintering method. The Reflective property of HGM@TiNiY/SR composite coating prepared by mixing HGM@TiNiY with silicone resin (SR) was investigated by an UV–Vis–NIR spectrum analyzer. The results showed that the size distribution of TiNiY particles was from 150 to 450 nm with an average size of 230 nm, and the binding mode of TiNiY particles with HGM and the formation mechanism of TiNiY Shell were discussed. The UV–Vis–NIR reflectance of HGM@TiNiY/SR coating was not only better than that of others filled with HGM powders or TiNiY powders alone but also higher than that of the coating filled with the mixture of HGM and TiNiY powders at the same volume ratio. A possible mechanism of HGM@TiNiY/SR coating on thermal reflection was discussed. This clearly indicates that the pigment of HGM@TiNiY with core-shell structure could be applied as a good colour cool pigment.

Calcination intensity on rutile white pigment production via short sulfate process

The rutile titanium dioxide pigment was produced via short sulfate process from unenriched industrial titanyl sulfate solution as raw material. The effects of calcination intensity after crystal transformation on the crystal structure, particle size distribution and pigment performances were investigated. The samples were characterized by TG-DSC, XRD, SEM, particle size distribution test and pigment properties test. The crystal grain size and content for rutile pigment gradually grew as the calcination intensity increasing, with a positive linear correlation. While the blue phase index is negative linear correlation with calcination time. The optimized calcining time at 860 °C for rutile pigment production is of 40 min, corresponding calcination intensity of 1,34,277 K min, and the as-prepared rutile pigment is with the grain size of 110.8 nm, rutile content of 98.3%, suitable and narrow particle size distribution, and the best pigment performances.

Transformation between Antase and Rutile Titania-Mica Pearlescent Pigment by MnO<sub>2</sub> Induced Process

A chemical inducing process was developed to prepare titania-mica pearlescent pigment. MnO2 was used as crystal inducing promoters, a transformation between antase and rutile titania-mica pearlescent pigment was found by calcining at 800°C for 0.5 h. The mass ratio of mica to MnO2, pH value, temperature and dripping rate of MnO2solution and TiOSO4was studied. The crystalline form of titania-mica pearlescent pigment was measured by XRD.

Synthesis and Characterization of Rutile Pigments with Cr and Nb

Rutile pigments Ti1-3xCrxNb2xO2±δ (where x=0, 0.05, 0.10, 0.20, 0.30 and 0.50) prepared by solid-state reaction are investigated. Chromium is chromophore (coloring ion) and niobium is counterion (charge-compensating element for electroneutrality). The effect of composition (x), calcination temperature (850, 900, 950, 1000, 1050, 1100 and 1150°C), and starting titanium compounds (anatase TiO2, hydrated anatase paste, TiOSO4·2H2O, and hydrated Na2Ti4O9 paste) on their color properties into organic matrix and particle size distribution was observed. According to the highest chroma C and visual color evaluation, yellow and orange pigments were selected as in color the most interesting. They have concentration x=0.05 or 0.10 and are prepared from anatase TiO2 and TiOSO4·2H2O at temperature ≥1050°C.

Effects of Pre-Adding Water Volume Ratio on Rutile White Pigment Production via Sulfate Short Process

Using unconcentrated industrial TiOSO4 solution as raw material, rutile TiO2 white pigment was prepared via the self-seeded thermal hydrolysis sulfate process. The effects of pre-adding water volume ratio on the hydrolysis process and pigment properties of the TiO2 white pigments were investigated. The samples were characterized by XRD, particle size distribution and pigment properties test. The pre-adding water volume ratio had great effects on the quantity and active of seed crystal, hydrolysis process, eventually determined particle size distribution and its pigment properties. The optimized pre-adding water volume ratio was of 0.22. The as-prepared rutile white pigment was with appropriate particle size, narrow particle size distribution and good pigment properties.

Effects of Initial Feed Speed of 1 Min on Rutile White Pigment Production via Short Sulfate Process

Hydrolysis is one of the crucial steps in the product of titanium white pigment via sulfate process, and determines quality of the final products. Feed Speed have important effect to the quality and the numbers of seeds of early hydrolyzing. Using low concentration TiOSO4 as raw materials, fine rutile white titanium pigment was prepared by optimizing the key parameters of the hydrolysis process via the achromatic force and the level of whiteness of the samples. The samples were characterized by SEM, particle size distribution and pigment properties test. Resultes have shown that the feeding speed of 1 min is 1.1times to the speed after 1 min. In this conditions, the obtained titanium white pigment showed better pigment performance.

The effects of particle size distribution on the optical properties of titanium dioxide rutile pigments and their applications in cool non-white coatings

The particle size distributions of three commercially available titanium dioxide pigments were measured, and their effects on the optical properties of the pigments were investigated. The Altiris 550 and 800 pigments possess larger median particle size and wider size distributions than those of the conventional titanium dioxide rutile. The visible (VIS) reflectance, the solar reflectance and the lightness of the films and coatings singly pigmented with any of these three pigments decrease as the pigment particle size increases. The VIS transmittance and near-infrared (NIR) reflectance both increase as the pigment particle size increases. The main reflection band of the coatings shifts farther into the NIR region with increasing pigment particle size. The partially VIS-transmitting Altiris pigments enable the NIR and the solar reflectance of cool non-white coatings to be improved, thereby yielding metameric matches to the desired colors.

Hydrolysis Time on Rutile TiO<sub>2</sub> White Pigment via Short Sulfate Process

Rutile TiO2 white pigment was prepared by self-seeded thermal hydrolysis route via short sulfate process from low concentration TiOSO4 solution. Hydrolysis time had significantly influenced the structure and pigment properties of rutile TiO2. The samples were characterized by XRD, particle size distribution and pigment properties test. The hydrolysis time had great influences on the hydrolysis rate, particle size distribution, crystal growth and particle aggregation of TiO2, eventually determined the pigment structure and properties. The optimized hydrolysis time after second boiling point was of 2.5h. And the prepared rutile TiO2 white pigment was with narrow particle size distribution and nice pigment properties.

Highly dispersed (Cr, Sb)-co-doped rutile pigments of cool color with high near-infrared reflectance

Highly dispersed (Cr, Sb)-co-doped rutile nonwhite pigments with high near-infrared (NIR) reflectance were prepared by introducing dispersants during precursor hydrolysis. The pigment properties were investigated by X-ray diffraction, scanning electron microscopy, X-ray photoemission spectroscopy, diffuse reflectance spectroscopy, Raman spectroscopy, and colorimetry. The pigments had rutile phase composition and narrow size distributions of 0.5 μm–1 μm after calcination at 700 °C. Co-doping with Cr and Sb restrained the generation of hexavalent chromium in the rutile lattice. The co-doped pigments had good color properties and high NIR reflectance because of the absence of Cr6+. The pigments had high tinting strength, and a good hue for PE flake was attained by adding 1% pigments. An approximately 10 °C decrease in temperature was obtained for the inner surface of ceramic tiles coated with the co-doped pigments under 30 min of irradiance.