Amount Of SiO2 Research Articles

Mineralogical Characteristics and Their Usability as Gemstones of Jaspers in Altered Metavolcanics Belonging to the Topçam Formation, Tokat, Turkiye

The jaspers located in the Topçam Mountain, Tepeyurt region (Tokat, Turkey), were formed at green-colored metavolcanic levels within Permian–Triassic schists. The sizes of the jaspers generally vary from a few cm to 1.5 m, and their colors vary from grayish–reddish–brownish/blackish tones depending on the increase in the amount of Fe and Mn elements they contain. According to thin section and X-ray Diffraction (XRD) analysis examinations, it was determined that the composition of jaspers includes quartz, hematite, calcite, and pyrite. As stated by the Wavelength Dispersive X-ray Fluorescence (WDXRF) analysis results, it was observed that the amount of SiO2 in jaspers was 82.5%, and the amount of Fe2O3 was 15.5%. According to Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) analysis results, Fe and Mn impurities, which are thought to cause the color of jaspers, as well as the amount of Fe (6975.5 ppm–46,893.9 ppm–96,431.1 ppm) and the amount of Mn (935.9–3219.7–6040.4 ppm), caused a darkening in color tones (grayish–reddish–brownish/blackish). Cabochon cutting applications were made of jaspers taken from the study area. As a result of these applications, it has been determined that jaspers can be used as gemstones due to their properties, such as their workability, polish retention, and color and light reflection.

Conduction mechanisms and dielectric relaxations in ternary ZnO/Zn2SiO4/SiO2 composites for energy storage systems

In this paper, ZnO-based composite (ZnO/Zn2SiO4/SiO2) powders were prepared and investigated as a function of SiO2 added amount. Indeed, the X-ray diffraction patterns (XRD) confirm the formation of ternary ZnO/Zn2SiO4/SiO2 composites. The structural defects are shown to increase with the SiO2 amount. In addition, the SEM observations reveal agglomerated and heterogenic grain shape distribution. Furthermore, dielectric properties were investigated as a function of SiO2 added amount. The Nyquist plots are simulated by an electric circuit formed by a parallel distribution of resistance (R), capacitance (C), and a constant phase element (CPE), in all composites. Moreover, using the Jonscher's law, we demonstrate a change in conduction mechanism as a function of SiO2 content. Indeed, for the 10% SiO2 doping, the conduction process is ensured by defects such as Zn interstitial and the oxygen vacancies, consistent with the Correlated Barrier Hopping (CBH) model. Whereas, for the 20% SiO2 doping, the conduction is dominated by grain boundaries contribution, according to the Non-Overlapping Small Polaron Tunneling (NSPT) model. Besides, the 10% SiO2-doped composite exhibits localized relaxation process, while the 20% SiO2-doped sample reveals simultaneously long-range and localized relaxations. These variations, caused by the increase of SiO2 percent, can be explained by the influence of the growth of Zn2SiO4 phase, and subsequently the development of further interfacial defects. Accordingly, the composites display capacitive behavior, high permittivity, and low dielectric losses, which make them good candidates for energy storage systems.

High ecostoichiometric stability and accumulating SiO2 and NO3− as main physiological adaptive mechanisms for reed to adverse environments

Previous studies have shown that nutrients accumulation played important roles in resisting to stress resistance of plants. Our study examined the ecostoichiometric internal stability (EIS) of nutrients accumulation and, concomitantly identified the main resistant regulating substances and their contributions to stress resistance of reed (Gramineae) in arid desert areas. Plants (digging method) and soil samples (quartering method)) obtained from sand dune (SD), desert steppe (DP), interdune lowland (IL), saline meadow (SM) and wetland (W) habitats were brought back to the lab for nutrients analysis. Results indicated that soil nutrients differed obviously, while reed maintained relatively stable ratios of SiO2: N, N: K, and P: K when the eco-environments changed in different habitats. Furthermore, reed exhibits common adaptive characteristics by mainly accumulating large amounts of SiO2 (122.6–174.0 g/kg) and NO3− (166.1–216.6 g/kg), as well as moderate levels of soluble sugar (SS: 24.0–55.0 g/kg), which are mainly stored in leaves for stress resistance. The contribution of ions to stress resistance was 80.03%–91.15% (with SiO2 and NO3− accounting for 54.91%–63.10%), whereas the contribution of solutes was only 8.85%–19.97% (with SS contributing to 5.14%–10.91%) in different habitats. These findings suggest that maintaining relatively high EIS, while still accumulating SiO2 and NO3− as main physiological regulators might be an effective strategy for reed to positively respond to adverse habitats, which provide a strong theoretical basis and technical reference for searching useful methods for restoration and reconstruction of the degraded ecosystems in desert oasis regions.

Improving thermal conductivity of Al/SiC composites by post-oxidization of reaction-bonded silicon carbide preforms

High thermal conductivity aluminium-based silicon carbide (Al/SiC) composites were successfully fabricated through post-oxidization of reaction-bonded silicon carbide preforms (RS preforms), utilizing vacuum pressure infiltration technology. The study investigated the regulation of interfacial reactions in conventional sintering and reaction sintering. Conventional sintering introduced a large amount of SiO2, which negatively impacted the thermal conductivity of the Al/SiC composite, but the reaction sintering not. The proposed post-oxidization treatment of RS preforms effectively removed residual carbon from the SiC particle surfaces, thereby forestalling the formation of Al4C3. Furthermore, the post-oxidization treatment effectively formed lightweight SiO2 deposits onto the surface of SiC particles, improving Al-SiC interfacial wettability and reducing thermal resistance, thereby enhancing composite thermal conductivity. Notably, the thermal conductivity of the post-oxidized sample exhibited an increase of 6.5% compared to the untreated sample. The study also evaluated the impact of particle size distribution on volume fraction and thermal properties. The optimized Al/SiC composites yielded thermal conductivity, coefficient of thermal expansion, bending strength, and Young’s modulus values of 237.3 W/m K, 8.5 × 10−6/°C, 325 MPa, and 75.9 GPa, respectively.

Microstructure and properties of in situ TiC-reinforced Ti750 composite prepared by SPS

Purpose Titanium alloys and composites have proven to contain desirable properties for use at elevated temperatures. One such material is the Ti750 composite, which can be used at temperatures up to 750°C for a brief period. This paper aims the microstructure, phase compositions, apparent porosity and hardness of both sintered and heat-treated TiC reinforced Ti750 composites for consideration in aircraft engine design. Design/methodology/approach The fabrication of TiC-reinforced Ti750 composites was achieved through spark plasma sintering (SPS). To analyze the microstructure and X-ray diffraction, a scanning electron microscope (SEM) with model number S-3400N and a D8 advance model machine were used, respectively. The microhardness of the samples was measured using a Vickers hardness tester with model HV-1000. The research incorporated three solid solution treatments: 975°C/3 h/AC, 1,010°C/3 h/AC and 1,025°C/3 h/AC, along with a solid-solution aging treatment at 1,010°C/3 h/AC + 750°C/8 h/AC. Additionally, oxidation analysis was conducted on the samples. Findings The microstructures contained enhanced TiC and Ti5Si3 phases in the near a-Ti matrix. The microhardness of the sintered composite was over twice that of the matrix alloy, and its porosity was reduced by about 0.35%. The sample treated at 1,010°C/3 h/AC had the highest enhanced peaks and microhardness of 1,277.1 HV. After oxidation at 800°C for 100 h, the accumulated weight of the solid solution composite at 1,010 °C/3 h/AC was the lowest (3.0 mg.cm-2). The surface microstructure contained oxides of TiO2 and a spalling white area containing a small amount of Al2O3 and SiO2. Originality/value There is limited research on Ti-Al-Sn-Zr-Mo-Si-based TMCs using a combination of the SPS method. This study used SiCp as a reinforcement for the Ti750 matrix alloy. The consolidation of SiCp and Ti750 powders using the SPS method, heat treatment of the resulting TiC reinforced Ti750 composites and study of the microstructure and properties of the composites are not found in literature or under consideration for publication in any media.

Impacts of SiO2 on phase composition, microstructure, and electrical properties of ZnO-SrCO3-Co2O3 ceramics

ZnO-SrCO3-Co2O3-SiO2 varistor ceramics were fabricated using the solid state method. Structural, morphological characterizations and varistor characteristics of samples were systematically studied. Average grain size is gradually reduced from 13.74 to 6.67 μm, resulting in a simultaneous increase of breakdown gradient E1 mA from 157.14 to 339.29 V mm−1. An increase of doping amount of SiO2 from 0 to 0.50 mol% contributes to the positive influences on double Schottky barrier of ZnO-SrCO3-Co2O3 varistors. The sample doped by 0.50 mol% SiO2 exhibits the highest height of double Schottky barrier φB of 2.99 eV resulting in the high nonlinear coefficient α equal to 76.83 and small value of leakage current density IL less than 0.29 μA cm−2 among the samples, which may be attributed to the solid solution reactions of SiO2 and Co2O3 in grain boundaries. The fabrication of ZnO-SrCO3-Co2O3-SiO2 represents the low-cost, sustainable development and environmental friendliness, providing a high performance candidate material for dominant ZnO-Bi2O3 based varistor ceramics.

The Stabilization of Copper and Cadmium in The Hydrated CaO-CuO-SiO2 and CaO-CdO-SiO2 Composites

The stabilization of toxic metals in the stable matrices is quite well-known. Research on copper and cadmium stabilization in the CaO-CuO-SiO2 and CaO-CdO-SiO2 composites was conducted to study the characteristics of CaO-CuO-SiO2 and CaO-CdO-SiO2 composites as well as the Cu and Cd metals stabilization in the hydrated composites. The composites of CaO-CuO-SiO2 and CaO-CdO-SiO2 were synthesized by the solid-state reaction method. A stoichiometric amount of CaO, SiO2, Cu(NO3)2, and CdO were calcined at 1050°C for 4 hours. The synthesized compounds were further hydrated in a soaking time of 30, 60, and 90 days. The hydration produced calcium silicate hydrate that can stabilize metals. The Cu and Cd stability in CaO-CuO-SiO2 and CaO-CdO-SiO2, respectively, were tested using the Toxicity Leaching Procedure (TCLP) method. The hydrated and hydrated composite characterizations were performed using X-ray diffraction (XRD), Fourier Transform Infra-Red Spectrophotometer (FTIR), and Scanning Energy Mocroscopy-Energy Dispersive X-ray analyzer (SEM-EDX) and the Atomic Absorption Spectroscopy (AAS) methods. The composites mainly consist of Ca3SiO5, Ca2SiO4, Ca(OH)2, SiO2, and metal oxide of CuO, Cu2O, and CdO. The composites were able to stabilize ~100% of the heavy metals of Cu and Cd.

In-vitro bioactivity investigation and surface properties of a PMMA-SiO2 composite coating on SS-316L using the Sol-Gel technique

Surface modification of SS-316L using an organic and inorganic hybrid coating of polymethyl methacrylate (PMMA) and silicon dioxide (SiO2) is being conducted in the current investigation with crosslinking agent 3-aminopropyl tri-ethoxy silane (APTES). The solvent-gel method and dip coating with varying amount of SiO2 (i.e. 0.5, 1, and 1.5 wt.%) is used for surface modification. On the coated surface, Fourier transform infrared spectroscopy (FTIR) at 1000–1250 cm−1 reveals the crosslinking of silicon and PMMA. The coatings formed on SS-316L are homogenous, transparent, and free of defects and voids when seen macroscopically. A good crystallinity and presence of coated material can be seen from the X-ray diffraction and microstructure analysis of coated surface. The PMMA coating with 1.5 wt.% SiO2 has the most apatite crystals deposited on surface as observed with 7 days of immersion on simulated body fluid (SBF). These findings provide a solid link that coating SS-316L with SiO2 promotes bone bioactivity, and the PMMA+1.5 wt.% SiO2 coating can be employed on implants. The results of this study suggest a sustainable coating solution for improved bioactivity in medical applications and surgical instruments.

A high-resolution characterization of surface film formed on alloys 800 and 690 exposed to chloride and thiosulfate-containing solution at 300°C

PurposeThis paper aims to characterize the surface film formed on Alloys 800 and 690 in chloride and thiosulfate-containing solution at 300°C.Design/methodology/approachAlloy 800 and 690 were immersed in chloride and thiosulfate-containing solution at 300°C up to five days, and then the surface film was analyzed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and energy dispersive X-ray spectrometers (EDX).FindingsThrough static immersion experiments in a high-temperature and high-pressure water environment, the alloy samples covered by surface film after five days of immersion were obtained. The morphology of the surface film was characterized at both horizontal and cross-sectional scales using SEM and focused ion beam-TEM techniques. It was observed that due to the influence of the quartz lining, the surface film primarily exhibited a bilayered structure. The first layer contained a significant amount of SiO2, with a higher content of metal hydroxides compared to metal oxides. The second layer was predominantly composed of Fe, Ni and Cr, with a higher content of metal oxides compared to metal hydroxides.Originality/valueThe results showed that the materials of the lining of the autoclave could significantly influence the film composition of the tested material, which should be paid attention when analyzing the corrosion mechanism at high temperature.

Natural Light Rechargeable Night Peal-like Coatings for Expressway

Traditional roadway lighting is intended to provide safe guidance for drivers and pedestrians, but the large-scale application of roadway lighting has resulted in significant energy consumption and light pollution. However, road markings prepared by luminous coating are a kind of multi-functional road marking that can meet the needs of highway lighting at night and save energy. Here, CaAl2O4:Eu2+,Nd3+,Gd3+ blue long-afterglow phosphor is obtained by the high-temperature solid-state method, and the blue luminescent coating is synthesized by the blending method. The phase composition, microscopic morphology, luminescence properties and water resistance of the phosphor and luminescent coatings are characterized. The best components and processes of the luminescent coating are explored to meet the application of an expressway. Considering the afterglow’s performance, the optimal calcination temperature of the phosphor is determined to be 1300 °C. The afterglow of the phosphor can be over 8 h after 2 h of daylight excitation. The addition of 1.25% SiO2 to the luminescent coating improves the uniformity of the components, and the incorporation of 3.5% CaCO3 improves the denseness of the coating. When the coating thickness is 0.8mm, the luminescent coating can achieve the best luminous effect. After 120 h of immersion in water, the afterglow intensity of the luminescent coating reduced to 70% of the original, which has excellent water resistance. The blue luminescent coating with the addition of appropriate amounts of CaCO3 and SiO2 improves the dispersion as well as the densification of the components in the coating to achieve the best luminescent effect. In the Shenyang area, different weather conditions (cloudy, sunny, rainy) have no significant effect on the afterglow performance of the luminescent coatings, all of which can achieve over 5 h of afterglow and are suitable for expressways.

PREPARATION AND CHARACTERIZATION OF BENTONITE CLAY CATALYSTS FOR TRANSESTERIFICATION OF WASTE COOKING OIL INTO BIODIESEL

The development of low-cost green catalytic materials is crucial for the conversion of non-edible vegetable oils or waste materials into biodiesel. The research focuses on the preparation and characterization of aluminium pillared clay and NaOH-doped bentonite clay catalysts for biodiesel production from waste cooking oil using XRF, XRD, FTIR and N2 adsorption-desorption techniques. The molecular profile and functional group assessment of the biodiesel were done using GC-MS and FTIR respectively. XRF analysis revealed the presence of oxides in all samples. The amount of SiO2 in all samples was within the range of 35.303–39.199 wt%. Al2O3 increased from 15.560 to 19.11 wt%, while the interlayer cations decreased after pillaring. FTIR revealed the appearance of peaks which are characteristic of bentonite. The pillaring and impregnation of NaOH with bentonite led to a distortion of certain peaks' intensity, as evidenced by FTIR results. The pillaring caused an increase in BET surface area and pore volume compared to bentonite from 302.1 to 366.4 m2/g, and 0.186 to 0.189 cc/g respectively, while a decrease in surface area and pore volume was observed in NaOH/bentonite due to impregnation. The XRD data have shown the increase of basal d-spacing of pillared clay from 12.65 to 16.49 Å relative to bentonite with a decrease to 12.45 in the case of NaOH/bentonite. The catalysts prepared outperformed neat bentonite with NaOH/bentonite, resulting in the highest yield of (83 ± 1.80). GC-MS, FTIR, and physicochemical analyses confirmed the production of fatty acid methyl esters.

Sequential Infiltration Synthesis of Silicon Dioxide in Polymers with Ester Groups-Insight from In Situ Infrared Spectroscopy.

New strategies to synthesize nanometer-scale silicon dioxide (SiO2) patterns have drawn much attention in applications such as microelectronic and optoelectronic devices, membranes, and sensors, as we are approaching device dimensions shrinking below 10 nm. In this regard, sequential infiltration synthesis (SIS), a two-step gas-phase molecular assembly process that enables localized inorganic material growth in the targeted reactive domains of polymers, is an attractive process. In this work, we performed in situ Fourier transform infrared spectroscopy (FTIR) measurements during SiO2 SIS to investigate the reaction mechanism of trimethylaluminum (TMA) and tri(tert-pentoxy) silanol (TPS) precursors with polymers having ester functional groups (poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), polycaprolactone (PCL), and poly(t-butyl methacrylate) (PBMA)), for the purpose of growing patterned nanomaterials. The FTIR results show that for PMMA and PEMA, a lower percentage of functional groups participated in the reactions and formed weak and unstable complexes. In contrast, almost all functional groups in PCL and PBMA participated in the reactions and showed stable and irreversible interactions with TMA. We discovered that the amount of SiO2 formed is not directly correlated with the number of interacting functional groups. These insights into the SiO2 SIS mechanism will enable nanopatterning of SiO2 for low-dimensional applications.

FORMING AND PROPERTIES OF GLASSES MADE FROM TWO THAI BOTTOM ASHES

Industrial wastes are often an under-utilized source of raw materials. Bottom ashes resulting from incineration processes can contain various metal oxides, including many commonly used in glass making. This research studied the forming and properties of glasses made from two bottom ashes. Lignite bottom ash (BL) from Lampang, Thailand and a municipal solid waste incinerator bottom ash (BP) from Phuket, Thailand. Both bottom ashes were found to contain significant amounts of SiO2, CaO, Al2O3, and Fe2O3. After ball milling, the ashes were melted without additions, at temperatures from 1300 to 1500°C. The resulting glasses, as confirmed by XRD, were black and fully opaque, a result of the high Fe2O3 content. It was found that the BP glasses were slightly more refractory, had a greater average thermal conductivity of 1.52 W/m·K and a lower coefficient of thermal expansion (CTE) of 6.97x10-6/°C, compared to the BP glasses, which had an average thermal conductivity of 1.39 W/m·K and a CTE of 7.98x10-6/°C. The BL glasses also had a higher average density of 2.88 g/cm3 and a Vickers hardness of 6.29 GPa, compared to the BP glasses, with average values of 2.74 g/cm3 and 6.06 GPa, respectively. The increase of glass melting temperature up to 1450°C tended to improve the observed properties, followed by a decrease at 1500°C. Despite the atypical glass chemistry of the two bottom ashes, they were successfully melted to produce glasses and the measured properties demonstrated suitable potential to warrant further study.

Determining the characteristics of concrete in a historical building under the influence of climatic and biological factors

The object of this study was concrete samples of the cathedral and wall frescoes. The study solved the problem related to the destruction of concrete and wall frescoes under the long-term influence of biochemical and climatic factors. Samples of concrete for research and wall murals were obtained from a historic listed building. Using microbiological studies and scanning electron microscopy, damage to wall murals and concrete by microscopic fungi was established: Aspergillus fumigatus, Penicillium brevicompactum, Aspergillus niger, Cladosporium sphaerospermum. The study of concrete samples by the TPD-MS method showed the presence of an increased level of moisture and carbon compounds by 20 % in the test samples, compared to control. The sulfur content in all concrete samples was not significant. Determination of the mineral composition of concrete by X-ray diffraction showed the presence of Al2O3, 36–44 %, which indicates a significant clay content. The presence of NiTi, 53 %, and СoMg7O8, 46 %, in the concrete sample indicates the probable migration of the chemical elements of the paint pigments used to decorate the cathedral. The concrete control sample contained a significant amount of SiO2, up to 51 %, which is the main component of sand. A feature of the work is the determination of the corrosion effect on concrete under prolonged exposure to climatic and biological factors. The present study is distinguished by the use of non-destructive methods: microbiological studies, scanning electron microscopy, TPD-MS and X-ray diffraction to determine the destruction of concrete and wall frescoes of the building, which is a cultural heritage. The results of the study could be applied to the development and planning of restoration works for the restoration of buildings that have historical value

Thermal Equations of State of Magnesite: Implication for the Complex Mid‐Lower Mantle Seismic Scatterers

AbstractMagnesite (MgCO3) entering the lower mantle together with the subducted oceanic crust is an important carbon carrier. The reaction between magnesite and mantle minerals has been documented, but its influence on the density and velocity profiles of lower mantle remains unexplored. To decipher the deep carbon transportation and its associated effect, here we determined the thermal equations of state of magnesite up to 120 GPa and 2600 K using X‐ray diffraction in laser‐heated diamond anvil cells. The obtained thermal elastic parameters of magnesite facilitated a comprehensive understanding on the influence of magnesite‐SiO2 reaction, variation of carbon and SiO2 content, and temperature on the origin of lower‐mantle scatterers at 1,000–1,800 km depth. Our modeling revealed that the depth of the lower‐mantle VS scatterers is mainly controlled by the Al2O3 content in SiO2, while its magnitude depends on the SiO2 content. Along normal geotherm, the magnesite‐SiO2 reaction would occur before the post‐stishovite transition, consuming substantial SiO2 in the subducted oceanic crust. Depending on the amount of residual SiO2, the post‐stishovite transition can produce a 2.5–5.2 (2)% VS reduction, compatible with the observed seismic scatterers in Izu‐Bonin and Mariana subduction zones. Along slab geotherm, this reaction occurs after the post‐stishovite transition, generating a greater VS reduction of 4.4–6.4 (4)%. We thus propose that the reaction between sinking MgCO3 and SiO2 in the slab is one of the potential factors influencing the magnitude of the lower‐Vs scatterers at 1,000–1,900 km depth. Our results provide new insights into the deep‐mantle carbonate transportation influencing regional geophysics.

Suitability evaluation of selected sand geological formations for synthesis high purity crystalline silica, Iraq

This study aims determination if the sand collected from Injana and Dibdibba Formations are suitable for use as low-cost raw materials in the manufacture of high-purity crystalline silica. Sand is distributed in vast quantities within the two Formations, which occupy large portions of Iraq’s southern desert. Quartz is the predominant mineral phase, followed by calcite, feldspar, and dolomite respectively, based on mineral analysis data. SiO2 is the main oxide in sand with an average of (82.76%), (90.24%) and the rest of oxides are CaO (6.28%), (1.64%), Al2O3 (4.02%),(3.19%), Fe2O3(2.73%), (0.86%), K2O+ Na2O (2.05%), (2.51%), SO3(0.05%), (0.47%), MnO (0.01%), (0.03%) P2O2 (0.23%),(0.03%), and MgO (1.75%), (1.01%) in Injana and Dibdibba Formations respectively, which are considered as impurities impact the manufacturing properties of sand. The coprecipitation method, which produces high purity crystalline silica at a low cost, involves three steps: the first involves soaking raw sand powder in 2M HCl for 24 hours; The second involves mix purified sand with NaOH while stirring and heating it to 95C° to produce Na2SiO3; and the third involves adding 3M HCl to sodium silicate solution to produce Si(OH)4 and drying it to produce high purity of silica. The prepared silica got mineral analysis and chemical analysis. The synthesized silica was in the crystalline phase, according to the results of the mineral characterization. In synthetic silica of Injana and Dibdibba sand, The amount of SiO2 increased according to chemical analysis, reaching 96.62%, and 97.69% respectively, while all other oxides (impurities) were lowered to their lowest levels. FE-SEM revealed the existence of spherical, well-agglomerated synthetic silica particles within the size 28.6 nm and 24.76 nm in synthetic silica particles of Injana sand and Dibdibba sand respectively.

Vitrification of lead–bismuth alloy nuclear waste into a glass waste form

AbstractLead–bismuth eutectic (LBE), a promising coolant in advanced nuclear systems, can be activated by neutrons during nuclear reactor operations. The decommissioning of nuclear facilities would generate lead–bismuth (Pb–Bi) alloy‐contaminated nuclear waste. The current metallic nuclear waste treatment approach involves remelting followed by cementitious solidification. This increases the waste volume and the risk of radionuclide migration in groundwater. Therefore, this study developed a method for vitrification of Pb–Bi alloy waste. Different amounts of SiO2 were added at 750–1100°C in the air to turn the simulated LBE waste into glass waste form. The values of the normalized elemental leaching rates (Pb, Bi, Si, Te, and Ni) determined using the 28‐day static leaching test were less than .2 g m−2 d−1 and varied with SiO2 addition. Furthermore, a three‐stage evolution of the glass structure with SiO2 addition was proposed according to the structural analysis performed using Raman and X‐ray photoelectron spectroscopies. The evolution stages were as follows: (i) the stage of heavy metal transition from covalent to ionic heavy metals (7.5 wt% < SiO2 < 15 wt%), (ii) the stage of increase in bridging oxygen (15 wt% < SiO2 < 20 wt%), and (iii) the stage of domination of the Si–O network (20 wt% < SiO2 < 25 wt%). The evolution of the glass structure resulted in varying glass chemical durability. Finally, the glass‐forming region of (20–48)PbO–(35–70)Bi2O3–(7.5–25)SiO2 (wt%) and the temperature needed to melt those glasses were determined through the melting test, where radionuclides and toxic heavy metals showed undetectable volatilization during vitrification. Hence, turning LBE waste into glass waste form will be a potential approach for treating Pb–Bi alloy nuclear waste.

Short-range order and chemical compositions of glasses along the basaltic-rhyolite sub-alkaline join by Raman and FTIR spectroscopies

Six sub-alkaline glasses with compositions progressively shifting from the tholeiitic basalt (B100) end-member to the rhyolite (R100) end-member were investigated and analysed in the same frequency domain by both Raman and FTIR. This approach highlights spectroscopic similarities and differences such as positions, widths and intensities of Raman and FTIR bands, which may also exhibit significant overlapping. Both the Raman and FTIR spectra show several peaks grouped in three main vibrational windows: 200–650 (low frequency region, named F-I in this study), 650–850 (intermediate region, F-II) and 850–1250 cm−1 (high-frequency region, F-III). In line with previous investigations, the F-I interval can be ascribed to vibrational modes involving rings of tetrahedrally coordinated cations linked by bridging oxygens. It can be fitted with three components, whereas F-II involves the motion of Si atoms within its oxygen cage and is adequately represented by two components. Finally, F-III contains different T-O (T = tetrahedrally coordinated network-forming cation) stretching bands that can be tied to the overall degree of polymerization of the glass and are fitted with four components. In some glasses, the three and the two components within F-I and F-II are identifiable in both Raman and FTIR spectra; in cases of strong peak overlap, these peaks can be complementary to one another towards our interpretation of the molecular arrangement(s) in these glasses. Indeed, the positions of the four components in F-III are first constrained in the Raman spectra, which are more identifiable, then further refined using available Raman spectra for corresponding chemically simple silicate systems. The nine fitted components can reproduce the Raman and FTIR spectra extremely well.As a function of the amount of SiO2, the positions and intensities of the three low frequency components progressively shift in both Raman and FTIR. Similarly, the two bands in the F-II intermediate region exhibit a monotonic shifting of their positions. Indeed, the components at high frequency display less significant shifting of their positions as a function of SiO2, while their intensities change more markedly in the Raman spectrum compared to those for FTIR. The vibrational components measured in this study provide a referenced dataset of assignations of the most abundant natural volcanic glasses. Therefore, it provides a diagnostic tool based on the cross-validation of Raman and FTIR spectra to quickly identify the glass chemistry, offering the possibility to expand the applicability of remote investigations.

Removal of anionic dyes from wastewater using fly ash based adsorbent

Facing the great challenge of increasing solid waste and huge amount of wastewater, “treating the wastes with wastes” seems to be a proper and sustainable development method. Fly ash, a typical solid waste, has attracted much attention for its high-value applications. In this study, three types of fly ash were sampled from different power stations in China and used for multiple anionic dyes wastewater adsorption. According to the static adsorption, fly ash sourced from Chifeng (CF) was identified as Class C with a total amount of SiO2, Al2O3, and Fe2O3 of 67.65% via chemical composition analysis, and presented best adsorption performance on Reactive Brilliant Red K-2BP, Congo Red 4BS, and Acid Brilliant Red KN. Moreover, the pseudo-second-order kinetic fitted the adsorption processes of KN and 4BS with the theoretic adsorption capacity of 39.35 and 39.85 mg/g, respectively. However, the pseudo-first-order kinetic better described the adsorption process of K-2BP with the theoretical adsorption capacity of 43.24 mg/g. For the dynamic adsorption, the decolorization rate of K-2BP on CF increased from 82.6% to 96.5% as the flow velocity increased from 10 to 70 rpm. The metal cations on CF, such as Fe3+ and Al3+, could hydrolyze and work as flocculants and coagulants to remove dye molecules from wastewater. This study provides a research case and an application potential for the resource reutilization of fly ash to treat printing and dyeing wastewater.

GAM-7: an organic-inorganic hybrid layered aluminophosphate crystal formed by zeolite transformation.

The interzeolite conversion (IZC) of metallo- and aluminophosphate zeolites was demonstrated using a non-cyclic secondary amine, diisopropylamine, as the organic structure-directing agent (OSDA). The IZC of AlPO4-5 with AFI topology could successfully produce an unknown highly crystalline phase, named GAM-7. In metallo-aluminophosphates (metal-AlPOs), SAPO-5 with a small amount of SiO2 was also interconverted to a single crystal GAM-7, designated as [Si]GAM-7. However, in other metal-AlPOs, the corresponding GAM-7 crystals were formed as either an intermediate or a mixture of plural crystals. Additionally, it was found that GAM-7 could also be obtained by hydrothermal synthesis (HTS), but not synthesized from a silico-aluminophosphate hydrogel, indicating that [Si]GAM-7 can be prepared by only the IZC technique. The obtained GAM-7 crystal was well-characterized to elucidate the framework structure, and this revealed that GAM-7 was a new organic-inorganic hybrid layered aluminophosphate having a terminal POH group in the corrugated layered sheets, and the OSDA molecule between the layers was robustly interacting with an acidic POH site by a hydrogen bond. Furthermore, we have performed the tracking of pH values during the transformation from AlPO4-5 into GAM-7 and have argued a reasonable consideration for the IZC process.