Silicate Framework Research Articles

Selective Incorporation of Iron Sites into MFI Zeolite Framework by One-Pot Synthesis

Developing highly efficient methods to selectively incorporate active metal sites into the zeolite framework is crucial for the large-scale utilization of metal-zeolites in various catalytic reactions including alkane conversion. Herein, ferrous gluconate is developed as an efficient metal precursor to embed Fe atoms into the MFI siliceous zeolite framework. The crystallization time and Si/Fe ratio are systematically investigated. It is revealed that the ferrous gluconate is well soluble and stable under alkaline conditions, allowing ferrous gluconate to participate in the whole crystallization course of zeolite. Multiple characterizations demonstrate that the tetrahedrally coordinated Fe atoms are selectively incorporated into the MFI siliceous zeolite framework (Fe-MFI). A catalytic test in propane dehydrogenation shows that the optimized Fe-MFI zeolite possesses high activity, propylene selectivity, and durability. This study opens an efficient strategy to incorporate isolated Fe atoms into the zeolite framework.

Fe-doped mesoporous silica catalyzes ascorbic acid oxidation for tumor-specific therapy in scaffold

Ascorbic acid (AA) is a promising antitumor agent, yet its autooxidation is too slow which constrains the further application. Fortunately, the autoxidation process can be accelerated by transition metal catalysts, especially Fe3+ ions. In this study, AA was loaded to Fe-doped mesoporous silica (designated as AA@Fe-SiO2), which was introduced into poly-L-lactic acid (PLLA) and then prepared into a scaffold. Mechanistically, AA@Fe-SiO2 degraded in acidic tumor microenvironment because excessive H+ substituted Fe atoms in the iron silicate framework, releasing Fe3+ and AA. The Fe3+ boosted the pro-oxidation reaction of AA, generating numerous hydrogen peroxide (H2O2) and Fe2+. Then, Fe2+ reacted with H2O2 to initiate Fenton reactions favoring hydroxyl radical generation, triggering oxidative damage on tumor cells to implement tumor-specific therapy. Results showed that the release amount of AA in acidic solution was about 3 times higher than that in neutral solution, which was attributed to the pH-dependency of the degradation of AA@Fe-SiO2 in scaffold. Furthermore, the scaffold generated numerous ascorbate radical intermediate and increased the H2O2 concentration by 120.2%, demonstrating that Fe3+ remarkably accelerated the oxidation rate of AA. Cell experimental results showed that the scaffold caused massive apoptosis of tumor cells, while no obvious cytotoxicity to normal cells, confirming the antitumor specificity of scaffold. This work paves a promising way to construct a biodegradable and catalytic scaffold, featuring effective tumor-specific therapy.

Journey to the centre of the lung. The perspective of a mineralogist on the carcinogenic effects of mineral fibres in the lungs.

This work reviews the bio-chemical mechanisms leading to adverse effects produced when mineral fibres are inhaled and transported in the lungs from the perspective of a mineralogist. The behaviour of three known carcinogenic mineral fibres (crocidolite, chrysotile, and fibrous-asbestiform erionite) during their journey through the upper respiratory tract, the deep respiratory tract and the pleural cavity is discussed. These three fibres have been selected as they are the most socially and economically relevant mineral fibres representative of the classes of chain silicates (amphiboles), layer silicates (serpentine), and framework silicates (zeolites), respectively. Comparison of the behaviour of these fibres is made according to their specific crystal-chemical assemblages and properties. Known biological and subsequent pathologic effects which lead and contribute to carcinogenesis are critically reviewed under the mineralogical perspective and in relation to recent progress in this multidisciplinary field of research. Special attention is given to the understanding of the cause-effect relationships for lung cancer and malignant mesothelioma. Comparison with interstitial pulmonary fibrosis, or "asbestosis", will also be made here.This overview highlights open issues, data gaps, and conflicts in the literature for these topics, especially as regards relative potencies of the three mineral fibres under consideration for lung cancer and mesothelioma. Finally, an attempt is made to identify future research lines suitable for a general comprehensive model of the carcinogenicity of mineral fibres.

Influence of an N,N,N-Trimethyl-1-adamantyl Ammonium (TMAda+) Structure Directing Agent on Al Distributions and Pair Features in Chabazite Zeolite

While organic structure directing agents (OSDAs) are well known to have a directional influence on the topology of a crystallizing zeolite, the relationship between OSDA charge and siting of aliovalent ions on a primarily siliceous framework is unclear. Here, we explore the relationship between OSDA orientation, Al3+ siting, and lattice energy, taking as a model system CHA zeolite occluded with N,N,N-trimethyl-1-adamantyl ammonium (TMAda+) at a Si/Al ratio of 11/1. We use density functional theory calculations to parametrize a fixed-charge classical model describing van der Waals and electrostatic interactions between the framework and OSDA. We enumerate and explore all possible combinations of OSDA orientation and Al location (attending to Löwenstein’s rule) within a 36 T-site supercell. We find that interaction energies vary over 60 kJ/double-six-ring-unit (d6r). Further, analysis of configurations reveals that energies are sensitive to Al–Al proximity, such that low energies are associated with Al3+ pairs in 8-membered rings and higher energies are associated with Al3+ pairs in smaller 6- and 4-membered rings. Comparisons with Al siting inferred from CHA zeolite crystallized with TMAda+ suggest that these computed interaction energies are useful reporters of observed Al siting in CHA synthesized with TMAda+.

U(VI) Coordination Modes in Complex Uranium Silicates: Cs[(UO6)2(UO2)9(Si2O7)F] and Rb2[(PtO4)(UO2)5(Si2O7)

Crystals of two new inorganic uranyl silicates, Cs[(UO6)2(UO2)9(Si2O7)F] (1) and Rb2[(PtO4)(UO2)5(Si2O7)] (2), were produced from melts in evacuated silica tubes. Their structures have been solved by direct methods: 1 is trigonal, P-31c, a = 10.2040(3), c = 17.1278(5) Å, V = 1544.45(10) Å3, R1 = 0.042; 2 is tetragonal, P4/mbm, a = 16.0400(24), c = 3.9231(6) Å, V = 1009.34(10) Å3, R1 = 0.045. 1 is the first example of cation–cation interactions between the uranyl polyhedra in uranyl silicates. Therein, UVI adopts three coordination modes, UO6 octahedra, UO6F, and UO7 pentagonal bipyramids, with the latter sharing common edges to form U2O12 dimers. Three dimers associate into six-membered rings via cation–cation interactions. The structure of 1 can be described as a complex uranyl fluoride silicate framework with channels filled by the U1 atoms and disordered Cs+ cations. 2 represents a new type of topology never observed before among the structures of uranyl compounds; it is also a first complex uranium platinum oxide. Therein, the UO6 tetragonal bipyramids share edges to form chains. Five such chains are stitched into a complex ribbon via the silicon polyhedra. The ribbons are connected into a framework by the PtO4 squares; rubidium atoms are located in the channels of the framework.

Pyrrole-Containing ABA Triblock Brush Polymers as Dual Functional Molecules to Facilely Access Diverse Mesostructured Materials

We report a new type of ABA-type brush-like triblock copolymer (PEGMA-b-PPHMA-b-PEGMA), which is characterized by two hydrophilic end segments (A) and a hydrophobic midblock (B) bearing polymerizable pyrrole moieties. This kind of symmetric triblock copolymers can not only serve as a structure-directing agent for the formation of mesoporous silicates but also function as a polymerizable monomer or carbon source for further chemical conversion to deliver mesostructured polymer or carbon materials within the preformed silicate framework. By utilizing such dual functional macromolecules, rich morphologies of mesostructures are accessible through microphase separation, and the order–order transition among cubic, lamellar, 2D hexagonal, and bicontinuous mesostructures is sensitively achievable by varying the hydrophilic volume fraction of copolymers and TEOS dosage. These features enable facile access to diverse mesostructured silica, polymer, and carbon materials. Remarkably, due to the brush-like polymer architecture and the formation of loop configuration, a widely tunable pore size from mesoscale to macroscale is realizable through using a relatively lower molecular weight copolymer. Importantly, it is found that the brush-like hydrophilic segments of our triblock copolymers can firmly anchor into the silica walls without appreciable escape of copolymer template in commonly used solvents even under reflux extraction, providing a prerequisite for reliable confined chemical transformation into mesostructured polymer and carbon materials. Our work demonstrates that the design and synthesis of functional amphiphilic block copolymers will bring great opportunity for the development of novel mesostructured materials.

Synthesis of [B,Al]-EWT-Type Zeolite and Its Catalytic Properties

EWT zeolite belongs to ultra-large pore zeolite with the 10MR and 21MR channels, which has good thermal stability, certain acid strength and good application prospects in petroleum refining and petrochemical reactions. However, EWT zeolite has fewer medium/strong acid sites, especially Brönsted acid sites, which makes it difficult to apply to acid-catalyzed reactions. The regulation of acid amount and distribution was achieved by boron and aluminum substitution into the siliceous framework of EWT. The physico-chemical properties of the samples were characterized by XRD, SEM, N2 adsorption-desorption, XRF, ICP, Py-IR, NH3-TPD and 11B & 27Al & 29Si MAS NMR. The results show that quantities of boron and aluminum elements can occupy the framework of [B,Al]-EWT to increase the density of medium and strong acid centers, with more acidity and Brönsted acid centers than EWT zeolite. In the reaction of glycerol with cyclohexanone, the conversion of the sample (U-90-08-10/U-90-H-HCl) is significantly higher than that of the EWT sample, approaching or exceeding the Beta zeolite. A catalytic activity study revealed a direct correlation between the Brönsted acidic site concentration and the activity of the catalyst. The U-90-08-10-H catalyst was also considerably stable in the catalytic process. This work shows, for the first time, that extra-large pore zeolites can be used in industrial acid-catalytic conversion processes with excellent catalytic performance.

Characterization of Natural Precious Opal Using Modern Spectroscopic Techniques in Ethiopia: The Case from Delanta, South Wollo

The purpose of this study was to conduct characterization of the Delanta natural opals obtained from different mining sites. Characteristics of opals mined from different geological locality were examined. Six opal samples were collected from the main mining sites found in different localities from Delanta district and characterized using Fourier infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and inductively coupled plasma optical emission spectroscopy characterization techniques. The scanning electron microscope micrographs showed that all the samples have relatively semi-ordered (semi-crystalline) structural surface morphologies composed of tiny spherical particles. The performed X-ray diffraction analysis showed that the samples have main peaks at 20.0°, 21.72°, 36.9°, 44.0°, and 56.85° with 2 θ values between 10° and 60°. The five diffraction peaks are characteristic peak positions of opal-CT. The Fourier infrared spectroscopy data indicated that the prominent absorption bands for cristobalite at 620 and 520 cm−1 were absent from the spectrum. Instead, three bands in the low frequency region centered at 470, 791, and 1100 cm−1 were observed because of the absorptions of the silicate framework (Si-O) vibrations. red−1−1 Moreover,spectra feature of molecular water and silanol (Si-OH) groups with broadabsorption band centered around 3447 cm-1 andthe O-H stretching vibration of watermolecules and water bending vibration withan absorption band centered around 1634 cm-1were observed.. These values were consistently comparable with literature data. The inductively coupled plasma optical emission spectroscopy analysis showed that four main impurities (>500 parts per million) were Ca (∼1,750–4,730 parts per million), Al (∼1,990–4,319 parts per million, K (∼1,670–3,895 parts per million), and Na (∼595–3,723 parts per million). In general, this study revealed that all opal samples taken from six mining sites in Delanta district were found to be opal-CT as per the results of X-ray diffraction and Fourier infrared spectroscopy investigations.

Accurate large-scale simulations of siliceous zeolites by neural network potentials

The computational discovery and design of zeolites is a crucial part of the chemical industry. Finding highly accurate while computational feasible protocol for identification of hypothetical siliceous frameworks that could be targeted experimentally is a great challenge. To tackle this challenge, we trained neural network potentials (NNP) with the SchNet architecture on a structurally diverse database of density functional theory (DFT) data. This database was iteratively extended by active learning to cover not only low-energy equilibrium configurations but also high-energy transition states. We demonstrate that the resulting reactive NNPs retain DFT accuracy for thermodynamic stabilities, vibrational properties, as well as reactive and non-reactive phase transformations. As a showcase, we screened an existing zeolite database and revealed >20k additional hypothetical frameworks in the thermodynamically accessible range of zeolite synthesis. Hence, our NNPs are expected to be essential for future high-throughput studies on the structure and reactivity of siliceous zeolites.

Atomic Insight into the Local Structure and Microenvironment of Isolated Co-Motifs in MFI Zeolite Frameworks for Propane Dehydrogenation.

Embedding metal species into zeolite frameworks can create framework-bond metal sites in a confined microenvironment. The metals sitting in the specific T sites of zeolites and their crystalline surroundings are both committed to the interaction with the reactant, participation in the activation, and transient state achievement during the whole catalytic process. Herein, we construct isolated Co-motifs into purely siliceous MFI zeolite frameworks (Co-MFI) and reveal the location and microenvironment of the isolated Co active center in the MFI zeolite framework particularly beneficial for propane dehydrogenation (PDH). The isolated Co-motif with the distorted tetrahedral structure ({(≡SiO)2Co(HO-Si≡)2}, two Co-O-Si bonds, and two pseudobridging hydroxyls (Co···OH-Si) is located at T1(7) and T3(9) sites of the MFI zeolite. DFT calculations and deuterium-labeling reactions verify that the isolated Co-motif together with the MFI microenvironment collectively promotes the PDH reaction by providing an exclusive microenvironment to preactivate C3H8, polarizing the oxygen in Co-O-Si bonds to accept H* ({(≡SiO)CoHδ- (Hδ+O-Si≡)3}), and a scaffold structure to stabilize the C3H7* intermediate. The Co-motif active center in Co-MFI goes through the dynamic evolutions and restoration in electronic states and coordination states in a continuous and repetitive way, which meets the requirements from the series of elementary steps in the PDH catalytic cycle and fulfills the successful catalysis like enzyme catalysis.

Chemical weathering signatures at Mt. Achernar, Central Transantarctic Mountains II: Surface exposed sediments

Mt Achernar Moraine is a high altitude, high latitude blue ice moraine where typical conditions preclude the presence of liquid water. Cosmogenic and salt accumulation dating indicate that the moraine’s surface is progressively older away from the active ice margin, with surface exposure ages up to 1 Ma. We analyze the chemical and mineralogical transformations in the <63 µm fraction along transects across the moraine. Data include bulk chemical composition, crystalline mineralogy by X-ray diffraction (XRD), and the composition of amorphous or low abundance products of chemical weathering by sequential extraction. These data are analyzed by multiple regression as a function of exposure age and as a function of composition of the moraine’s cobble and pebble-sized clasts. Change with exposure age is defined by the development of salts and carbonate minerals along with the input of detrital material, principally from sedimentary rocks. Clay minerals and amorphous cements breakdown as detrital material in proportions far above their abundance in the rock clasts, whereas framework silicates (i.e. feldspars and quartz) break down in relatively small proportions. Both the carbonate minerals and some of the salts form from atmospheric acids (i.e. H2CO3) that in turn react with other minerals. Mass balance shows that the input of these atmospheric acids balances with gains in authigenic smectites, zeolites, and amorphous material. Many of these minerals also form in the subglacial environment, but are poorly represented in the underlying rock, suggesting a similar chemical weathering regime in both the subglacial and surface environments of this hyper cold and arid setting. The rate of CO2 drawdown into carbonate minerals increases as the moraine progressively thickens, from 3 mg·m2·a−1 in freshly emerging sediments to ∼50 mg·m2·a−1 after 500 ka of exposure. Weathering from acidic aerosols is proportional to atmospheric flux documented in ice cores and does not vary with moraine thickness. The carbonate mineral formation rates are more than an order of magnitude below those of the subglacial environment and as much as two orders of magnitude below those found in warm desert soils. Nevertheless, the drawdown of atmospheric CO2 into carbonate minerals occurs in a terrestrial setting where water exists only in vapor form.

Ion-Pairs in Aluminosilicate-Alkali Synthesis Liquids Determine the Aluminum Content and Topology of Crystallizing Zeolites.

Using hydrated silicate ionic liquids, phase selection and framework silicon-to-aluminum ratio during inorganic zeolite synthesis were studied as a function of batch composition. Consisting of homogeneous single phasic liquids, this synthesis concept allows careful control of crystallization parameters and evaluation of yield and sample homogeneity. Ternary phase diagrams were constructed for syntheses at 90 °C for 1 week. The results reveal a cation-dependent continuous relation between batch stoichiometry and framework aluminum content, valid across the phase boundaries of all different zeolites formed in the system. The framework aluminum content directly correlates to the type of alkali cation and gradually changes with batch alkalinity and dilution. This suggests that the observed zeolites form through a solution-mediated mechanism involving the concerted assembly of soluble cation-oligomer ion pairs. Phase selection is a consequence of the stability for a particular framework at the given aluminum content and alkali type.

Mechanisms of Selected Anionic Dye Removal by Clinoptilolite

The extensive use of color dyes in modern society has resulted in serious concerns of water contamination. Many organic dyes bear charges; thus, materials of opposite charges have been tested for sorptive removal. However, the results from several studies also showed that anionic dyes methyl orange (MO) and alizarin red S (ARS) could be removed from water using minerals of negative charges, but the mechanisms were not addressed. In this study, negatively charged clinoptilolite was tested for its removal of anionic dyes MO and ARS from water under different physico-chemical conditions and to investigate the mechanism of Mo and ARS removal. The sorption capacities were 166 and 92 mmol/kg for MO and ARS, respectively, confirming the uptake of anionic dyes on negatively charged framework silicates. The influence of solution pH and ionic strength on MO removal was minimal, indicating the strong affinity of anionic dyes for clinoptilolite in comparison to other inorganic species. It was speculated that the N in the dimethyl group may bear a partial positive charge, which may have a net electrostatic attraction to the negatively charged mineral surfaces for MO sorption. For ARS, sorption may involve hydrogen bonding formation between the dye and the clinoptilolite. Moreover, under the experimental conditions, the MO molecules form dimers in solution via dimeric π-π interactions. Thus, the sorption of the dimers or aggregation of the MO monomers and dimers on clinoptilolite surface was attributed to additional MO removal, as suggested by molecular dynamic simulations. The speculation was supported by FTIR analyses and molecular dynamic simulations. As such, negatively charged Earth materials may be used as sorbents for the removal of certain anionic dyes via sorption, a new perspective for the innovative use of Earth materials.

Nitrogen Retention in Feldspar: Implications for Nitrogen Transport in Subduction Zones

AbstractNitrogen recycling between Earth's interior and exterior determines the evolution of the atmosphere and habitability of the planet. However, the contribution of subduction to the deep nitrogen recycling is still highly debated. Ammonium‐bearing silicate minerals are the main nitrogen carriers in subduction zones. Nitrogen retention in subduction‐zone minerals determines the subducted nitrogen fluxes to the deep Earth. Here, we reveal ammonium behavior in a natural ammonium‐bearing feldspar at elevated temperatures to 1000°C and pressures to 19.99 GPa. With increasing temperature and pressure, ammonium interacts with the silicate framework and forms hydrogen bonding. The ammonium loss rates are on the order of 10−15, 10−14, and 10−13 at 800, 900, and 1000°C, respectively, with activation energy of 271 ± 13 kJ/mol. The activation energy of ammonium loss in feldspar is higher than that in phengite. Moreover, the ammonium diffusivities are similar to that of hydrogen in feldspar, but much slower than that of molecular water and faster than those of K and Ar. The results imply that most of nitrogen can be potentially retain in the feldspar structure before feldspar breakdown. Considering that feldspar could be stable to a great depth along cold subduction, it could be a potential carrier for nitrogen transport to the deep Earth.

Differences in Catalytic Activity and Durability of Nitrogen Sites on Nitrided SBA-15 or Porous Carbon Nitride

Nitrided SBA-15 (NSBA-15) is a solid base catalyst for several reactions, in which the basicity arises from a lone pair on a nitrogen atom substituted in the silicate framework. Porous carbon nitride (PCN) formed on a SBA-15 template is also a solid base catalyst with a nitrogen atom as the active site. In this study, the catalytic activity and durability of nitrogen atoms in nitrided mesoporous silica and porous carbon nitride were compared to evaluate the origin of basicity by using the Knoevenagel condensation of benzaldehyde with active methylene compounds. With malononitrile (pKa of 11.1) as the methylene compound, both NSBA-15 and PCN showed a high product yield. Using ethyl cyanoacetate (pKa of 13.1), only NSBA-15 catalyzed the reaction, probably because the active site of NSBA-15 is a quasi-aliphatic amine and that of PCN is an aromatic amine. On the other hand, PCN showed high durability as the content of nitrogen was not decreased by the catalytic reaction and long-term storage, whereas the Si–N bond in NSBA-15 easily underwent hydrolysis.

Silicate minerals - Potential source of potash - A review

The third crucial macronutrient required for the development and growth of plants in addition to nitrogen and phosphorous is potassium. The quantity of soluble potassium in soil that could be directly taken up by plants is less and present in the form of evaporite deposits situated in countries lying in the Northern hemisphere such as Canada, Belarus, Israel, USA and Russia. All other countries are dependent on imports from these countries to fulfil their potash requirement. But a major part of potassium exists in insoluble form as silicate minerals abundantly in these countries which can compensate for the potassium deficit. Mostly feldspar and feldspathoid from the tectosilicate group and micaceous minerals from the phyllosilicate group are the common potassium bearing silicates containing 5–15% K2O. Tectosilicates are framework silicates in which potassium is present in the three-dimensional silicate tetrahedra. Phyllosilicates are sheet silicates having a two-dimensional parallel sheet structure and potassium ions are located in the interlayers of the silicate structure. Various processes have been adopted to release the potassium from these silicate resources such as bio-leaching using various algal, bacterial and yeast strains, acid leaching with different acids of varying concentrations, base leaching with diverse strategies and roast-leach studies with alkali and alkaline salts to optimise the recovery. This review summarizes versatile methodologies that have been approached and the scope of various works that could be further accomplished.

Prediction of Thermal Properties of Zeolites through Machine Learning

The use of machine learning for the prediction of physical and chemical properties of crystals based on their structure alone is currently an area of intense research in computational materials science. In this work, we studied the possibility of using machine-learning-trained algorithms in order to calculate the thermal properties of siliceous zeolite frameworks. We used as training data the thermal properties of 120 zeolites, calculated at the DFT level, in the quasi-harmonic approximation. We compared the statistical accuracy of trained models (based on the gradient-boosting regression technique) using different types of descriptors, including ad hoc geometrical features, topology, pore space, and general geometric descriptors. While geometric descriptors were found to perform best, we also identified limitations on the accuracy of the predictions, especially for a small group of materials with very highly negative thermal expansion coefficients. We then studied the generalizability of the technique, demonstrating that the predictions were not sensitive to the refinement of framework structures at a high level of theory. Therefore, the models are suitable for the exploration and screening of large-scale databases of hypothetical frameworks, which we illustrate on the PCOD2 database of zeolites containing around 600 000 hypothetical structures.

Development of Flame Retardant Property on Sodium Silicate Treated Paper Based Materials

The preparation of cellulose-based flame retardant paper treated with sodium silicate and silicon dioxide (SiO2) colloidal particle by simple immersion process is reported. Cellulose-based paper was preheated at 90°C for surface preparation. The heat treated paper was immersed in solution of sodium silicate-SiO2 at different immersion time ranging from 15 min to 24 hrs. Treated solution diffused into paper coated on the paper fiber and filled the void in the paper microstructure. Treated paper was heated at 90°C to convert an impregnated sodium silicate-SiO2 precursor into silicate framework. The treated paper showed Vsym Si-O-Si from siloxane bond at 792 cm-1 which confirmed a presence of SiO2 in paper. Treated paper at 1 hr immersion showed the highest weight percent gain (WPG) of 40% and total combustion time was improved to 14 sec.

Crystal structures and X-ray powder diffraction data for Cs2NiSi5O12, RbGaSi2O6, and CsGaSi2O6 synthetic leucite analogues

Leucites are tetrahedrally coordinated silicate framework structures with some of the silicon framework cations partially replaced by divalent or trivalent cations. These structures have general formulae A2BSi5O12 and ACSi2O6; where A is a monovalent alkali metal cation, B is a divalent cation, and C is a trivalent cation. In this paper, we report the Rietveld refinements of three more synthetic leucite analogues with stoichiometries of Cs2NiSi5O12, RbGaSi2O6, and CsGaSi2O6. Cs2NiSi5O12 is Ia$\bar{3}$d cubic and is isostructural with Cs2CuSi5O12. RbGaSi2O6 is I41/a tetragonal and is isostructural with KGaSi2O6. CsGaSi2O6 is $I\bar{4}3d$ cubic and is isostructural with RbBSi2O6.

Preparation of continuous silicate fiber from pyroxene and K-feldspar mixture

Mixtures of pyroxene and K-feldspar instead of basalt rock were adopted to study the formation of continuous basalt fiber. Changing in mass ratio of the two minerals simulated acidic to ultrabasic igneous rocks. Within a specific composition range, continuous fiber was successfully prepared, whose fibration property was governed by both the viscosity and depolymerization degree (NBO/T) of the silicate melts. FT-IR and Raman spectra provided detailed structural information on the correlations between fibration property and the connection of silicate framework units. A proper ratio and arrangement of Q2 ([Si2O6]4−) and Q3 ([Si2O7]6−) was considered a key factor influencing the formation and tensile strength of the fiber. The results in present work also sheds light on a new route to prepare analogous basalt fiber by a proper combination of different industrial or mining silicates instead of exploiting new basalt rocks.