Synthesis Of Sodalite Research Articles

Full-components utilization: Study on simultaneous preparation of sodalite and separation of yttrium from coal gangue by chlorination roasting process

Kaolinite-type coal gangue is a solid waste from coal mining that contains valuable rare earth elements (REE) and kaolinite. The simultaneous recovery of REE and synthesis of functional materials utilizing kaolinite from coal gangue presents an opportunity for full utilization. This study introduces synchronous chlorination volatilization of REE and preparation of sodalite from coal gangue. Thermodynamic analysis revealed xenotime reacts directly with NaCl to produce YCl3 for volatilization with the presence of O2. The effects of various factors on yttrium recovery and sodalite synthesis, including temperature, time, additives, and NaCl dosage, were investigated. Optimal conditions were identified as roasting coal gangue with 13.3 wt% NaCl and 41.7 wt% Na2CO3 at 1000 ℃, resulting in 93.4% yttrium volatilization and a 100% conversion efficiency of sodalite. The addition of Na2CO3 was found to accelerate the transition from aluminosilicate minerals to sodalite, thus achieving an outstanding sodalite conversion efficiency. This approach offers a theoretical and practical foundation for the efficient utilization of solid waste.

Silica-rich Sodalite Synthesis: The Effect of Variations in Ultrasound Treatment and Hydrothermal Temperature

Silica-rich sodalite zeolite has been synthesized by ultrasound treatment and hydrothermal temperature variation. This study aimed to determine the effect of ultrasound treatment and hydrothermal temperature variations on the crystallinity, hydrophobicity, and structural properties of silica-rich sodalite zeolite. The synthesis was conducted by reacting a sodium aluminate and sodium silicate solution by varying Si/Al ratios of 20, 30, 40, 60, 80, and 90. The next step was to characterize the product. The product with the best crystallinity was used as a reference to determine the effect of ultrasound and hydrothermal temperature. The reaction gel was treated with and without ultrasound and hydrothermal using autoclave at 100, 150, and 200°C for 24 hours. The last step was the product characterization using XRD, FTIR, and GSA. The XRD showed similarity peaks at 2θ = 14.058°; 24.41°; 31.73°; 34.75°; 42.88°. The best crystallinity was silica-rich sodalite zeolite with a Si/Al ratio of 30. Meanwhile, silica-rich sodalite zeolite peaks were obtained at 2θ = 14.16°, 24.66°, 31.99°, 35.13°, and 43.39° by ultrasound treatment and hydrothermal temperature variation (100, 150, and 200°C). Ultrasound treatment revealed the presence of other peaks besides sodalite at 2θ = 19.05° and 27°, where these peaks were referred to as SAPO-56. In conclusion, the degree of crystallinity increased with increasing temperature, decreasing Si-OH/Si-O-Si showed increased hydrophobic properties. Increasing the hydrothermal temperature of 150 and 200°C with and without ultrasound treatment increased the surface area significantly to 114.137 m2/g and 160.717 m2/g, and the pore volume of sodalite with a Si/Al ratio of 30 to 0.318 cc/g and 0.274 cc/g.

PURE SODALITE SYNTHESIS, CHARACTERIZATION AND APPLICATION FOR HEAVY METAL IONS REMOVAL FROM AQUEOUS SOLUTIONS

Pure sodalites were successfully synthesized from kaolinite taking the advantages of alkaline fusion technique. The synthesized sodalites were then characterized via XRD, SEM/EDX, and FTIR methods. The efficiency of these sodalites for treatment of Cu2+, Zn2+ and Ni2+ ions in aqueous solutions was also scrutinized through batch adsorption experiments. Subsequently, the concentrations of Cu2+, Zn2+, and Ni2+ ions in final leachates were detected by ICP-OES analysis. Furthermore, the results proved that adsorption data fitted very well to Freundlich isotherm model assuming that the metal ions removal can be applied to multilayer adsorption. Moreover, the kinetics of the adsorption followed the pseudo-second-order model suggesting that the rate of adsorption process may be controlled by the chemical sorption. In brief, the synthesized sodalites excellent performance for heavy metal ions removal from aqueous solutions can shed light on their remarkable potential in purification applications. Additionally, considering high cost of the natural sodalite, synthesis of sodalites with homogeneous porous structure that can be used as great adsorbents would be profitable for environmental purposes.

Synthesis of Sodalite from Sepiolite by Alkali Fusion Method and Its Application to Remove Fe3+, Cr3+, and Cd2+ from Aqueous Solutions

The aim of this article is to study the sodalite synthesis from sepiolite through an alkali fusion method followed by hydrothermal process, and to investigate its application in heavy metal removal...

Hybrid silica as cues for understanding the role of water in dry zeolite synthesis

This work proposed the application of hybrid silica, with different surface hydration characteristics-behavior-properties, as silicon source in Sodalite synthesis, in order to demonstrate through experimental data that if zeolite formation is ruled by surface reactions, these may be dependent of water amount on the surface. The surfaces of the systems were investigated using of Attenuated Total Reflectance Fourier Transformed Infrared spectroscopy (FTIR-ATR) techniques, while the hydrophilic/hydrophobic behavior was studied by wettability using Static Contact Angle analyses. The influence of hydrophilic/hydrophobic properties and hydrated surface as well, on zeolite formation, was investigated through X-ray Diffraction analyses. The results agree with the proposal, showing a faster zeolite formation (24 h) when hydrophilic silica is used (SG2B), while the time of zeolite formation seems to increase according to increasing in silica hydrophobicity (24 h for SGC1B, 48 h for SGC8B and 72 h for SGC18B).

Direct Synthesis of Sodalite from Indonesian Kaolin for Adsorption of Pb2+ Solution, Kinetics, and Isotherm Approach

Indonesian kaolin was used as precursor for synthesis of sodalite. Synthesis parameters were optimized by varying the Si/Al ratios, stirring and aging conditions, and water composition. X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR), Scanning Electron Microscope-Energy Dispersive Xray (SEM-EDX), and Particle Size Analyzer (PSA) were used to characterize sodalite. The potential of sodalite as adsorbent for heavy metal Pb2+ ions removal from waste water was investigated in this work. The uptake adsorption capacities of sodalite was 90-100 mg/g from synthesized sodalite crystallized for 24 and 48 hours, and commercial silica. The kinetic of Pb2+ adsorption was a pseudo second order reaction and the adsorption coefficients was followed Langmuir adsorption isotherm.

Effect of temperature on the synthesis of sodalite by crystal transition process

Abstract In the study, sodalite was synthesized with the kaolinite as the raw material in the steam and air atmosphere by crystal transition method. It was found that the content of sodalite in products decreased first and then increased as the temperature increased from 200 °C to 800 °C. The difference of the reaction paths at different temperatures was the main reason for the decreasing sodalite. At 200–300 °C, kaolinite would directly transform into sodalite. At 400–800 °C, kaolinite would first transform into nepheline and then transform into sodalite. At relatively low temperatures (400–600 °C), the reaction rates were both lower, which resulted in the lower content of sodalite. The reaction temperature was suggested above 600 °C to ensure the high yield of sodalite for the treatment of radioactive wastes.

Synthesis of Sodalite from Indonesian Kaolin with Conventional and Alkali Fusion Method

Sodalite has been synthesized from Indonesian kaolin. Kaolin was converted into more reactive metakaolin using conventional and alkali fusion methods. In the conventional method, kaolin is calcined at a temperature of 700 °C for 3 hours. Meanwhile, in the alkali fusion method, the mixture of kaolin and NaOH was calcined at a temperature of 600 °C for 2 hours. The effect of synthesis parameters such as aging time and crystallization temperature was investigated in conventional methods. Besides that, the crystallization time was investigated in the alkali fusion method. Transformation of kaolin into metakaolin and synthetic products was characterized using X-ray diffraction (XRD), X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). The results showed that the kaolin structure contained a lot of quartz. In the conventional method, the kaolin structure cannot be converted into metakaolin. The synthesis product obtained from this method is a mixture of sodalite and quartz. Whereas, in the alkali fusion method, kaolin can be converted into metakaolin and sodium silicate. The synthesis product obtained is a pure sodalite.

Direct Synthesis of Sodalite from Kaolin: The Influence of Alkalinity

Alkalinity is one of the most important factors that influence the crystallization process of zeolite and the product properties. The influence of alkalinity on the synthesis of sodalite from kaolin without calcinations was reported in this research. The synthesis of sodalite using molar ratio of Na2O/Al2O3 = x, H2O/Na2O = 128/x and SiO2/Al2O3 = 2/x, where x was the variation of molar ratio of alkalinity: 10, 20, 30, and 40. The synthesis has done by stirring for 6 h, without aging, and the crystallization time was 24 h under hydrothermal method (100 °C). The products were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The X-ray diffraction pattern and infrared spectroscopy shown that pure sodalite was formed by using molar ratio of alkalinity 10, 20, and 30. The crystallinity and particle size increase along with increasing of alkalinity. Quartz was formed by using molar ratio of alkalinity 40.

Parameter Surveys on Glass-Bonded Sodalite Synthesis Conditions from Spent Salt Generated in Pyroprocess

A parameter-based survey of the synthesis conditions by a so-called pressureless consolidation method to fabricate glass-bonded sodalite waste form for stabilizing fission products generated in pyrometallurgical reprocessing of spent metal fuel was performed. The maximum temperature, the heating duration at the maximum temperature, the glass fraction in the initial material, and the weight load used for pressing the material were chosen as the variable parameters. Accordingly, modified conditions to reduce the maximum temperature and increase the weight load were selected for reducing the volatilized-salt ratio during the heating and the free-salt ratio in the product. By fabricating a simulated waste under the modified conditions, the effect of changing the conditions was confirmed. Leaching tests in pure water using the consolidated products fabricated under both reference and modified conditions showed that the stability of the products was not significantly deteriorated by modifying the heating conditions.

Glass-bonded iodosodalite waste form for immobilization of 129I

Immobilization of radioiodine is an important requirement for current and future nuclear fuel cycles. Iodosodalite [Na8(AlSiO4)6I2] was synthesized hydrothermally from metakaolin, NaI, and NaOH. Dried unwashed sodalite powders were used to synthesize glass-bonded iodosodalite waste forms (glass composite materials) by heating pressed pellets at 650, 750, or 850 °C with two types of sodium borosilicate glass binders. These heat-treated specimens were characterized with X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, thermal analysis, porosity and density measurements, neutron activation analysis, and inductively-coupled plasma mass spectrometry. For the best waste form produced (pellets mixed with 10 mass% of glass binder and heat-treated at 750 °C), the maximum possible elemental iodine loading was 19.8 mass%, but only ∼8–9 mass% waste loading of iodine was retained in the waste form after thermal processing. Other pellets with higher iodine retention either contained higher porosity or were incompletely sintered. ASTM C1308 and C1285 (product consistency test, PCT) experiments were performed to understand chemical durability under diffusive and static conditions. The C1308 test resulted in significantly higher normalized loss compared to the C1285 test, most likely because of the strong effect of neutral pH solution renewal and prevention of ion saturation in solution. Both experiments indicated that release rates of Na and Si were higher than for Al and I, probably due to a poorly durable Na-Si-O phase from the glass bonding matrix or from initial sodalite synthesis; however the C1308 test result indicated that congruent dissolution of iodosodalite occurred. The average release rates of iodine obtained from C1308 were 0.17 and 1.29 g m-2 d-1 for 80 or 8 m−1, respectively, and the C1285 analysis gave a value of 2 × 10−5 g m-2 d-1, which is comparable to or better than the durability of other iodine waste forms.

Ultrasonic vs hydrothermal method: Different approaches to convert fly ash into zeolite. How they affect the stability of synthetic products over time?

The action of direct sonication (US) versus conventional hydrothermal method (HY) was investigated to determine the differences in the crystallization mechanism of zeolite formed from fly ash. The results showed that ultrasonic energy is decisive in very fast faujasite and A-type zeolite transformation into more stable sodalite phase. The data display the main presence of sodalite together with a low amount of faujasite and zeolite A after the first 3 h of sonication. The full transformation of the latter two phases into sodalite takes place after 1 h more of treatment. The samples incubated by hydrothermal process for 3 h, instead, are characterized by the main presence of faujasite and A-type zeolites. The progressive synthesis of sodalite at the expense of the other two phases begins only after 4 h of treatment. The conclusion is that the crystallization of zeolites by ultrasonic and hydrothermal method proceeds via two different mechanisms. The data also show that the two approaches affect the stability of the synthetic products in a different way over the years.

Eco-Friendly Synthesis of Aluminosilicate Bromo Sodalite from Waste Coal Fly Ash for the Removal of Copper and Methylene Blue Dye

The synthesis of sodalite from fly ash seems to be one of the most promising alternatives as it has emphasis on value addition to the waste material. In view of this problem, this study investigated a working procedure for determining the degree of reaction of fly ash subjected to alkali activation at mild temperature, during the synthesis of bromo sodalite, \(\hbox {Na}_{8}[\hbox {AlSiO}_{4}]_{6}\hbox {Br}_{2}\). Obtained sodalite product was analyzed for their composition and physicochemical properties by X-ray diffraction, Fourier transform infrared spectroscopic analysis, inductively coupled plasma, Brunauer–Emmett–Teller surface area analysis, thermogravimetric analysis and scanning electron microscope. The crystal structures show cubic symmetry in a space group \(\hbox {P}{\overline{4}} 3\hbox {n}\). The unit cell parameter \(a = 8.930\) A, and the corresponding Al–O–Si angle is found to be \(140.5624^{\circ }\). The adsorption behavior of synthesized bromo sodalite has been studied in order to determine its applicability for the adsorption of the copper ion and methylene blue dye from their aqueous solutions. Factors influencing the adsorption process including contact time, sodalite concentration variation, copper ion and dye concentration variation were studied for adsorption of copper and methylene blue dye. Copper is removed due to two processes, viz adsorption and ion exchange, whereas methylene blue is removed due to only adsorption. The maximum adsorption capacity of synthesized sodalite was found to be 52.63 mg/g for copper ion removal and 45.46 mg/g for methylene blue dye removal. Thermodynamic parameters like Gibbs free energy (\(\Delta G^{\circ })\), entropy change (\(\Delta S\)) and enthalpy change (\(\Delta H\)) were calculated. Present adsorbent showed much better adsorption capacity for both copper ion and methylene blue as compare to reported low-cost adsorbents.

Solventless green synthesis of sodalite zeolite using diatomite as silica source by a microwave heating technique

Microporous zeolite sodalite can be simply synthesized by mixing, grinding and microwave heating the solid mixture of raw natural clay and pseudoboehmite without solvent. The sample obtained by microwave-assisted solventless route exhibits good crystallinity and high yield. This method is very efficient, rapid, economic, and environment friendly for the synthesis of sodalite.

Hydrothermal Synthesis of Sodalite on Alkali-Activated Coal Fly Ash for Removal of Lead Ions

Sodalite was prepared by Alkali fusion-desilication-hydrothermal method using fly ash as raw material and characterized by X ray diffraction and scanning electron microscope. In addition, the adsorption characteristics of Pb2+on the sodalite under different conditions were investigatedand the adsorption mechanism was studied by IRspectrum analysis. The results showed thatthe sodalitewith high crystallinity was prepared at the basicity of 2mol/L,crystallization time of 12 hours, and crystallization temperature of 90°C; The adsorption performance of sodalitehad significantly improved than the original fly ash, andit could effectively remove the Pb2+ with considerably lower dosage.; When initial concentration was 100mg/L and the dosage was 2g/L, the removal rate could exceed 99%; The improvement of the initial concentration were in favor of the increase of theadsorption capacity,but we should regulate the relationship between adsorptioncapacity and adsorption rateby adjusting the ratio of solid to liquid;. The adsorption capacity was increased with the increase of temperature and pH; Increasing ionic strength would inhibit the adsorption behavior.;The maximum adsorption capacity of 157.2mg/g was obtained by the Langmuir equation. Through infrared analysis, it can be inferred that the adsorption ofsyntheticsodalite is a physical adsorption. Now, research shows that thesodalite from fly ash has a remarkable removal effect on Pb2+. So, it can be used as an effective adsorbent for heavy metal disposal.

Synthesis of sodalite from Brazilian kaolin wastes

AbstractKaolin wastes from the Capim and Jari regions (Brazil) were used to produce sodalite under the same conditions used in the Bayer process, in order to control its formation when necessary. Of the two kaolin source materials, the kaolinite from the Jari region was more reactive in the synthesis of sodalite, which is attributed to the low degree of structural order of this clay mineral which increased its reactivity. At a temperature of 150°C and with a Na/Al ratio of 2, although the kaolinite did not react completely, sodalitewas the primary reaction product. An increase in the temperature to 200°C provoked the complete reaction of the kaolinite only for the products in which carbonate and sulfate were used. With a Na/Al ratio >2 and for both of the temperatures, the kaolinite reacted completely to form sodalite.

Ionothermal Synthesis of Sodalite from Metakaolin

The sodalite was prepared with metakaolin by the ionothermal method in deep eutectic solvent(choline chloride/urea). Such factors as the Na2O/SiO2 ratio, crystallization temperature and time had effects on the structure and property. The high crystallinity and purity of sodalite can be obtained at the Na2O/SiO2 ratio of 3:1, and the temperature of 180°C for 60h. The product was characterized by means of X-ray diffraction, Infrared spectrum and scanning electron microscopy.

Conditioning of Chloride Salt Wastes from Pyroprocesses Through the Pressureless Consolidation Process

Sodalite has been taken into account as a matrix for conditioning chloride salt wastes coming from pyroprocesses. The present paper illustrates the research activities finalized to demonstrate the feasibility of sodalite synthesis through the Pressureless Consolidation (PC) process, proposed by Idaho National Laboratories (INL) in USA. A homogeneous powder of nepheline, chloride salts and glass frit was put into an alumina crucible and slightly pressed with another alumina crucible of a smaller diameter, inside which a stainless steel bar had been inserted. The entire assembly was introduced in a furnace inside an Argon-atmosphere glove-box and heated at 925°C for 7hours. The product obtained has then been characterized by means of density measurements, thermal analysis, stereomicroscopy observations, as well as FTIR and XRD. The latter correspond to the ones of sodalite reported in the spectral library. Leach tests under static conditions according to ASTM C1285-02 (reapproved 2008) have been carried out and successfully compared with those obtained by INL.

A phenomenological–mathematical approach in simulating the loss in weight of chlorine during sodalite synthesis

In a previous paper we described the results of a sodalite synthesis, performed by the mixing of metakaolinite and NaCl within an alumina crucible, heated in an oven at a temperature of 850°C and ambient pressure. During the synthesis process, a loss of weight of the open crucible, attributed to chlorine (Cl) diffusion through the granular material contained inside the crucible, was observed. A very simple model was proposed, aimed at reproducing mathematically the experimental data behavior. Nevertheless, experimental and numerical result comparisons suggested the need for some modeling improvements. Thus, in this paper the already proposed analytical solution, based on the usual “first principles” approach, was modified through a backfitting phenomenological–analytical approach. We explored the assumptions that at the beginning of the experiment, the inventory of chlorine was completely or partially bound in the matrix, and that it was transformed into a gas free to diffuse only gradually over the transient. In addition, we explored the effect of full or partial variability in time of the diffusion coefficient. The apparent delay in the release of chlorine gas through the matrix mixture could be justified by an incomplete heating of the crucible at 850°C and/or by some structure change of the mixture during the synthesis processes, eventually resulting in changes of diffusion coefficient values. The influences of the actual measurement process on the mathematical modeling setting, in particular the removal of some quantity of substance for diffractometer analysis, are also discussed. The final numerical results show an excellent agreement with the experimental data. Finally, it is worth noting that, notwithstanding the proposed methodology is addressed to the specific problem, it could have application in different fields.

Different methods to synthesize sodalite, as a matrix for conditioning chloride spent salts from pyroprocesses

The pyrometallurgical processing of spent nuclear fuel generates a chloride salt waste containing alkali-metal, alkaline-earth, and some rare-earth fission products. Sodalite, a naturally occurring mineral containing chlorine, has been investigated as an immobilization matrix for this salt waste. To this end different routes for the synthesis of sodalite have been followed: on one hand, direct synthesis from kaolinite, metakaolinite, or from silica and sodium aluminate have been carried out; on the other hand, a synthesis from Zeolite 4A used for preliminary decontamination of the salt by ion-exchange has been performed. The former allows to condition the waste salt as a whole, whenever discarding an entire process salt batch becomes necessary; this is the case when an electrorefiner plant has to be decommissioned, or in the event of a severe process upset; the latter is more suitable for routine operations, which better require the clean-up of the salt and its recycle to the electrorefiner, thus avoiding the production of huge quantities of solidified wastes to be disposed of.