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• Natural ultramarine blue pigment (Lapis Lazuli or Lazurite) photo-catalytically degrades a linseed oil binder, similarly to the effects of synthetic ultramarine blue. • Sodalite pigment also acts as a photo-catalyst, despite the absence of enclathrated polysulfur radical anions. • The zeolitic aluminosilicate cage structure, present in ultramarine blue as well as Sodalite, and not the enclathrated sulfur species are responsible for the photo-catalytic effect. • Relatively stable synthetic binders are less affected by the presence of ultramarine blue. Photo-catalytic degradation of a linseed oil binder by natural ultramarine (Lapis Lazuli or Lazurite) and Sodalite in paint layers was studied. Both pigments degrade the binder under xenon arc exposure, leading to erosion of the binder at the surface, increased roughness, light scattering and desaturation of the color. Both pigments behave similarly to synthetic ultramarine blue studied earlier. The results for Sodalite provide further proof that the zeolitic nature of the aluminosilicate cage causes the catalytic degradation and that the enclathrated polysulfur radical anions S 2 -. and S 3 -. trapped inside the cage are not responsible for the catalytic action. Relatively stable synthetic binders are less affected by the presence of synthetic ultramarine blue. The paints were aged in a xenon arc apparatus using a simulated indoor environment (radiation > ca. 320 nm). The samples were analyzed using diffuse reflectance spectroscopy in the UV–vis and short wavelength infrared (SWIR) ranges, Raman spectroscopy, field-emission gun scanning electron microscopy (FEG-SEM) and FTIR. [ABSTRACT FROM AUTHOR]

The sonohydrothermal (SHT) treatment is an innovative technique allowing the simultaneous coupling of low frequency ultrasound and hydrothermal conditions for the synthesis of materials. The aim of the present work was to investigate, for the first time, the synthesis of zeolite A and its formation mechanism under SHT conditions. The zeolite synthesis was carried out under sonohydrothermal conditions using a specially designed reactor that allows the application of ultrasonic irradiation at 20 kHz in an autoclave-type reactor heated up to 200 °C under autogenous pressure. The conversion kinetics of the amorphous hydrogel to zeolite A and its further conversion to sodalite were studied. Syntheses were performed in the SHT reactor at 80 and 100 °C, varying the synthesis time from 15 minutes to several hours. The required time to obtain fully crystalline zeolite A under sonohydrothermal conditions was only 25 minutes, highlighting a significantly improved crystallization rate compared to silent conditions (a 9.6-fold kinetic gain). In addition, the resulting zeolite A has smaller particles and a more homogeneous particle size distribution than the zeolite synthesized by hydrothermal treatment. These results can be explained by the sonofragmentation of the amorphous gel and the concomitant enhanced mass transfer of the building units at the interface between the crystallite surface and the solution resulting from the acoustic cavitation activity under SHT conditions. Compared to classical hydrothermal heating, a drastic kinetic increase of the transformation of zeolite A into the more stable sodalite phase was also observed under sonohydrothermal conditions. [ABSTRACT FROM AUTHOR]

In this work, a meso-macroporous analcime/sodalite zeolite composite was produced by a hybrid synthesis process between a complex template method and hydrothermal treatment at 220 °C of naturally abundant kaolinitic-rich clay, using dodecyltrimethylammonium bromide as an organic soft template to enhance the mesoporous structure. The chemical and morphological properties of the developed zeolites composite were characterized using powder X-ray diffraction (PXRD), attenuated total Reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), N2 adsorption/desorption; and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) methods were used to study the morphology, chemical composition and structure of the product. Two types of zeolite particles were obtained:(1) hollow microsphere with an attached analcime icositetrahedron of 30–40 µm in size and (2) sodalite microsphere with a ball-like morphology of 3–4 µm in size. Both N2 adsorption/desorption and surface area data confirmed the high potentiality of the produced zeolite composite to act as an excellent adsorbent to remove inorganic pollutants such as Cu, Cd, Cr, Ni, Zn, and Pb ions, organic pollutants such as dyes, phenolic compounds, and surfactants from water; and their high catalytic activity, especially in the oxidation reaction of volatile organic compounds. The catalytic activity and adsorption ability of the produced analcime/sodalite composite will be tested experimentally in future work. [ABSTRACT FROM AUTHOR]

The formation of the solid phases CaS, 3CaO.SiO2 and CaO.Al2O3 around the lime particle decreases the efficiency of desulfurization by the kanbara reactor (KR) process. The addition of fluxes reduces the formation of these phases. The addition of Al and Si can also have this effect, depending on the added levels. In this study, different mixtures based on CaO with different levels of fluorspar, sodalite (Nepheline Syenite), and SiO2 and Al2O3 content were studied and used in the desulfurization process of hot metal. These mixtures were added to a bath of liquid hot metal at 1400 °C. All experiments were performed with mechanical agitation. Samples were taken at times of 5, 10, 15, and 20 min, and analyses were performed to evaluate the variation of sulfur over time. The Thermo‐Calc software was used to determine the formed phases, solid fraction, and liquid fraction of the different mixtures. With this data, different values of the Global Desulfurization Factor (FGDeS) were calculated, which was developed to evaluate and predict the efficiency of hot metal desulfurizing mixtures by the KR process. The results of showed that fluorspar was more efficient than sodalite. The FGDeS had a correlation factor (R2) above 0.9 with the desulfurization efficiency. [ABSTRACT FROM AUTHOR]

This review contains data on a wide class of microporous materials with frameworks belonging to the sodalite topological type. Various methods for the synthesis of these materials, their structural and crystal chemical features, as well as physical and chemical properties are discussed. Specific properties of sodalite-related materials make it possible to consider they as thermally stable ionic conductors, catalysts and catalyst carriers, sorbents, ion exchangers for water purification, matrices for the immobilization of radionuclides and heavy metals, hydrogen and methane storage, and stabilization of chromophores and phosphors. It has been shown that the diversity of properties of sodalite-type materials is associated with the chemical diversity of their frameworks and extra-framework components, as well as with the high elasticity of the framework. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis of magnetic zeolite A using fly ash as the main sources of SiO₂ and Al₂O₃, by hydrothermal use in the adsorption of Pb2, Cd2, Zn2⁺ and Cu2. The composite synthesis was successful, and the obtained material was characterised by using different techniques, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), Infrared vibrational spectroscopy (FTIR), Electron Microscopy (SEM), and pH point of zero charge (pHpzc). XRD measurements confirm zeolites A as the main crystalline phases (98.5%), with the presence of a small amount of sodalite (1.5%). In the SEM of magnetic composite, the characteristic morphology for zeolite A was noted, with magnetite nanoparticles dispersed on its surface, resulting in a composite with magnetic properties. In the adsorption study, the magnetic composite showed a fast rate of adsorption, in which the pseudo second order model was the one that best described the experimental data of the metal ions under study. The Redlich-Peterson isotherm model best represented the experimental data of Pb2⁺ and Cd2⁺, while the Langmuir and Sips models fitted Zn2⁺ and Cu2⁺, respectively. Thus, the results showed that the magnetic composite presented high magnetic quality, facilitating its separation from the aqueous medium, as well as being a promising adsorbent in the adsorption of metal ions in aqueous medium. [ABSTRACT FROM AUTHOR]

The corundum-mullite bricks used in the combustion zone of a hazardous waste incineration rotary kiln were sampled,and the microstructure and composition of the sampled residual bricks were analyzed by XRD,SEM,and EDS.The corrosion mechanism of corundum mullite bricks under the corrosion of halogen-containing and high sodium salt content slag in hazardous waste incineration rotary kilns was investigated.The results demonstrate that the sodium salt,potassium salt,Br,Cl,and other elements in the slag possess strong corrosion and penetration abilities,generating low melting point and low density substances such as NaCl,KBr,and sodalite in the matrix,which decreases the hot performance of the brick in the combustion zone and accelerates the corrosion and wear of the brick.On the other hand,they cause irreversible volume expansion of the brick body,leading to spalling during the operation of the rotary kiln. [ABSTRACT FROM AUTHOR]

An unreported rhenium-based calcium aluminum sodalite (CARe sodalite) has been synthesized by a traditional solid-state method. The rhenium is located in the sodalite β-cage and can be reduced under 5% H2 forming gas without breaking the cage framework. Preliminary characterizations of the structural, optical, and magnetic properties are reported. [ABSTRACT FROM AUTHOR]

Alum sludge (AS) from water treatment plants is an abundant, non-toxic residue with high Si and Al contents. These characteristics make it an ideal precursor for zeolite synthesis, not only reducing the environmental impacts from AS disposal but also adding value to the waste by promoting its reuse. Herein, we propose a route to prepare zeolitic materials from AS, aiming for its application as a component of slow-release fertilizers, using mild conditions and cost-effective hydrothermal synthesis. X-Ray Diffraction revealed the formation of sodalite (Na-SOD) in short times (5-10 h) and moderate temperatures (100-120ºC), with sodium silicate addition favoring Si-quartz consumption and zeolite crystallization, without a fusion step. The Na-SOD showed a desirable cation exchange capacity, reaching 117 mg g-1 for K+. A K-SOD fertilizer was then prepared with an average 490 nm size, 2 m2 g-1 BET surface area, and slow-release behavior. Incubation in soil confirmed that Al was inactive in K-SOD and did not immobilize phosphate, in addition to promoting high K+ availability. The results support the potential of AS reuse for application in agriculture as an efficient and sustainable fertilizer.

We employ all-atom well-tempered metadynamics simulations to study the mechanistic details of both the early stages of nucleation and crystal decomposition for the benchmark metal–organic framework (MOF) ZIF-8. To do so, we developed and validated a force field that reliably models the modes of coordination bonds via a Morse potential functional form and employs cationic and anionic dummy atoms to capture coordination symmetry. We also explored a set of physically relevant collective variables and carefully selected an appropriate subset for our problem at hand. After a rapid increase of the Zn–N connectivity, we observe the evaporation of small clusters in favor of a few large clusters, which leads to the formation of an amorphous highly connected aggregate. Zn (MIm) 4 2 − and Zn (MIm) 3 − complexes are observed with lifetimes in the order of a few picoseconds, while larger structures, such as four-, five-, and six-membered rings, have substantially longer lifetimes of a few nanoseconds. The free ligands act as "templating agents" for the formation of sodalite cages. ZIF-8 crystal decomposition results in the formation of a vitreous phase. Our findings contribute to a fundamental understanding of MOF's synthesis that paves the way to controlling synthesis products. Furthermore, our developed force field and methodology can be applied to model solution processes that require coordination bond reactivity for other ZIFs besides ZIF-8. [ABSTRACT FROM AUTHOR]

Alkali metal clusters with a single unpaired s-electron can be arranged three-dimensionally in a sodalite crystal by loading the guest alkali atoms. Na, K, and K-Rb alloy clusters are known to be Mott insulators and to exhibit antiferromagnetic ordering. The Néel temperature increases from about 50 K to about 100 K in this order. In this study, Li-Na alloy, Na-K alloy, and pure Rb samples were newly prepared and their magnetic, electrical conductivity, and optical properties were investigated, including those of previous samples. The Na-K alloy samples showed antiferromagnetic properties, which were intermediate between those of the Na and K samples. However, the Rb sample showed a non-magnetic metallic state. The shallower ionization potential in Rb is thought to cause an insulator-metal transition (Mott transition) due to weaker on-site Coulomb repulsion between electrons and larger electron transfer energy between neighboring clusters. On the other hand, the Li-Na alloy sample showed a non-magnetic insulating state. It is thought that the two electrons form a spin-singlet pair due to the strong electron-lattice interaction. In terms of electron correlations and polaron effects, the full picture of the element species dependence of the alkali metal-loaded sodalite is reviewed. [ABSTRACT FROM AUTHOR]

Microporous materials containing hydrated silanol groups Si–OH as well as hydrated proton complexes, H2n+1On+, including hydronium (n = 1), Zundel (n = 2), and Eigen (n = 4) cations, are of practical importance as potential ion exchangers and ion conductors. In this paper, we provide data on crystal‐chemical features, hydrogen bonding and Raman spectra of alkaline microporous titano‐, niobo‐, zircono‐, and aluminosilicate minerals belonging to the labuntsovite, lovozerite, eudialyte, and sodalite groups in which a part of sodium was substituted by hydrated proton complexes under low‐temperature hydrothermal or supergene conditions. Most minerals studied in this work do not have synthetic analogues and are considered as possible natural prototypes of microporous materials with technologically important properties. The obtained experimental data and their comparison with the results of ab initio theoretical calculations published elsewhere show that Raman spectroscopy is an effective tool for the precise identification of hydrated proton complexes with extremely strong hydrogen bonds and estimation of corresponding O···O distances in the range of 2.37–2.68 Å. The presence of hydrated proton complexes in microporous silicates is a clear and sensitive geological indicator showing that a rock underwent the low‐temperature alteration. [ABSTRACT FROM AUTHOR]

Sodalite crystals were prepared with varying hydrogel Al2O3/SiO2 molar ratio at room temperature via hydrothermal method. The particulate properties of products prepared under room temperature and elevated temperature condition were compared. The results displayed that spherical particles built of small crystallites were obtained after 10 h of room-temperature hydrothermal treatment; while with the same gel composition, the sodalite obtained for 10 h at 90 oC was large lepispherical particles. Moreover, the samples prepared at room temperature exhibited much higher Cd2+ sorption capacities, and the maximum adsorption capacities of Cd2+ were tested to be 84.2, 88.6, 92.9, and 98.2 mg/g for the sodalite synthesized with hydrogel Al2O3/SiO2 molar ratios of 0.43, 0.55, 0.68 and 0.84, respectively. The reasons can be due to its specific porous structure, large surface area, and more adsorption active sites. Additionally, the kinetics and isotherm analysis revealed that pseudo-second order model and Langmuir model agreed well with the adsorption processes. This work offered an economic synthesis method of sodalite to achieve efficient Cd2+ removal from aqueous solution. [ABSTRACT FROM AUTHOR]

The search for a sustainable society makes necessary the reuse of residues contributing to the producing high-value product. Producing new materials with high-added value increases technological development and builds up new applications. The present study aimed to use residue from the alumina industry and coal ash generated in thermal plants in energy production to synthesize zeolite for wastewater treatment to remove Cs and Pb. Two types of nanomaterials were synthesized: zeolite 4A (ZEA) and zeolite sodalite (ZSD). The Cs adsorption efficiency achieved 73% and 9.4% for ZEA and ZSD, respectively, fitting better for Lineweaver-Burk isotherm and both zeolites removed 100% of Pb from synthetic solutions. Results here reported may be used to design novel wastewater treatment systems from nuclear plants and other industrial processes. The present study can contribute to achieving Sustainable Development Goals 9, 11, and 12. Cs removal achieved 73% for ZEA fitting better for Lineweaver-Burk isotherm Nanozeolites were obtained from alumina industry residue Nanomaterials were capable to remove elements present in nuclear wastewater Removal of Pb achieved 100% by both zeolites [ABSTRACT FROM AUTHOR]

We report on the primary and secondary mineralogies of three coarse‐grained igneous calcium‐aluminum‐rich inclusions (CAIs) (Compact Type A [CTA], Type B [B], and forsterite‐bearing type B [FoB]) from the Northwest Africa (NWA) 5343 (CK3.7) and NWA 4964 (CK3.8) carbonaceous chondrites, compare them with the mineralogy of igneous CAIs from the Allende (CV3.6) chondrite, and discuss the nature of the alteration processes that affected the CK and CV CAIs. The primary mineralogy and mineral chemistry of the CK3 CAIs studied are similar to those from Allende; however, primary melilite and anorthite are nearly completely absent. Although the secondary minerals identified in CK CAIs (Al‐diopside, andradite, Cl‐apatite, clintonite, forsterite, ferroan olivine, Fe,Ni‐sulfides, grossular, ilmenite, magnetite, plagioclase, spinel, titanite, and wadalite) occur also in the Allende CAIs, there are several important differences: (i) In addition to melilite and anorthite, which are nearly completely replaced by secondary minerals, the alteration of CK CAIs also affected high‐Ti pyroxenes (fassaite and grossmanite) characterized by high Ti3+/Ti4+ ratio and spinel. These pyroxenes are corroded and crosscut by veins of Fe‐ and Ti‐bearing grossular, Fe‐bearing Al,Ti‐diopside, titanite, and ilmenite. Spinel is corroded by Fe‐bearing Al‐diopside and grossular. (ii) The secondary mineral assemblages of grossular + monticellite and grossular + wollastonite, commonly observed in the Allende CAIs, are absent; the Fe‐bearing grossular + Fe‐bearing Al‐diopside ± Fe,Mg‐spinel, Fe‐bearing grossular + Fe,Mg‐olivine ± Fe,Mg‐spinel, and Ca,Na‐plagioclase + Fe‐bearing Al‐diopside + Fe‐bearing grossular assemblages are present instead. These mineral assemblages are often crosscut by veins of Fe‐bearing Al‐diopside, Fe,Mg‐olivine, Fe,Mg‐spinel, and Ca,Na‐plagioclase. The coarse‐grained secondary grossular and Al‐diopside often show multilayered chemical zoning with distinct compositional boundaries between the layers; the abundances of Fe and Ti typically increase toward the grain edges. (iv) Sodium‐rich secondary minerals, nepheline and sodalite, commonly observed in the peripheral portions of the Allende CAIs, are absent; Ca,Na‐plagioclase is present instead. We conclude that coarse‐grained igneous CAIs from CK3.7–3.8 s and Allende experienced an open‐system multistage metasomatic alteration in the presence of an aqueous solution–infiltration metasomatism. This process resulted in localized mobilization of all major rock‐forming elements: Si, Ca, Al, Ti, Mg, Fe, Mn, Na, K, and Cl. The metasomatic alteration of CK CAIs is more advanced and occurred under higher temperature and higher oxygen fugacity than that of the Allende CAIs. [ABSTRACT FROM AUTHOR]

Coal fly ash (CFA) is an excellent source of silica–alumina precursor that can be used for the copious and continuous manufacturing of zeolitic materials. This study provides a novel strategy to prepare zeolitic sodalite from CFA as adsorbents for Congo red (CR) dye removal under variable conditions. Sodalite crystals (S) were prepared by a calcination of sodium–aluminum silicate derived from CFA in either absence or presence of cetyltrimethylammonium bromide (CTAB) surfactant (CTAB-S). SEM, XRD, FTIR, and N2 adsorption measurements were demonstrated. XRD results confirmed the presence of mullite and quartz as main components in CFA which converted to sodalite phases after calcination in existence of CTAB. SEM revealed that agglomerated larger particles were formed in S sample without adding CTAB, whereas smaller spherical particles aggregated together upon adding CTAB to form zeolitic structure (CTAB-S). FTIR showed the characteristic absorption bands of sodalite related to oxygen-containing Si and Al groups. Batch adsorption isotherm studies were conducted to evaluate the maximum adsorption capacities of S and CTAB-S, which were amounted to be 152.7 and 184.8 mg/g, respectively. Adsorption of CR dye was fitted with Freundlich isotherm. Kinetic results perfectly matched with pseudo-second-order model and intraparticle diffusion. Thermodynamic findings indicated that the adsorption of CR dye over both samples was endothermic and spontaneous in nature. CTAB-S sample showed the best reusable adsorbent, according to reuse experiments employing water as a desorbing agent. Overall, it can be concluded that CFA-derived sodalite can be used as an effective adsorbent for anionic dyes removal from wastewater. [ABSTRACT FROM AUTHOR]

The present work is part of a systematic mineralogical and petrographic characterization of mica-bearing xenoliths from Somma-Vesuvius volcano (Roman Magmatic Province, southern Italy). Skarns, composite skarns-marbles and cumulates from Pompeii Plinian eruption (AD 79), and skarns and syenite from Avellino eruption (3945 ± 10 cal yr BP) were investigated to define the crystal chemistry of the Somma-Vesuvius trioctahedral micas and to draw inferences on petrogenetic processes to which they were subjected. Xenoliths were characterized by means of polarized optical microscopy, scanning electron microscopy (SEM-EDS), X-ray powder diffraction (XRPD), and bulk-rock geochemical analyses. Mica crystals were studied using electron microprobe analysis (EMPA) and single-crystal X-ray diffraction (SCXRD). Micas from skarns are variably associated with Mg ± Ca silicates (clinopyroxene, vesuvianite, humite, clinohumite, chondrodite, forsterite, and garnet), other sporadic silicates (anorthite, sodalite, titanite, and britholite), apatite, calcite, various types of oxides, as well as rare sulfides and halides. In composite skarn-marble rocks, the mineral assemblages show some differences compared to skarns, as a lack of clinopyroxene and the presence of dolomite. Cumulate samples consist of mica and clinopyroxene, whereas syenite is mainly composed of mica, K-feldspar, feldspathoids, and clinopyroxene. Together with mica, apatite occurs in all the lithotypes. Trace element arrays are scattered for skarn and composite skarn-marble samples. The REE patterns have a general enrichment in light (La, Ce, Pr, Nd) and medium (Sm, Eu, Gd, Tb, Dy) rare earth elements, in some cases with slight positive Gd anomaly. Cumulate samples generally have low amounts of Ba, Sr, Zr, and Th, while syenite exhibits low concentrations of trace elements, except for Rb, Cs, and Tl. Mica crystals occurring in the studied xenoliths are phlogopite with different Al and Mg contents at the octahedral site, a negligible tetraferriphlogopite component and variable dehydrogenation degree. All samples belong to the 1M polytype (C2/m and C2 space group) and have a wide range of unit-cell parameters, especially of the c axis [5.3055(1) ≤ a ≤ 5.3218(1) Å, 9.1893(1) ≤ b ≤ 9.2188(4) Å, 10.1803(2) ≤ c ≤ 10.2951(2) Å]. The shortest c-cell parameter pertains to de-hydrogenated phlogopite from Avellino skarn, whereas OH-rich phlogopite from Pompeii composite skarns-marbles has a c-cell parameter that approximates that of the end-member phlogopite. Overall, it is observed that the crystal chemistry of the micas studied here extends the known range of the other Vesuvian micas from the literature. The Ti-depletion and the wide degree of dehydrogenation of phlogopites from skarns and composite skarns-marbles suggest that the studied samples originated under variable pressure conditions. In addition, the presence of humite in the mineral assemblage seems to indicate the occurrence of devolatilization reactions. The scarce mica occurrence in cumulate and mainly in syenite, instead, may depend on pressure conditions in the magma storage system exceeding the mica stability. [ABSTRACT FROM AUTHOR]

The efficiency of the vapor phase crystallization (VPC) process in zeolite formation using mixtures of a natural source (obsidian) and common waste materials (red mud and fly ash) was analyzed. The aim was to demonstrate that water molecules available during this treatment control mainly the synthesis of sodalite, regardless of the raw material used, as long as it is rich in amorphous silica and alumina pre-fused with NaOH. The data indicate that increasing the temperature to generate steam from distilled water during the VPC process results in the continuous transformation of amorphous material into sodalite and, subordinately, cancrinite. The formation of the newly formed phases was monitored by powder XRD and SEM. [ABSTRACT FROM AUTHOR]

The utilization of lithium slag (LS), a solid waste generated during the production of lithium carbonate, poses challenges due to its high sulfur content. This study presents a novel approach to enhancing the value of LS by employing alkali fusion and hydrothermal synthesis techniques to produce zeolite A at low temperatures. The synthesis of high-purity and crystalline lithium-slag-based zeolite A (LSZ) at 60 °C is reported for the first time in this research. The phase, morphology, particle size, and structure of LSZ were characterized by XRD, SEM, TEM, N2 adsorption, and UV Raman spectroscopy, respectively. High-purity and crystalline zeolite A was successfully obtained under hydrothermal conditions of 60 °C, an NaOH concentration of 2.0 mol/L, and a hydrothermal time of 8 h. The samples synthesized at 60 °C exhibited better controllability and almost no byproduct of sodalite occurred compared to zeolite A synthesized at room temperature or conventional temperature (approximately 90 °C). Additionally, the growth mechanism of LSZ was elucidated, challenging the traditional understanding of utilization of lithium and enabling the synthesis of various zeolites at lower temperatures. [ABSTRACT FROM AUTHOR]

A new type of geopolymer with an iron–oxygen–silicon linkage is synthesized and reported for the first time. The aim was to enable the iron-rich clay material (laterite) as a raw material for the geopolymerization. Iron was used in different ratios ranging 1–3 wt. % in the raw mix designing geopolymer followed by activation with concentrated alkali solutions of NaOH and KOH in different concentrations. The bonding of Fe–O–Si was confirmed from the FTIR peaks in NaOH- and KOH-based geopolymers. X-ray diffraction studies confirmed the formation of zeolitic, sodalite, and almandite phases. The final product has shown a compressive strength of 2371.8 and 1503 kN/m2 and can be used as a construction material. [ABSTRACT FROM AUTHOR]

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In the eruptive event of Tajogaite (2021) in La Palma, Canary Islands, large quantities of volcanic ash were accumulated, affecting the local environment and urban areas. In this study, volcanic ash sampled from urban areas (catalogued as municipal waste (20 03 03) by the European Wastes Catalogue) were converted into zeolites by hydrothermal synthesis at 100 °C with previous alkaline fusion at 550 °C with distilled water. During this process, new phases of zeolite principally type X and sodalite have been identified by XRD at 2 h of incubation. These zeolites, with the course of incubation time, present competitive processes where the transformation into sodalite develops after 24 h as the predominant phase. The synthesized zeolitic material presents a high concentration as impurities in Fe2O3 (13.70 wt%), Na2O (12.70 wt%), CaO (11.65 wt%), and TiO2 (3.89 wt%) coming from the volcanic ash and NaOH introduced in the synthesis methodology. These impurities impart different physicochemical capabilities to the zeolitic material. The application of zeolites obtained in a preliminary fluoride adsorption experiment with volcanic leachate water rich in fluoride has been tested in a novel way. Removal efficiencies of 41.4% at acidic pH (5.77) have been obtained with 2 g L−1 adsorbent zeolitic material doses. A value-added material is obtained and applied in a preliminary way to solve a problem generated by the volcanic ash itself, allowing the End of Waste status and meeting different objectives of the sustainable development goals of the UN Agenda 2030. [ABSTRACT FROM AUTHOR]

Sodalite as one prototype of zeolite-type crystal structures contains a β-cage with a pore size of ∼2.7 Å and can capture small-sized molecules such as ammonia and water. However, the low thermal stability of sodalite stemming from the presence of hydroxyl groups in the aluminosilicate framework adversely affects its high-temperature applications. Herein, a novel strategy for synthesizing a sulfatic modification of sodalite (S-sodalite) without any hydroxyl group in the framework, except water molecules in the cage, has been successfully developed. S-Sodalite was hydrothermally recrystallized from a gel, which was first digested from basic sodalite (B-sodalite) by sulfuric acid (H2SO4) and neutralized by alkali. Thermogravimetric analysis in combination with powder X-ray diffraction shows that the framework of S-sodalite has exceptionally high thermal stability up to at least 900 °C, which is attributed to the incorporation of the SO42− group rather than OH− into the structure. The robust framework of S-sodalite avoids the 14.5% volume expansion accompanying the conversion of hydrosodalite to anhydrous sodalite, which can cause cracking and affect applications. In addition, nitrogen (N2) adsorption–desorption measurements show that the specific surface areas of the nanocrystalline microspheres of S-sodalite are greatly enhanced to 48.8 m2 g−1 from 0.8 m2 g−1 of micro-sized B-sodalite. The adsorbed amount of ammonia (NH3) reaches 1.78 mmol g−1 at 25 °C under a pressure of 1 bar. Therefore, the new strategy for the synthesis of hydrophilic S-sodalite with exceptionally high thermal stability paves the way for its potential applications of water removal from mixed gases at elevated temperatures. [ABSTRACT FROM AUTHOR]

This article explores the rarity of green haüyne gemstones, which are typically known for their blue color. However, greenish blue and green variations have been discovered in Afghanistan and Tanzania. The Gems and Precious Metal Testing Laboratory of the Gem and Jewelry Institute of Thailand examined seven green haüyne gemstones, confirming their haüyne properties. The article provides a scientific analysis of the gemstones' physical properties, microscopic observations, and chemical analyses. This study is the first to describe gem-quality green haüyne. [Extracted from the article]

Despite numerous studies focused on the hydrothermal (HT) synthesis of fly ash zeolites (FAZs), this method still has many limitations, the main of which is the low yield of zeolites. Hydrothermally synthesized zeolites are typically multiphase and exhibit low purity, which limits their applicability. Pure-phase zeolites have been primarily prepared from filtrates after alkaline mineralization of fly ashes, not directly in suspension. In addition, the published methodologies have not been tested in a wider set of samples, and thus their reproducibility is not confirmed. The aim of the study is to propose a reproducible methodology that overcomes the mentioned limitations. The influence of the Si/Al ratio (1.3:1–1:2), the type and concentration of the activator (2/4 M NaOH/KOH/LiOH), the reagent (30% LiCl), the duration (24–168 h), and the temperature (50–180 °C) of the synthesis phases were studied. The sequence of the synthesis phases was also optimized, depending on the type of heat transfer. The fly ashes were analyzed by wavelength-dispersive X-ray fluorescence (WD XRF), flame atomic absorption spectrometry (F-AAS), and X-ray diffraction (XRD). The energy intensity of the synthesis was reduced through the application of unique microwave digestion technology. Both microwave and combined (microwave and convection) syntheses were conducted. FAZs were identified and quantified by XRD analysis. This study presents a three-stage (TS) hydrothermal synthesis of pure-phase sodalite in suspension. Sodalite (>99 wt.%) was prepared from nine fly ashes under the following conditions: I. microwave phase: 120 °C, 150 min, solid-to-liquid ratio (S/L) 1:5, Si/Al ratio 1:1.5, and 4 M NaOH; II. convection phase: 120 °C, 24 h, S/L 1:40, and the addition of 30 mL of 30% LiCl; and III. crystallization: 70 °C for 24 h. The formation of rhombododecahedral sodalite crystals was confirmed by scanning electron microscope (SEM) images. [ABSTRACT FROM AUTHOR]

The new mineral pilanesbergite, with the ideal formula Na 2 Ca 2 Fe 2 Ti 2 (Si 2 O 7) 2 O 2 F 2 , was found in a nepheline syenite, locally known as green foyaite, from the Pilanesberg Complex located in the North West Province of South Africa. Pilanesbergite occurs in green foyaite in association, and partly intergrown, with aegirine. The two minerals share an assemblage of inclusions, comprising euhedral nepheline, titanite and minor sodalite. Pilanesbergite belongs to the wöhlerite group and is isomorphic with låvenite, normandite and madeiraite. It is related to these species through the homovalent chemical substitutions Mn2+↔Fe2+ and Zr4+↔Ti4+. The empirical formula calculated on the basis of 18 anions is Na 2.00 (Ca 1.74 Na 0.26) Σ2.00 (Fe 1.00 Mn 0.52 Ca 0.49 Zr 0.05) Σ2.06 (Ti 1.69 Zr 0.14 Mg 0.09 Nb 0.08) Σ2.00 (Si 2 O 7) 2.00 O 1.84 F 2.16 (Z=2). The new mineral is translucent with a brown orange colour and a brownish streak. The Mohs hardness is estimated between 5 and 6 by comparison with låvenite, and no cleavage is observed. Measured and calculated densities are Dmeas=3.47 g cm -3 and Dcalc=3.40 g cm -3. In the thin section the pleochroism is strong, between straw yellow and orange red, while in immersion the strong pleochroism is observed between light yellow (α) and yellowish orange (γ). The crystals are optically biaxial (+) with α=1.743(3) , β=1.768(3) , γ=1.795(5) and a 2 V angle close to 90 ∘. The crystal structure is monoclinic (P 2 1 / a), with the unit-cell parameters a=10.7811(2) , b=9.7836(1) , c=7.0348(1) Å, β=108.072(2) ∘ and V=705.41(2) Å 3 , and has been refined to R1=2.06 %. The strongest lines of the powder X-ray diffraction pattern [ d , Å (I , %) (h k l)] are 3.219 (60) (310), 2.851 (100) (12-2), 2.802 (51) (320), 2.743 (27) (22-2), 2.423 (19) (40-2) and 1.723 (19) (44-2). Pilanesbergite formed under relatively reducing conditions from an agpaitic nepheline syenite magma that had evolved by fractional crystallization mainly of aegirine. Further crystallization of arfvedsonite caused an increase in oxygen fugacity and a change towards higher Mn/Mn+Fe of the magma, causing a change of mineral composition from pilanesbergite towards normandite. [ABSTRACT FROM AUTHOR]

Conditioning of radioactive waste generated from the operation of medical institutions, nuclear cycle facilities, and nuclear facilities is important for the safety of the environment. One of the most hazardous radionuclides is radioactive cesium. There is a need for more effective solutions to contain radionuclides, especially cesium (Cs+). Geopolymers are promising inorganic materials that can provide a large active surface area with adjustable porosity and binding capacity. The existence of nanosized zeolite-like structures in aluminosilicate gels was shown earlier. These structures are candidates for immobilizing radioactive cesium (Cs+). However, the mechanisms of their interactions with the aluminosilicate framework related to radionuclide immobilization have not been well studied. In this work, the influence of alkaline cations (Na+ or K+) and the aluminosilicate framework structure on the binding capacity and mechanism of interaction of geopolymers with Cs+ is explored in the example of a sodalite framework. The local structure of the water molecules and alkaline ions in the equilibrium state and its behavior when the Si/Al ratio was changed were studied by DFT. [ABSTRACT FROM AUTHOR]

Herein, we reported that the platinum (Pt) clusters encapsulated into sodalite (SOD) zeolite as catalyst exhibited 100 % selectivity at 100 % conversion in the selective hydrogenation of p‐chloronitrobenzene to p‐chloroaniline via hydrogen spillover. The direct interaction between p‐chloronitrobenzene and encapsulated Pt was prevented by the shape selectivity of SOD zeolite, reactants were thereby adsorbed onto zeolite outer surface to facilitate the hydrogenation proceeding by hydrogen spillover process. The further kinetic study and DFT calculation showed the excellent catalytic selectivity was ascribed to the much faster rate of hydrogenation of adsorbed nitro group than that of adsorbed C−Cl group. [ABSTRACT FROM AUTHOR]

Photochromic sodalites are considered for a plethora of possible applications, such as UV indexing and X‐ray imaging, but for many of these the materials are yet to be optimized. UV indexing can be improved through incremental adjustment of the activation energy of coloration from 300 to 410 nm through replacement of sulfur with selenium. By combining this and other methods of tuning presented in the literature, the excitation threshold and photochromism color can be tuned independently of one another. The range of possible absorption maxima is expanded to 420–680 nm, or almost the entire visible spectrum. Mixing low‐cost and easy‐to‐synthesize sodalites further broadens the possible range of colors and facilitates development of a unique sodalite mix capable of quantifying the doses of two types of UV radiation simultaneously. Finally, the response to X‐rays of these highly tuned sodalites is investigated, and it is found that they can be sensitized to produce clear, high‐contrast X‐ray images at significantly lower doses of radiation than those required by classic photochromic sodalite, Na8(AlSiO4)6(Cl,S)2. [ABSTRACT FROM AUTHOR]

[Display omitted] Metal-organic framework (MOF) materials are promising precursors to transition into metal-nitrogen-carbon (M-N-C) catalysts with high catalytic performance. Pyrolysis is one of the most common ways to convert MOFs into electrically conductive MOF-derived M-N-C catalysts. General interests in using MOFs as precursors derive from changing the MOFs' porous structure into the carbonaceous frame. However, this favorable structure is not always maintained, with the reason unidentified since pyrolysis is currently still more of an empirical process. Understanding the pyrolysis processes leading to the transformation of MOFs into M-N-C catalysts is essential to broaden the development of MOF-derived catalysts. We report here complete chemical and morphological evolution and transformation of two commercial MOFs with the same sodalite topology, the ZIF-8 and ZIF-67, via series of in situ and ex situ techniques. The results reveal that the structure of the ZIF-67 collapses after the pyrolysis due to the graphitization of the carbon. Graphitization is catalyzed by the metallic cobalt particles formed when the temperature rose above 460 °C. The ZIF-8 was found to be a promising precursor material since most of the metal evaporates at the early stages and does not aggregate to form metal particles. However, the insufficient metal-N active sites and intrinsic low electrocatalysis availability of Zn limit the performance of the final catalyst. To maintain the porous structure of MOFs it is important to control the metal species and prevent them from agglomeration. Direct utilization of high-concentration MOFs as pyrolysis precursors is not recommended without rational design to inhibit agglomeration and graphitization that are undesirable for catalyst activity. [ABSTRACT FROM AUTHOR]

As a flexible porous material, the amorphous behavior of zeolitic imidazolate framework‐8 (ZIF‐8) has garnered considerable interest. However, the association between its strain behavior and topology has not yet been exhaustively studied computationally. We perform molecular dynamic simulations on both ZIF‐8 and its topological silicate isomer sodalite (SOD) to investigate the pressure‐induced development of the mid‐ and short‐range structures. We find that both ZIF‐8 and SOD undergo two successive transformations. The first is the amorphization process, which is characterized by the breakdown of the mid‐range structure without a significant change in the elastic modulus. The other type of densification involves a change in the short‐range structure, during which the mechanical properties are improved as the short‐range disorder increases. [ABSTRACT FROM AUTHOR]

Using the mixed solution of n -butanol and ethanol as solvent, the sodalite nanocrystal aggregate was prepared by the solvothermal method. The influences of crystallization temperature, molar ratio Na/Al, crystallization time and silane concentration on the morphology, crystallite size, degree of crystallization and pore structure of the as-prepared samples were investigated by X-ray diffraction (XRD), BET, FTIR, Transmission Electron Microscopy (TEM) and scanning electron microscope (SEM). The results reveal that the sodalite nanocrystals are aggregated by self-assembly into the micropore–mesopore–macropore structure. Higher crystallization temperature and longer crystallization time are conducive to the growth of sodalite nanocrystals. It is a necessary condition for the formation of sodalite nanocrystals to keep high molar ratio Na/Al. The higher the molar ratio Na/Al, the more favorable the crystallization of sodalite nanocrystals. The appropriate concentration of silane agent is conducive to the preparation of smaller crystal-sized sodalite nanocrystals. After removing the silane agent by pickling, the sodalite nanocrystal aggregate is a multistage porous structure with the pore volume of 1.0133 mL/g and the specific surface area of 449.73 m2/g. The preparation of nanocrystal sodalite by solvothermal method, the introduction of Hexadecyltrimethoxysilane as a surfactant, followed by acid pickling to remove the surfactant, produced multistage porous sodalite nanocrystal aggregate, greatly improving the mass transfer rate of sodalite, making it applicable to a wider range of fields. [ABSTRACT FROM AUTHOR]

The new sodalite-group mineral species slyudyankaite, ideally Na28Ca4(Si24Al24O96) (SO4)6(S6)1/3(CO2)·2H2O, was discovered in altered lazurite-bearing metasomatic rock at the Malo-Bystrinskoe gem lazurite deposit, Baikal Lake area, eastern Siberia, Russia. The associated minerals are diopside, calcite, fluorapatite, phlogopite, lazurite, and pyrite. Slyudyankaite forms green to pale blue isolated anhedral equant grains up to 0.5 cm across and their aggregates. The streak is white and the luster is vitreous. Slyudyankaite is brittle, with a Mohs hardness of 5½. Cleavage and parting are not observed. Density measured by flotation in heavy liquids is equal to 2.46(2) g·cm–3. Density, calculated using the empirical formula and unit-cell volume refined from single-crystal XRD data, is 2.454 g·cm–3. Slyudyankaite was characterized using the IR, Raman, ESR, near infrared (NIR), visible (Vis), and ultraviolet (UV) absorption, XPS and photoluminescence spectroscopy methods. The chemical composition is (wt%, electron microprobe, H2O and CO2 determined by selective sorption of ignition products, CO2 confirmed by quantitative IR spectroscopic method, sulfate sulfur determined by wet chemical analysis): Na2O 19.28, K2O 0.12, CaO 5.13, Al2O3 27.01, SiO2 33.25, SO3 10.94, S 1.75, Cl 0.10, CO2 1.42, H2O 0.90, –O≡(Cl,HS) –0.03, total 99.87. The empirical formula is Na27.57Ca4.05 K 0.11 S i 24.52 A l 23.48 O 96 S O 4 6.06 S 2.42 0 C l 0.12 C O 2 1.43 ⋅ 2.21 H 2 O where S 2.42 0 is the total sulfide sulfur, mainly occurring as neutral S6 and subordinate S4 molecules, according to the structural data. XPS spectroscopy confirms the presence of sulfide sulfur in neutral form. The crystal structure was determined using single-crystal X-ray difraction data and refined to R = 0.0428. Slyudyankaite is triclinic, space group P1, a = 9.0523(4) Å, b = 12.8806(6) Å, c = 25.681(1) Å, α = 89.988(2)°, β = 90.052(1)°, γ = 90.221(1)°, V = 2994.4(2) Å3, Z = 1. Slyudyankaite contains two kinds of sodalite cages occurring in the structure in a ratio of 3:1. Cages of the first kind are completely occupied by S O 4 2 − anions and extra-framework cations, whereas cages of the second type contain only neutral molecules (S6, CO2, H2O, and minor S4). The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 6.45 (11) (004, 112, 020), 3.716 (100) (204, 220, 116, 132), 2.878 (12) (136, 028, 044), 2.625 (23) (208, 240), 2.431 (6) (209), 2.275 (6) (048), 2.143 (12) (0.0.12, 336), 1.784 (7) (444, 1.1.14, 356, 172). [ABSTRACT FROM AUTHOR]

An extrusive rock unit in the Mesoproterozoic Pilanesberg alkaline complex that has been referred to as the "Beacon Heights Tinguaite" since the work of Shand (1928) has been reexamined in the field and studied by petrographic microscopy, scanning electron microscopy, and whole-rock major and trace element analysis. The new observations indicate that the unit (here informally renamed the "Beacon Heights Phonolite" to comply with current petrographical nomenclature) is a laminated, volcanic rock in which mafic layers rich in sodic pyroxene alternate on any scale with discontinous, felsic layers consisting of alkali feldspar, nepheline, sodalite and their alteration products natrolite and analcime. Highly strontian apatite, fluorite, a manganiferous pectolite-group mineral, sphalerite and pyrrhotite are minor to accessory minerals. In addition, the rock carries indicator minerals typical of agpaitic rocks (including lamprophyllite and eudialyte-group minerals and their replacement products). The rock contains abundant crystal fragments of felsic minerals (alkali feldspar, nepheline and sodalite), fragments and elongated lenses of nepheline syenite, some of which contain primary magmatic lamprophyllite, and rare armoured lapilli. The overall structure of the rock is that of a welded ashflow tuff (igmimbrite) affected by post-magmatic recrystallisation processes. Whole-rock major and trace element compositions suggest a compositional affinity with members of the agpaitic, intrusive Green Foyaite Suite of the Pilanesberg Complex, and probably also a genetic relationship. The Beacon Heights Phonolite is a rare, possibly unique, example of an ashflow deposit of agpaitic, highly silica-undersaturated composition. [ABSTRACT FROM AUTHOR]

Hydroxyl sodalite and sulfate cancrinite were synthesized from fly ash from TPP Varna, Bulgaria. The interaction of the two feldspathoids with NH4NO3 solution at 90 °C was investigated. Because of the reaction, sodalite is dissolved and ammonium feldspar (buddingtonite) is formed, which is the first case of low-temperature synthesis of this mineral. The interaction of cancrinite with NH4NO3 induces ion exchange and the formation of cancrinite with composition (NH4)5.4Na3.6(NO3)1.45(SO4)0.25(OH)0.05[Al6Si6O24]·2H2O, suggesting potential for the use of this form as a slow-acting fertilizer. [ABSTRACT FROM AUTHOR]

The article discusses the discovery of orange sodalite gemstones from Badakhshan, Afghanistan. Sodalite is typically known for its dark blue color, but these stones exhibit a vivid orange hue. The stones were found in the Kokcha Valley and are believed to have slight photochromic properties. Testing confirmed their identity as sodalite and revealed that the orange color is stable, while the reddish-orange color is unstable and fades back to the original color. The article also briefly mentions spessartine, an orange gem material found in Loliondo, Tanzania. [Extracted from the article]

The paper presents experimental data on the interaction of amphibole with NaCl–H2O and (K, Na)Cl–H2O solutions at varying salt content. When interacting with H2O–NaCl fluid, amphibole remains the predominant mineral in all experiments, and the newly formed minerals are Na-phlogopite, plagioclase, and nepheline/sodalite. At > 0.6, the amphibole melts. When amphibole interacts with H2O–NaCl–KCl fluid at < 0.40 and ХKCl/(ХKCl + ХNaCl) in the fluid, defined as ХNaCl = 0.506 – 0.84ХKCl, the amphibole is replaced by the association of nepheline with sodic plagioclase, sodalite, and biotite. At ХKCl/(ХKCl + ХNaCl) > 0.3, nepheline, sodalite, and plagioclase become unstable, K-feldspar is formed, and biotite, clinopyroxene, and amphibole remain stable. At ХKCl/(ХKCl + ХNaCl) > 0.5, the association Cpx + Bt + Kfs + Grt (grossular–andradite) is stable. Thus, grossular–andradite garnet is an indicator of a high potassium activity in the fluid, whereas nepheline testifies that the sodium activity was high. Na → K exchange is typical of the amphibole and biotite, and Ca → Na exchange occurs in the clinopyroxene, and all of these minerals (but neither nepheline nor garnet) remain generally stable within a wide range of the K/Na ratio in the fluid. Clinopyroxene in the experiments spans Ca–Fe–Mg compositions with a varying, sometimes high, Al content, and the amphiboles belong to the pargasite–hastingsite series. With an increase in ( > 0.57), i.e., a decrease in the gross salinity of the fluid, melts are generated, and their composition varies from trachyte to phonolite. An increase in the ХKCl/(ХKCl + ХNaCl) ratio in the fluids leads to a decrease in alumina content of the melts. An increase in the total salinity of the fluid leads to an increase in the content of potassium in the melt and a decrease in the content of chlorine in it. The experiments have shown that interaction between amphibole and fluids containing high NaCl and KCl concentrations results in mineral associations typically produced by alkaline metasomatism of amphibole-bearing rocks and concomitant HCl enrichment in the fluid phase. The substitution of highly saline fluids for highly acidic ones leads to the leaching of Ca, Mg, Fe from the metamorphic rocks, and the transport and redeposition of these components. It follows that significant removal of FeO, MgO, CaO from rocks is sometimes a consequence of the interaction of the host rocks with saline aqueous solutions. [ABSTRACT FROM AUTHOR]

Two sodalite samples (sample I is Na8Al6Si6O24Cl2⋅0.4H2O from the Kovdor alkaline ultramafic massif with carbonatites in the Murmansk region, Russia, and sample II is Na8Al6Si6O24Cl2⋅0.2H2O from the Bayan Kol nepheline syenite and miaskite massif in the Republic of Tyva) were studied by thermal and electron-microprobe analyses, powder X-ray diffraction, photoluminescence, and by IR, Raman, and ESR spectroscopy. Solution melt calorimetry was applied to determine the enthalpy of formation from elements for water-bearing sodalite samples: −13536 ± 10 (I) and −13503 ± 19 (II) kJ/mol. The enthalpy of formation of sodalite of the theoretical composition Na8Al6Si6O24Cl2 was evaluated at ΔfH0(298.15 K) = −13446 ± 11 kJ/mol. The data obtained on the enthalpy of formation of sodalite and literature data on its S0(298.15 K) were used to calculate the standard Gibbs energies of formation of anhydrous and of water-bearing sodalite. [ABSTRACT FROM AUTHOR]

The article presents studies of the influence of parameters of synthesis modes and alkali concentration on the synthesis of zeolite materials from coal fly ash (CFA). The purpose of the study was to synthesise zeolite materials from CFA using the method of alkaline fusion and to determine the susceptibility of selected heavy-metal ions to removal from solutions in an ion exchange process on a selected mesoporous zeolite. It was found that the crystalline phase of sodalite was dominated in all of the samples synthesized. The specific surface area (SBET) of the samples was evaluated using the standard Brunauer–Emmett–Teller (BET) method using N2 sorption. Crystalline zeolite materials have been used to study the efficiency of removing heavy metals from aqueous solutions of Ni2+, Cd2+ and Pb2+. The adsorption data were analyzed using the Langmuir and Freundlich isotherm model. When comparing the estimated coefficient of determination (r2), it was noticed that the sorption data are more accurately described by the Langmuir isotherm and the pseudo-second-order kinetic model. The results of metal adsorption experiments suggest that the synthesized zeolite material has great potential to be used as an inexpensive and alternative source in the production of adsorbents. [ABSTRACT FROM AUTHOR]

The alkaline Cho Don complex in NE Vietnam comprises several mafic-felsic suites related to the widespread magmatism developed during the early Permian–late Triassic. The contribution explores the petrogenesis of nepheline syenite from the Bang Phuc massif and its petrogenetic relationship with cogenetic scapolite-rich gabbro. The nepheline syenite formed through fractional crystallization of pristine mantle-derived basaltic melt modified by subduction-related components (chiefly sediment-derived melts), as shown by, e.g. low Ba/Th and high Th/Nb ratios of the rocks. The transition from gabbro to syenite follows a within-plate enrichment trend (e.g. increasing Ta/Yb, Nb/Yb, and Th/Yb ratios) that might reflect switch from post-orogenic to intra-plate regimes, accompanied by subduction–collision–extension events related to the Indosinian Orogeny. Furthermore, magma evolution involved the progressive contribution of asthenospheric-derived melts that resulted in the appearance of OIB-like signatures (e.g. high Nb/La ratios) in the nepheline syenite. Fractional crystallization of fluorapatite and mafic phases, as well as assimilation of carbonate wall rocks ultimately led to the decrease of LREE contents and/or modification of Zr/Hf ratios. Magmatic phases of the nepheline syenite include nepheline, sodalite, oligoclase, orthoclase, and annite, as well as accessory fluorapatite, fluorite, and minor amounts of zircon and metamict allanite-Ce. The nepheline equilibrated at temperatures ranging between 850°C and 700°C, which reflects protracted residence at a higher temperature. Later, it has been locally altered to cancrinite, dawsonite, and natrolite via CO2- and alkali-rich fluid influx. The fluid–rock interactions were also manifested by the presence of chessboard-twinned albite and coarsening of braid-perthite into patch-perthite, as well as recrystallization of primary orthoclase into microcline. The orthoclase→microcline conversion, albeit fairly indiscrete under a polarizing microscope and confirmed by Raman micro-spectroscopy, is followed by the change of cathodoluminescence colours, i.e. from light-blue (activated by Ti4+ and/or Al-O—Al centres) in orthoclase towards brownish and/or greenish (activated by Mn2+ and structural defects) in microcline. [ABSTRACT FROM AUTHOR]

In recent years, nanocomposites based on biodegradable polymer and clay have received increasing interest and their development has become a very hot topic. Herein, it is reported a sustainable route across simple, lucrative ways and at low cost for synthesizing zeolite (sodalite), polycaprolactone and based polycaprolactone/sodalite nanocomposite. Sodalite was prepared from a broadly available kaolin depot from the west Algeria. Physical and chemical characteristics of the synthesized nanocomposite and its components are qualified using XRF, BET, TGA, XRD, SEM, AFM, and FTIR. Moreover, this article also includes a simple method for preparing dry powder specimens to AFM analysis, which showed a decrease in the surface roughness from kaolin to nanocomposite through zeolite. This research suggests the use of synthesized materials sodalite and nanocomposite as adsorbents for environmental remediation to eliminate pollutants due to their important measured characteristics for synthesized materials such as BET surface. [ABSTRACT FROM AUTHOR]

The residue from the Bayer process has physicochemical characteristics that allow its use in the production of synthetic aggregate, although some characteristics such as low plasticity and water absorption still need better control. In this work, the influence of clay and silica addition on the sintering of synthetic aggregate produced from bauxite residue was analyzed. Compositions containing bauxite residue-sand-clay were elaborated, whose processing occurred using extrusion and crushing, followed by sintering at 1200 °C for 3 h. The X-ray diffraction analyses indicated the presence of new phases such as nepheline, originating from sodalite, and mullite resulting from the decomposition of kaolinite. Increasing the amount of free silica in the mixture resulted in an aggregate with a higher bulk density and lower water absorption, indicating that the amount of this raw material influenced the aggregate properties. [ABSTRACT FROM AUTHOR]

Bystrite is redefined as a four-layer cancrinite-group mineral with the four-layer Losod-type framework and the end-member formula Na7Ca(Al6Si6O24)S52–Cl–. The mineral is known only at the Malo–Bystrinskoe gem lazurite deposit, Baikal Lake area, Siberia, Russia. The associated minerals are calcite, lazurite, sodalite, fluorapatite, phlogopite, diopside, dolomite and plagioclase. Bystrite is brittle, with the Mohs hardness of 5 and distinct cleavage on {101̅ 0}. The yellow colour of bystrite is due to the presence of S52– anions occurring in Losod (LOS) cages of the aluminosilicate framework with the ABAC stacking sequence. Measured and calculated density is, respectively, 2.43(1) and 2.412 g cm–3 for the holotype and 2.42(1) and 2.428 g cm–3 for the cotype sample. Bystrite is uniaxial (+), ɛ = 1.660(2) and ω = 1.584(2). The mineral was characterised by infrared and Raman spectra. The empirical formulae of the holotype and cotype samples are Na6.97K0.04Ca0.98(Si6.03Al5.97O24)(S52–)0.93[(SO42–)0.15Cl0.83] and Na6.75K0.04Ca1.11(Si6.09Al5.91O24)(S52–)1.04[(HS–)0.17Cl0.85], respectively. Bystrite is trigonal, space group P31c. The unit-cell parameters are: a = 12.8527(6) Å, c = 10.6907(5) Å, V = 1529.4(1) ų and Z = 2. The strongest lines of the powder X-ray diffraction pattern [d, Å (I, %) (hkl)] are: 4.821 (32) (102), 3.915 (38) (211), 3.712 (100) (300), 3.307 (50) (212), 2.782 (18) (400), 2.692 (22) (401), 2.673 (30) (004) and 2.468 (23) (402). Isomorphism and genesis of bystrite-type minerals is discussed. Bystrite and its K,HS-analogue sulfhydrylbystrite, Na5K2Ca(Al6Si6O24)S52–(HS)–, are indicators of highly reducing conditions. [ABSTRACT FROM AUTHOR]

Cu x S derivatives perform high activity in MOR (methanol oxidation reaction) through the co-operation of Cu and S. In order to further improve their performance, the composition and structure are regulated through the co-growth process of copper sulfide heterojunction and SOD (sodalite code) zeolite framework. Under the hydrothermal condition, the introduced Cu0 and Cu+ ions are clustered on the zeolitic surface and inner cages. The S2- anions are selectively located at the zeolite cage to balance the framework charge arisen from the incorporation of Cu+. In the electrochemical process, the optimized Cu 2 S/SOD zeolite electrode reveals an extra high efficiency of 8847 A g−1 at an extra low overpotential of 0.374 V with an excellent resistance to catalyst poisoning in high concentration of methanol. This work opens up a new method for the design and industrial application of non-precious metal electrocatalysts with high energy density based on porous zeolite materials. In order to further improve their performance, the composition and structure are regulated through the co-growth process of copper sulfide heterojunction and SOD (sodalite code) zeolite framework. In the electrochemical process, the optimized Cu 2 S/SOD zeolite electrode reveals an extra high efficiency of 8847 A g−1 at an extra low overpotential of 0.374 V with an excellent resistance to catalyst poisoning in high concentration methanol system. This work suggests potential applications in the field of non-noble metal catalyst for improving energy conversion, which provides a new idea for the construction of high-performance DMFC. [Display omitted] • A novel Cu x S and SOD structured zeolite composite is as-synthesized in hydrothermal condition. • In electrochemical process, the Cu x S NP S in SOD nanocages performed high efficiency in MOR. • The catalyst revealed an excellent resistance to catalyst poisoning in high concentration methanol system. [ABSTRACT FROM AUTHOR]

The design and synthesis of novel electrode catalysts is an applicable strategy to improve the performance of direct methanol fuel cells (DMFCs). The catalyst is composed of molybdenum disulfide as the shell and nickel silicide-doped sodalite (MoS 2 /NiSi@SOD) as the core. A series of characterization results indicate that NiSi is highly dispersed in the nanosized SOD cage on the surface of the SOD zeolite at the crystal faces of (011), (102), and (201). A thin conductive protective cover is formed by MoS 2 on the surface of the zeolite. By the cyclic voltammetry (CV), the catalyst performs a maximum current density of 46.9 mA cm−2 (1250.1 A g Ni −1) with 10 M methanol while no remarkable catalyst poisoning and catalyst deactivation are observed. It is revealed that MoS 2 /NiSi@SOD under high catalysis activity protects the Ni from the drain in the alkaline electrolyte, leading to a broad application prospect as a noble-metals-free DMFC catalyst. The MoS 2 /NiSi@SOD composite material reveals high performance in MOR with an efficiency of 46.9 mA cm−2 and 1250.1 A g−1 in 10 M methanol. The novel electrochemical catalyst is composed of the NiSi NPs doped SOD structure nanocages as the core and the MoS 2 nano wafer as the shell and is as-synthesized under hydrothermal condition through a self-assembly process in a one-pot reaction. During the crystallization of the zeolite, the NiSi nanocrystals are generated and restricted in the nanosized SOD cages. And the MoS 2 shell near the zeolitic surface enhances the electronic transport efficiency and protects the NiSi NPs from the drain in the electrolyte during the electrocatalytic progress. The catalyst is characterized by high performance and low production cost, being a good candidate to replace noble metal catalysts in applications. [Display omitted] • The MoS 2 /NiSi@SOD catalyst has been synthesized in hydrothermal conditions. • NiSi nanoparticles are highly dispersed and located in the pore of the SOD zeolite. • The low-cost catalyst plays high performance in MOR without obvious catalyst poisoning and deactivation. [ABSTRACT FROM AUTHOR]

Synthesis and development of high-efficiency and low-cost adsorbents for treating of the wastewater containing heavy metal ions and/or dyes has been aroused worldwide attention in recent years. In this study, the coal gangue as the only supply of Si and Al was adopted to synthesize sodalite using hydrothermal method. Both the gangue and the synthesized sodalite were characterized in terms of composition and structure. Cd2+ ions, methylene blue and their mixture were employed to evaluate the adsorption performance of the materials. The results showed that the gangue could be converted into sodalite with a small amount of impurity minerals. The as-prepared sodalite could effectively remove Cd2+ ion, and methylene blue due to its low Si/Al ratio, relatively high specific surface area and exchangeable Na+ ion content. The maximum adsorption capacities of the sodalite for Cd2+ ions and methylene blue were up to 60 mg/g and 17.3 mg/g, respectively. The adsorption isotherm of the Cd2+ ion and methylene blue could be described by Langmuir model, and the adsorption processes were more consistent with the pseudo-second-order kinetics. Relatively low-cost sodalite/gangue mixtures could be used instead of pure sodalite for the removal of Cd2+ ion, methylene blue and their combined pollutants. The as-prepared sodalite and the sodalite/coal gangue mixtures appear to be good candidate for treating of the heavy metal ions and dye wastewater. [ABSTRACT FROM AUTHOR]