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Concrete is the favored construction material, with more than 7 billion cubic meters manufactured annually. Aggregates constitute the crucial component of its structure and quality, responsible for its exceptional characteristic features. The characteristics of aggregates determine the mechanical durability and radiation performance of concrete. In this investigation, fabricated concrete specimens were generated by replacing sand and aggregate sizes with pyrophyllite in 10%–20%–30%–100% proportions. The study investigated the mechanical properties of concrete specimens using both pressure and ultrasound methods, as well as their durability under freeze–thaw and high-temperature (200°C–1,000°C) conditions. In addition, the microstructure and radiation permeability properties were examined over a 7–28–90-day period. Notably, the use of pyrophyllite sand and aggregate significantly increased the compressive strength of the specimens by 21%–63% when compared to the reference concrete after 7–28–90 days, while also reducing mass loss by up to 4.6% during freeze–thaw cycles. After subjecting the specimens to high temperatures, it was discovered that those with an air-cooling regime achieved a compressive value 45% higher than the reference concrete. Microstructure images revealed the formation of C─ S─ H, CH, and portlandite hydration products over 90 days, supporting the observed compressive strength values. The study also has an effective linear attenuation coefficient (LAC) for radiation-shielding properties. According to some radiation-shielding parameters calculated through LAC values, it was revealed that these concrete samples were suitable shielding materials. Pyrophyllite-reinforced specimens have demonstrated potential for high-strength concrete production, suitability for use in high-temperature environments, and effectiveness as shielding in areas with radiation sources. [ABSTRACT FROM AUTHOR]

The widespread use of clay minerals and clays in environmental engineering, industry, medicine, and cosmetics largely stems from their adsorption properties and surface charge, as well as their ability to react with water. The dissolution and growth of minerals as a function of pH are closely related to acid–base reactions at their surface sites and their surface charge. The vivid tapestry of different types of surface sites across different types of clay minerals generates difficulties in experimental studies of structure–property relationships. The aim of this paper is to demonstrate how a mesoscale stochastic kinetic Monte Carlo (kMC) approach altogether with atomistic acid-base models and empirical data can be used for understanding the mechanisms of dissolution and surface charge behavior of clay minerals. The surface charge is modeled based on equilibrium equations for de/protonated site populations, which are defined by the pH and site-specific acidity constants (pKas). Lowered activation energy barriers for these sites in de/protonated states introduce pH-dependent effects into the dissolution kinetics. The V-shaped curve observed in laboratory experiments is reproduced with the new kMC model. A generic rate law for clay mineral dissolution as a function of pH is derived from this study. Thus, the kMC approach can be used as a hypothesis-testing tool for the verification of acid–base models for clay and other minerals and their influence on the kinetics of mineral dissolution and growth. [ABSTRACT FROM AUTHOR]

Mullite ceramics with high purity and toughness were prepared by hot‐press sintering of pyrophyllite at 1300°C using AlOOH nanomaterials with different sizes and morphologies (nanoparticles, nanorods, nanoflakes, and micro‐sized sea urchin–like) as additives. Among the four types of AOOH additives, the incorporation of nanoflakes and sea urchins resulted in the formation of a relatively uniformly distributed and tightly packed microstructure within the ceramics, which significantly improved the density and mechanical properties of the ceramic materials. Compared to nano‐sized AlOOH, the addition of micron‐sized sea urchin–like AlOOH could produce mullite ceramics with best purity and flexural strength. The flexural strength and fracture toughness of ceramics prepared from micro‐sized sea urchin–like AlOOH and pyrophyllite reach 427.34 ± 1.99 MPa and 4.68 ±.31 MPa m1/2, respectively. During the ball milling process, the originally micron‐sized sea urchin–like AlOOH particles were broken down into micro‐ and nano‐sized AlOOH particles. The resulted micron and nanoscale AlOOH particles exhibited synergistic and multi‐scale effects with pyrophyllite, which contributed to the formation of uniformly sized and densely arranged mullite crystals within the ceramics. Additionally, the bridging between the mullite crystals further improved the mechanical properties of the mullite ceramic material. [ABSTRACT FROM AUTHOR]

ObjectivesPyrophyllite, as a sealed pressure medium, has been widely used in high-pressure research for laboratories and industrial synthesis. A highly efficient pressure transfer medium can generate higher cell pressure at the same loading force. The use of a highly efficient pressure transfer medium reduces the risk of anvil rupture and production costs. Therefore, it is important to develop a suitable and efficient pressure-transmitting pyrophyllite.MethodsThe pressure calibration of four pyrophyllites from different localities at room temperature was conducted in a 6 × 8 MN multi-anvil large-volume press. The relationship between loading force and cell pressure at room temperature was established. The influence of mineral composition changes in pyrophyllite on pressure-transmitting efficiency was studied using X-ray diffraction.ResultsBy investigating the influence of mineral composition changes in pyrophyllite on pressure-transmitting efficiency, the results are as follows: (1) When achieving the same cell pressure, the required loading force for Pyrophyllite 4 is 10% lower than those for the other three pyrophyllites, indicating that Pyrophyllite 4 has the best pressure-transmitting efficiency. (2) As cell pressure increases, the relationship between cell pressure and loading force begins to deviate from linearity, and the pressure-transmitting efficiency of pyrophyllite gradually decreases. When the cell pressure exceeds 5.00 GPa, applying higher loading force does not significantly increase the cell pressure. (3) Higher hardness minerals (such as Diaspore, Boehmite) in pyrophyllite can effectively improve pressure-transmitting efficiency in the low-pressure stage (cell pressure 2.55-3.68 GPa). When the minerals in pyrophyllite undergo phase transformation to form new minerals with higher hardness (such as Muscovite and Kaolinite) in the high-pressure stage (cell pressure of 5.50 GPa), pressure-transmitting efficiency can be effectively improved.ConclusionsPyrophyllite 4 has better pressure-transmitting efficiency than Pyrophyllite 2 does in the high-pressure stage, but it is prone to failure in sealing due to the changes in mineral composition. However, Pyrophyllite 2 shows good elastic recovery effect and sealing performance and can stably complete compression and decompression work. Considering both pressure-transmitting efficiency and sealing effect, Pyrophyllite 2 has better application value and economic benefits.

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Owing to its unique properties, pyrophyllite is an economical alternative to many minerals in different applications. The presence of iron-bearing minerals in Saudi pyrophyllite hampers its industrial uses. The aim of this study was to examine the removal of iron from Saudi low-grade pyrophyllite ore using two approaches. The first approach involves dry high-intensity magnetic separation, whereas the second approach involves microwave pretreatment of the ore before dry magnetic separation. For the first approach, the studied operating parameters were roll speed; feed rate, field intensity, and feed particle size. For the alternative approach, microwave treatment followed by dry magnetic separation, the microwave irradiation time and the magnetic field intensity were studied. The results show that the combined microwave treatment and dry separation method could provide high-purity pyrophyllite for filler industries. Microwave irradiation for 30 min was optimal to change impurity phases (i.e., pyrite, hematite) into ferromagnetic phases in microwave-treated pyrophyllite samples. At a magnetic field intensity of 2000 Gauss, the 30 min microwave-irradiated pyrophyllite sample achieved an iron recovery of 11.2% in non-magnetic fractions, with a removal efficiency of 89% with an alumina recovery of 91.31%. [ABSTRACT FROM AUTHOR]

This research investigates the fabrication of porous mullite filter material from reaction sintered mullite grains for high-temperature applications. Current filter types are not suitable for application in high-temperature and corrosive environments despite their high porosity. Acicular Mullite Ceramics are known for their highly porous microstructures with excellent mechanical integrity. Fabrication of a rod-like porous mullite filter from mullite grains produced from pyrophyllite clay and Al2O3 via reaction sintering was investigated. Pure mullite phase was produced at 1600 °C, and the use of a binder and foaming agent helped to obtain a porous structure. Above 1700 °C, acicular mullite grain growth via two-dimensional heterogeneous nucleation was promoted. A friable and structurally poor material was produced at temperatures just below 1800 °C. Above 1800 °C, the structural integrity of the ceramic material was improved. The measured total porosity and average pore diameter at 1800 °C were 36.20% and 29.32 µm, respectively. The measured density was 1.99 g/cm3, and the average compressive strength was 12.60 MPa. The characteristic strength was 14.49 MPa, with a Weibull modulus of 2.67. [ABSTRACT FROM AUTHOR]

Kaolin (mainly composed of kaolinite, whose chemical formula is Al2Si2O5(OH)4), serves as a versatile raw material widely used in various industries including production of ceramics, paper, paints, cosmetics, pneumatics, building materials, and hazardous waste storage. In the northern part of Vietnam, due to favorable geological conditions, there are diverse deposits of high quality kaolin of different origin and scale. Decades of research indicate the diversity of kaolin sources in the region, with special attention paid to hydrothermally altered and exchange types of kaolin, the formation of which is associated with complex processes of weathering, hydrothermal alteration and reprecipitation. The aim of this study was to characterize three different types of kaolin derived from different sources in Northern Vietnam (from weathered pegmatites, weathered felsic effusives, and hydrothermal-metasomatic altered rocks). The main focus was to analyze the thermal behavior of these samples during calcination in the temperature range from 300 °C to 1,100 °C. The comprehensive characterization was performed by X-ray diffraction (XRD), FT-IR spectroscopy (FT-IR), thermal analysis (thermogravimetry / differential thermogravimetry (TG / DTG)) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The results showed that kaolinite with particle size less than 2 μm was identified in all samples. Minor amounts of muscovite and montmorillonite are present in some samples, and pyrophyllite is present in a sample from the hydrothermally altered rocks. Kaolinite morphology in all the samples showed typical forms including hexagonal and pseudohexagonal. The main chemical constituents of the samples are SiO2 and Al2O3; in addition to these, K2O + Na2O, TiO2 and iron are present in smaller quantities. Thermal analysis allowed to reveal the formation of metakaolinite phase at temperatures around 494 °C and 507 °C in the two studied samples from weathered rocks, while the pyrophyllite-bearing sample undergoes this transition at a higher temperature of 653.8 °C. The onset of metakaolinization was observed at about 500 °C for the weathered rock samples and about 700 °C for the pyrophyllite-bearing sample. In addition, mullitization leading to the formation of mullite was evident at 1,100 °C. The study findings allow concluding that the studied kaolins can be used in traditional ceramics production.

Ceramic polymer materials have great future applications in the field of fireproof materials. However, ceramic polyolefins have shortcomings such as few available inorganic fillers, high sintering temperature, and low flexural strength. Therefore, achieving rapid sintering of ceramic ethylene‐propylene‐diene rubber (EPDM) is an urgent problem that needs to be solved. Herein, we prepared ceramic EPDM materials using pyrophyllite as aggregate and zinc borate as flux. The materials were prepared using a mixer and sintered in a muffle furnace at 850 and 1000°C. The flexural strength of the sinter residue was tested by a material testing machine. The microstructure changes during the ceramification process were characterized using scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric analysis (DTG), differential thermal analysis (DTA), and x‐ray diffraction (XRD). The results indicated that the EPDM filled with pyrophyllite and zinc borate had a flexural strength of 2.6 MPa after sintering at 850°C. After sintering at 1000°C, its flexural strength further increased up to 12.3 MPa. The SEM results indicated that as the temperature increased, the zinc borate melted and filled in the space among pyrophyllite particles, and the zinc borate and the pyrophyllite were sintered into a dense whole. The TG, DTG and DTA testing results indicated that the melting and decomposition behaviors of the pyrophyllite‐zinc borate mixture changed compared with pure pyrophyllite and zinc borate. The XRD results indicated that during the sintering process, the crystalline structure of the zinc borate and the pyrophyllite gradually transformed into a quartz‐based crystalline structure. It is promising that the ceramic polyolefin materials are prepared by the pyrophyllite/zinc borate combination. [ABSTRACT FROM AUTHOR]

Owing to its unique properties, pyrophyllite is an economical alternative to many minerals in different applications. The presence of iron-bearing minerals in Saudi pyrophyllite hampers its industrial uses. The aim of this study was to examine the removal of iron from Saudi low-grade pyrophyllite ore using two approaches. The first approach involves dry high-intensity magnetic separation, whereas the second approach involves microwave pretreatment of the ore before dry magnetic separation. For the first approach, the studied operating parameters were roll speed; feed rate, field intensity, and feed particle size. For the alternative approach, microwave treatment followed by dry magnetic separation, the microwave irradiation time and the magnetic field intensity were studied. The results show that the combined microwave treatment and dry separation method could provide high-purity pyrophyllite for filler industries. Microwave irradiation for 30 min was optimal to change impurity phases (i.e., pyrite, hematite) into ferromagnetic phases in microwave-treated pyrophyllite samples. At a magnetic field intensity of 2000 Gauss, the 30 min microwave-irradiated pyrophyllite sample achieved an iron recovery of 11.2% in non-magnetic fractions, with a removal efficiency of 89% with an alumina recovery of 91.31%.

Mycotoxins are a large and chemically diverse group of toxic secondary metabolites. Regarding their prevalence in animal feed and the effect on animal health, the biggest problems in terms of safety and economic losses are caused by aflatoxins, fumonisins, ochratoxins, trichothecenes and zearalenone. Adsorbents are substances that are added to food contaminated with mycotoxins, in order to bind them in the gastrointestinal tract and thereby prevent or reduce their effect. The aim of this study was to examine the possibility of using pyrophyllite as a mineral adsorbent, as well as preparations made of ground peach pits of different particle sizes as organic adsorbents, for adsorption of deoxynivalenol and ochratoxin A. Mycotoxin adsorption experiments were performed in vitro in electrolyte solutions at pH 3 and 7. The adsorption efficiency of the adsorbent was expressed as adsorption index. Pyrophyllite had adsorption index ​​of 13.47% for ochratoxin A at pH 3, while at pH 7, as well as for deoxynivalenol, the same mycotoxin produced a negligible degree of adsorption. Ground peach stones (of larger diameter, d = 0.1 mm) had considerable adsorption rates for ochratoxin A at pH 3 (34.41%) and deoxynivalenol at pH 7 (18.57%). The values were similar for smaller diameter (d < 0.1 mm) for ochratoxin A at pH 3 (42.71%) and deoxynivalenol at pH 7 (20.11%). The obtained results suggest that the potential of the preparation of ground peach stones for the adsorption of tested mycotoxins is higher compared to the potential of pyrophyllite, but there are differences in their efficiency depending on the pH value of the adsorption environment.

The Bundelkhand Craton located in the northern part of the Indian Shield had been subjected to polyphase deformation and polyphase metamorphism in several episodes from Archaean to early Proterozoic times. The Craton comprises pyrophyllite-diaspore deposits mainly along the NE-SW trending shear system indicated by prominent quartz reefs where intense silicification has taken place during hydrothermal alteration. In the present study, the ASTER images were analyzed to demarcate the pyrophyllite deposits in the Tikamgarh based on the spectral characteristics of pyrophyllite with a strong absorption peak of 2.165 μm. The band ratio, band math images from ASTER data and the sub-pixel classifications of pyrophyllite were adopted by using Linear Spectral Unmixing (LSU) and Mixture Tuned Matched Filtering (MTMF) algorithm. The combination of these methods could detect the mineable pyrophyllite deposits more accurately. This approach along with field geological observations, petrological and chemical analyses could differentiate the high-grade and low-grade pyrophyllite more easily. It could provide information regarding the probable pyrophyllite mining activity. This research has also aided knowledge to investigate similar types of deposits anywhere in the world. [ABSTRACT FROM AUTHOR]

Copyright of Archives of Veterinary Medicine / Arhiv Veterinarske Medicine is the property of Scientific Veterinary Institute Novi Sad and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, the effect of different beneficiation methods on aluminum recovery from pyrophyllite ore was investigated. Flotation method was used due to the naturally hydrophobic structure of pyrophyllite, and Attrition Scrubbing (AS) methods was used due to the difference in fragility. As a result of the beneficiation, concentrated samples were leached with HCl, and the amount of Al transferred to the solution as a result of the leaching was compared and evaluated. As a result of the beneficiation of the pyrophyllite ore with the AY method, a concentrate with a grade of 27.44% Al2O3 with a recovery of 54.79%, and a concentrate with a grade of 28.05% Al2O3 with a recovery of 30.49% by the flotation method. Accordingly, it was determined that the attrition scrubbing method was more efficient in terms of beneficiation efficiency, while the flotation method was more efficient in terms of leaching efficiency. When the final alumina amount and purity according to the raw ore were evaluated together, it was determined that the values of direct leaching and AY concentrate were close to each other. As a result, it is considered that it would be more accurate to determine the appropriate method by performing detailed economic analysis for the production of alumina from pyrophyllite ore. [ABSTRACT FROM AUTHOR]

Pyrophyllite is an important layered phyllosilicate material that is used in many fields due to its beneficial physicochemical and mechanical properties. Due to the presence of multiple defects in pyrophyllite, an in-depth investigation was conducted using density functional theory to explore the effects of Na(I), K(I), Mg(II), Ca(II) and Fe(II) doping on the atomic structure, electronic properties and mechanical characteristics of pyrophyllite. The results demonstrated that, among the studied defects, K(I) doping had the most pronounced effects on the lattice constants and bonding lengths of pyrophyllite, while the least significant effects were observed in the case of Fe(II) doping. Moreover, the partial and total densities of states and band structures of the five kinds of doped pyrophyllite also changed significantly due to the redistribution of electrons. Finally, the elastic constants of the doped pyrophyllite were lower than that of the undoped pyrophyllite. Doping with Na(I), K(I), Mg(II), Ca(II) and Fe(II) reduced the deformation resistance, stiffness and elastic wave velocity but increased the degree of anisotropy in pyrophyllite. The observed effects on the mechanical properties of pyrophyllite followed the order: Mg(II) > Fe(II) > Ca(II) >K(I) > Na(I). [ABSTRACT FROM AUTHOR]

High‐toughness mullite ceramics were fabricated through hot‐press sintering (HPS) of pyrophyllite and AlOOH, which were wet‐milled and well mixed using a planetary ball mill. The impacts of sintering temperatures and contents of AlOOH on mullite phase formation, densification, microstructure and mechanical properties in ceramic materials were investigated through XRD, SEM and mechanical properties determination. The results indicated that high‐toughness mullite ceramics could be successfully prepared by HPS at temperatures higher than 1200°C for 120 min. Increasing the sintering temperature from 1000 to 1300°C significantly enhanced the flexural strength and fracture toughness of samples. The highest flexural strength of 297.97±25.32 MPa and fracture toughness of 4.64±0.11 MPa⋅m1/2 were obtained for samples sintered at 1300°C. Further increase of temperature to 1400°C resulted in slight decrease of flexural strength and fracture toughness. Compared with the mullite ceramics prepared only using pyrophyllite as raw material, incorporation of AlOOH into raw material significantly increased the mechanical properties of final mullite ceramics. And stoichiometric AlOOH and pyrophyllite as starting material gave the best performance in fracture toughness. The high‐toughness of mullite ceramics were ascribed to the high mullite phase content, fine mullite whiskers and in situ formed, intertwined three‐dimensional network structure obtained through HPS at a low temperature of 1300°C. [ABSTRACT FROM AUTHOR]

Clays, inorganic materials with layered crystal structure, are widely used as a pharmaceutical excipients and active substances. The pyrophyllite, Al2Si4O10(OH)2, is an aluminosilicate mineral, that together with talc belongs to a specific sub-clay group. In this study, we examined some aspects of the use of pyrrophylite as a talc substitute. In this study, two pyrophyllite modifications have been investigated: the original pure pyrophyllite (labeled as PYRO), and that modified by incorporation of nanodispersed silver (labeled as PYRO/Ag). For pyrophyllite application in medicine, its thermal stability is of great importance. As an accelerated study of thermal stability, we employed simultaneous thermogravimetry and differential thermal analysis (TG/DTA) methods in dynamic (non-isothermal) regime in inert (N2) atmosphere. Pyrophyllite clay decomposition has been proved to proceed in two steps: moisture removal (I stage) and dehydroxilation (II stage). It must be stressed that these two degradation stages are not strictly separated. The kinetic parameters of decomposition reactions were examined by both isoconversional and model-fitting analytical procedures. The isoconversional Friedman model amounted activation energy (Ea) value on 65 kJ mol−1 and 214 kJ mol−1 for vaporization and dehydroxilation process, respectively. Fitting procedure revealed that vaporization process is of the n-th order (with activation energy, frequency factor and reaction order Ea = 66.6 kJ mol−1, A = 3.05 × 108 s−1, n = 3, respectively), while the dehydroxilation process, is best described with distributed activation energy models (Discrete: Ea = 232.2 kJ mol−1 (50.1%), with initial minimum frequency factor 3.66 × 109 s−1 and initial maximum frequency factor 3.66 × 1011 s−1). In addition to thermal properties, antimicrobial activity of pure (PYRO) and modified pyrophyllite (PYRO/Ag) were tested. Modified PYRO/Ag showed excellent antimicrobial properties, providing sterile conditions against Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. The minimum bactericidal concentration (MBC) of Ag was found to be 25 mg L−1. [ABSTRACT FROM AUTHOR]

Nanocomposites of TiO2-clay were synthesized by the sol–gel route. The materials were characterized by XPS, XRD, UV–Vis DRS and BET surface area. Photocatalytic activity under UV irradiation (λmax ≈ 365 nm) was investigated by means of the phenol oxidation reaction. It was observed that the UV-photocatalytic property of TiO2-clay nanocomposite (SG) (Egap = 3.17 eV, SBET = 16.58 m2 g−1) for the phenol photodegradation was higher than that of commercial AEROXIDE® TiO2 P25. The activity of SG was greatly improved after silver photodeposition; in fact, the silver-photodeposited into SG highly enhanced the phenol degradation and mineralization efficiencies. The optimization of different experimental parameters, such as the photocatalyst amount, pH, temperature or hydrogen peroxide concentration on the phenol photodegradation under UV irradiation was studied with photodeposited catalyst 1.5%Ag/SG (Egap = 3.12 eV, SBET = 12.16 m2 g−1) based on the response surface methodology selecting composite central design as statistical model. Based on the ANOVA analysis, simulations explained a good fit to the experimental data involving a second-degree polynomial model with a model F-value of 73.31 and coefficient of determination (R2) value of 0.9959. Optimal experimental conditions were found to be a photocatalyst amount of 2 g L−1, solution pH of 5, temperature of 40 °C and hydrogen peroxide concentration of 8 mmol L−1. Under these optimized conditions, total degradation, 91% mineralization and non-toxicity were found, at 50 mg L−1 phenol during 120 min of reaction. Overall, pyrophyllite clay is very attractive as a natural and low-cost mineral for elaborating efficient photocatalysts. [ABSTRACT FROM AUTHOR]

The abnormal corrosion of hot iron ladles was investigated. The performance, the composition and the structure of bricks for hot iron ladles were analyzed. The results show that (1) compared with the alumina-silicon carbide-carbon bricks for the ladle bottom, those for the ladle wall have more pyrophyllite and the AI203 content of 36.32 mass%; their bulk density, apparent porosity and cold compressive strength are lower than the requirement of industry standard; they have poor anti-oxidation performance and are oxidized to form a porous layer during service, which loosens the brick lining structure thus leading to fracture, local wear and structural damage of bricks; (2) without preheating, steel scraps are not completely melted, resulting in slag or steel attachment at the mouth or the bottom of ladles thus increasing damage of ladles; (3) and the residual bricks react with the attached slag to form low melting point phases affecting their hot properties. The refractories for the lining of hot iron ladles must be improved in combination with process changes, not entirely by raw materials replacement to reduce costs. [ABSTRACT FROM AUTHOR]

Pyrophyllite and talc are both tetrahedra–octahedra–tetrahedra (TOT)-type phyllosilicates, but differences can be found in the stacking mode of the layers and the ion occupation. Fourier transform infrared spectroscopy was used to differentiate between pyrophyllite and talc. In the 400–600 cm−1 region, pyrophyllite exhibits six peaks, while talc only exhibits five peaks. In the 1000–1200 cm−1 region, pyrophyllite exhibits three clear peaks at approximately 1051, 1070, and 1121 cm−1; while talc only exhibits one strong peak near 1020 cm−1. The differences between pyrophyllite and talc in the near–infrared (NIR) region are clear in the 4000–4700 cm−1 region, and pyrophyllite exhibits an intense peak around 4615 cm−1, which is attributed to the combination of the OH and Si-O-Si stretching bands. Talc has a maximum peak located near 4324 cm−1, which is attributed to the OH stretching vibration. In addition, talc has a secondary peak near 4366 cm−1. Talc has two other weaker peaks around 4054 and 4180 cm−1. The 7000–7250 cm−1 region exhibits the first fundamental overtone of the OH group stretching vibrations. The common characteristic band of these two minerals is 7175–7183 cm−1. The first overtone of OH stretching vibrations can also be generated by adjacent peaks in the fundamental overtones. The peaks of these two minerals around 7094 cm−1 appear to be a combination of 3630 (±5) cm−1 and 3642 (±3) cm−1.The factor of the first fundamental overtone of the OH group stretching vibration is 1.95 (±0.003). Therefore, the characteristic peaks in the mid-infrared (MIR) and NIR regions can be used to distinguish between pyrophyllite and talc, providing a research basis for further exploration in related geological areas. [ABSTRACT FROM AUTHOR]

The high cost and difficulty in sustainability have hindered the wide application of the general synthetic resins in the controlled-release fertilizers (CRF). Here, the degradable castor oil-based polyurethane (PU) was filled by the natural pyrophyllite (PY) powders, which were pre-modified with few amount (≤0.5 %) of NDZ-201 coupling agent though a simple and economic mechanochemical method. Furthermore, the composite materials of PU and the modified PY (MPY/PU) with enhanced comprehensive properties were prepared and applied in CRF. Moreover, the release behaviors of the coated fertilizers were investigated while tuning the addition amount of modifier or the filling amount of MPY, and it was confirmed that the release performance was highly depended on the hydrophobic and mechanical properties of the composite coating. As a result, the best optimized MPY/PU coating exhibited significantly superior performance to the pure PU materials, and the duration of 80 % nitrogen release was more than 40 days. This confirms that the MPY/PU composite is a promising coating material for the CRF granules.

In recent years, wide-bandgap semiconductor materials such as nano-TiO 2 and nano-ZnO have been extensively utilized in UV protection. However, there are some nonnegligible disadvantages, such as agglomeration and low transparency, which limit their applications. It is urgent to develop new UV shielding materials for UV-radiation protection. In the present study, a new ZnO/pyrophyllite nanocomposite was synthesized by a solid-state reaction method. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence spectrometry (XRF) and UV–vis spectrophotometry. The photocatalytic activity test of the synthesized ZnO/pyrophyllite nanocomposite was also performed to analyse the application prospect of the nanocomposite. The results suggest that the ZnO/pyrophyllite nanocomposite's UV shielding rate is greater than 99% and is superior to that of conventional nano-ZnO. Moreover, the nanocomposite has better transparency than nano-ZnO in the visible light region. The degradation rate of methylene blue by the nanocomposite reached 92.1% after 150 min of UV radiation. The strong photocatalytic activity enables the nanocomposite to be a promising self-cleaning material. These results indicate that the synthesized ZnO/pyrophyllite nanocomposite could be a promising candidate for use in UV-protective and self-cleaning textile finishing industries. [ABSTRACT FROM AUTHOR]

Pyrophyllite (Prl), an aluminosilicate with a balanced mineral structure and extremely small particle size, appears to be an ideal filler but is rarely used in polymers. Herein, a method for the application of pyrophyllite in polymers is reported. A multifunctional filler is prepared by epoxy‐modified pyrophyllite and incorporated into poly(latic acid) (PLA) to enhance its processability and crystallization properties. Results show the effectiveness of epoxy‐modified Prl in composite film with a significant reduction in glass transition temperature, and noteworthy increment in crystallinity and spherulite growth rate. Water vapor barrier properties of PLA composite films increase over 30% with a range of Prl Loading. Furthermore, an enhancement of the tensile strength is increased by 30% and strain at break by 337.1% for PLA composite films compared to neat PLA. This work provides a new idea to prepare the functionalized pyrophyllite fillers and a theoretical basis to develop the application of pyrophyllite for polymers. [ABSTRACT FROM AUTHOR]

The majority of phenol-containing liquid industrial wastes are discharged into natural waters. As a result, several investigations, such as catalytic wet peroxide oxidation (CWPO), have been conducted to remediate these effluents. Copper-supported heterogeneous catalysts were prepared by an impregnation technique and tested in CWPO of phenol. Both the raw pyrophyllite clay and its zeolite form were used as supports. The samples were characterized by BET specific surface area analysis, X-ray diffraction, X-ray fluorescence, and X-ray photoelectron spectra. The effect of temperature (25–70 °C), the concentration of hydrogen peroxide (2–10 mmol·L−1), and the amount of catalyst (0.5–3 g·L−1) were selected for optimization of the catalytic system H2O2-2.5% Cu/ZP using the response surface methodology based on central composite design. The catalyst (2.5% Cu/ZP), with support of synthesized hydroxysodalite zeolite form, showed the best catalytic activity in comparison to that based on raw pyrophyllite support (2.5% Cu/RP). The maximized degradation was 100% after 4 h at optimum conditions (T = 50 °C, [H2O2] = 6.39 mmol·L−1, catalyst amount = 1.82 g·L−1) with 87.73% of mineralization. [ABSTRACT FROM AUTHOR]

The degradation and mineralization of phenol have been studied by means of photocatalysis process using UV light (λmax ≈ 365 nm). The investigated nanocompositephotocatalyst TiO2-Py(750) (SBET=16.58 m2.g− 1), with mixed phases of Anatase and Rutile (52.2/10.7), have been sol-gel synthetized and calcined at 750 °C using a decarbonatedpyrophyllite as layered clay and titanium (IV) t-butoxide, Ti(OCH2CH2CH2CH3)4as precursor. Best results were achieved with TiO2-Py(750), which showed great photo-activity than that of labe-made TiO2 ECT1023t and commercial TiO2AEROXIDE®P25. The influences of different operating parameters, like pH, H2O2 concentration, photocatalyst dose, on the photodegradation of phenol by UV/TiO2-Py(750) system were examined. The TiO2-Py(750) showed total degradation, detoxification and good TOC mineralization at optimum conditions (pH = 5, [H2O2] = 10 mmol.L− 1, m = 2 g.L− 1). The toxicity analysis was carriedout based on the inhibition of bioluminescence of the marine bacteria Vibrio fischeri. The title photocatalysts have been investigated by UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR) and BET specific surface area. [ABSTRACT FROM AUTHOR]

Samples from the pyrophyllite reserves in the Malatya-Pütürge region, used in the production of the whitest cement in Europe, were beneficiated using flotation. The mineralogical composition of the natural pyrophyllite, as determined using X-ray diffraction, includes pyrophyllite, kaolinite, quartz, illite-mica and feldspar. The chemical composition of pyrophyllite contains 69.75% SiO2 and 23.04% Al2O3. The pyrophyllite percentage (40-45 wt.%) of the natural sample increased to 60-80 wt.% after flotation. In flotation experiments, the effects of reagent amounts, types and their mixtures were investigated. Methyl isobutyl carbinol (MIBC) and pine oil as frothers and kerosene as a collector were used in the flotation studies. The use of reagents as mixtures has a positive effect on the beneficiation compared to use on their own. The best result was obtained for a mixture of MIBC with kerosene, which is a non-ionic hydrocarbon oil, yielding a concentrate containing 26.63% Al2O3. Improved results were also observed for kerosene plus frother mixtures after flotation cleaning circuits. The bubbles formed during flotation were photographed and the bubble diameters were measured using the ImageJ program. The Al2O3 content was evaluated by correlating the bubble diameters. In general, selectivity decreased during experiments in which bubble diameters were reduced. [ABSTRACT FROM AUTHOR]

The present work is a review concerning the previous investigations on the vitrification behaviour of clays containing kaolinite, feldspars, muscovite (illite/sericite) and pyrophyllite. These clays are silico-aluminous and have interesting properties as raw materials for structural ceramics. The mineralogical and chemical composition were determined. Then, the vitrification in these clay samples using pressed bodies was investigated by few researchers in the temperature range 800–1350 °C with 0.5–5.5 h of soaking times. The effect of heat treatments on the degree of vitrification in these clays was characterized by bulk densities of the ceramic bodies at the fired stage. It was found some variations of bulk density values for all these clays fired in the range 1000–1150 °C, with marked decreases of the values obtained at 1200 °C and 1300 °C. A first order reaction kinetics was applied to the analysis of vitrification of the ceramic bodies under isothermal heating. The method is based on experimental data of bulk densities, being proposed for the estimation of the relative degree of vitrification resulting from different firing schedules. The analysis considered the temperature dependence of the rate of vitrification following Arrhenius behaviour. Thus, the vitrification activation energy can be obtained. The activation energies for the physical process of vitrification in these clays ranged from 45 to 151 kJ/mol. The relative rates of vitrification or degree of vitrification attained during heating and soaking were calculated. The results suggested that the contribution of vitrification due to heating in all these clays was relatively small compared to the vitrification during soaking. However, it was evidenced that the influence of the particle sizes in the thermal behaviour of these clays cannot be neglected. The vitrification rate equations, as deduced in these previous studies, can be useful tools to estimate the optimum firing conditions of these clays, allowing the extension of this method to other clay types. [ABSTRACT FROM AUTHOR]

Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ~20 and ~130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays. [ABSTRACT FROM AUTHOR]

The efficient removal of Ethidium Bromide (EB), a toxic yet widely used chemical in biochemical industries and laboratories, is crucial to avoid its detrimental effect on human health, aquatic life, and the environment. One effective method is adsorption onto inert surfaces, but the choice of adsorbents is critical for the success of the removal protocols, primarily because of the limitations such as low adsorption capacity, high cost, limited availability, and a lack of understanding of the adsorption mechanism. In this work, Pyrophyllite Nanoclay (PNC), a naturally abundant aluminosilicate is explored as a promising adsorbent for EB. The adsorption process follows the Freundlich isotherm and displays pseudo-second-order kinetics. Under the optimized condition, PNC demonstrates nearly quantitative adsorption of EB and the maximum adsorption efficiency obtained from experiment was 6.53 mg/g (0.017 mmol/g) at room temperature under optimized condition. Through thermodynamic, kinetic analysis coupled with characterization techniques, the mechanism of adsorption is proposed. The adsorbent proves to be reusable, maintaining its performance over three cycles. The utility of the process is further validated and optimized using Response Surface Methodology (RSM). The present work focuses on the performance of PNC as adsorbent and elucidates distinctive surface adsorption mechanism (in comparison to other nanoclays), thus emphasizing the significance of structural, experimental, mechanistic and validation studies in choosing the right adsorbent for the removal toxic chemicals. [Display omitted] • Adsorption of Ethidium bromide on Pyrophyllite nanoclay (PNC) is investigated for the first time. • Kinetic and thermodynamic studies supported by characterization techniques reveal surface adsorption mechanism. • PNC is recyclable for at least three times. • Response Surface Methodology (RSM) optimization is conducted to validate the process. [ABSTRACT FROM AUTHOR]

Phyllosilicate clay minerals have been proposed as a possible buffer material to be used in deep geological repositories containing high-level waste and used nuclear fuel. This work precisely characterizes ion interactions with two types of adsorption sites present in these clays: Mg Al ' substitutions and undercoordinated edge surface atoms. A number of unique structural models were considered to represent the diverse local environments that ions in these systems are likely to encounter. Using molecular dynamics simulation with the CLAYFF potential, the spatial distribution, interlayer composition, and residence times of Na+ and Cl− ions as radionuclide analogs in pyrophyllite and montmorillonite clay models were investigated to identify the most favorable conditions for sequestration. The most significant factor impacting ion adsorption was found to be the localization of charge density at substitution sites. In a montmorillonite system in which substitution sites were distributed evenly to produce a low charge density, sequestration performance was found to be comparable to pyrophyllite. • MD simulation of phyllosilicate edge surfaces in NaCl solution reveal favorable adsorption sites. • Arrangement of Mg Al ' substitution sites can impact interlayer ion content and residence time. • Local charge density is the primary driver in determining adsorption site favorability. • Unhealed edge surfaces promote ion sequestration in the absence of Mg Al ' substitutions. • Evenly distributed Mg Al ' substitutions exhibit low interlayer residence time. [ABSTRACT FROM AUTHOR]

This paper analyzes the extreme application conditions of high temperature, high thermal shock and strong erosion of Al2O3-SiC-C refractories for molten iron ladles. It is considered that the main damage mechanism of the refractories is chemical corrosion of oxides (high contents of CaO, FeO and MnO) in the materials, reaction melting erosion, oxidation or decomposition of C or SiC in the materials, melting erosion at high temperatures, and damage under high thermal shock. The analysis results show that the low carbon and low silica Al2O3-SiC-C materials with high oxidation resistance should be used. The ratio of Al2O3 to SiO2 in the materials should be greater than 2.5, and the andalusite or pyrophyllite with microcracks, Al2O3 or Si3N4 with in-situ particles or fibers, and the clay or metal with ductility at high temperatures should be added to improve the high temperature corrosion resistance and thermal shock resistance. [ABSTRACT FROM AUTHOR]