NaA Zeolite Research Articles

CO2 Adsorption Properties of Amine-Modified Zeolites Synthesized Using Different Types of Solid Waste

In this study, organic amines were used to modify zeolite NaA and analcime synthesized using fly ash and iron tailing slag as raw materials, respectively, and the adsorption properties of the modified zeolites toward CO2 were determined. We found that when tetraethylenepentamine (TEPA) was used, the modified zeolite NaA and analcime had the highest nitrogen content. The adsorption capacity of the modified zeolite NaA for CO2 was 4.02 mmol/g and that of the modified analcime was 1.16 mmol/g when the adsorption temperature was 70 °C and the CO2 flow rate was 50 mL/min. According to the adsorption isotherm, kinetic, and thermodynamic model fitting, the adsorption surface of the modified zeolite was not uniform, and the CO2 adsorption of the modified zeolites was classified as chemical adsorption. In a mixed atmosphere of 15% CO2/85% N2, the dynamic selection coefficients of the modified zeolite NaA and analcime for CO2 were 3.8942 and 2.9509, respectively; thus, the two amine-modified zeolites had good selectivity for CO2. After five cycles, the adsorption efficiencies of the modified zeolite NaA and modified analcime for CO2 were 92.8% and 89%, respectively. Therefore, the two amine-modified zeolites showed good recycling performance.

MnFe2O4/zeolite composite catalyst for activating peroxymonosulfate to efficiently degrade antibiotic

To design a catalyst with high catalytic activity and reusability for activating peroxymonosulfate (PMS) to degrade antibiotic, magnetic MnFe2O4/zeolite (MFZ) catalyst was prepared by one-pot co-precipitation hydrothermal method. Comprehensive characterizations indicate MnFe2O4 nanoparticles were supported on the surface of Na-A zeolite. The saturation magnetization of MFZ is 12.85 emu/g, which is sufficient for magnetic solid–liquid separation. The removal of tetracycline in MFZ/PMS oxidation system could reach 96.4%, which was more than 2.7 times of that using PMS alone. And after 5 cycles, the degradation could still reach 80.4%. Mechanism analysis suggests that 1O2 and O2•- played predominant roles in the advanced oxidation process.

Highly efficient and selective Hg(II) adsorbent: ZnS grown on the surface of 4A zeolite and supported on starch aerogels

In this study, ZnS nanoparticles were loaded on the surface of zeolite NaA and embedded in a carbon aerogel to prepare C@zeolite-ZnS, where zeolite NaA was used in order to adsorb Zn2+ ions released during ion exchange, and the carbon aerogel had good dispersion as a carrier for ZnS to solve the ZnS agglomeration problem. The morphology and structure of C@zeolite-ZnS were characterized by FT-IR, XRD, SEM, BET, and XPS. C@zeolite-ZnS showed excellent selectivity and high removal rate for Hg(II) ions with a maximum adsorption capacity of 795.83 mg/g. When the pH, adsorption time, and Hg(II) ion concentration were 6, 30 min, and 25 mg/L at 298 K, the corresponding adsorption and removal rates reached 99.90% and 124.88 mg/g, respectively. Thermodynamic studies have shown that the adsorption process is a spontaneous heat absorption process. Furthermore, after up to 10 cycles of adsorption, the adsorbent still exhibited outstanding stability and high adsorption capacity with removal rates exceeding 99%. In conclusion, C@zeolite-ZnS, which is stable and reusable and has the ability to meet industrial emission standards after adsorption of Hg(II) ions, is very promising for industrial applications.

Synthesis, Characterization of NaA Zeolite from Blast Furnace Slag (BFS) via Alkaline Fusion and Hydrothermal Treatment

Synthesis, Characterization of NaA Zeolite from Blast Furnace Slag (BFS) via Alkaline Fusion and Hydrothermal Treatment

Synthesis, Evaluation, Modeling and Simulation of Nano-Pore NAA Zeolite Membranes

Synthesis, Evaluation, Modeling and Simulation of Nano-Pore NAA Zeolite Membranes

Metakaolin-based geopolymer – Zeolite NaA composites as CO2 adsorbents

In this work, three metakaolin-based geopolymer matrices were prepared, varying the molar ratio Si:Al (2.0 or 1.2) and the type of cation (sodium or potassium). Starting from these matrices, geopolymer-zeolite composites were synthesized and consolidated (80 °C), incorporating a commercial sodium-based zeolite, Na4A, with the aim of producing post combustion CO2 adsorbents, since the presence of Na4A crystalline phase is desirable due to its known remarkable CO2 adsorption capacity.The sodium-based geopolymer matrix with Si:Al = 1.2 allowed the in situ nucleation of the zeolite NaA, therefore this matrix was added with different amount of synthetic zeolite Na4A to verify the total conversion of the matrix into zeolite NaA, in view of an alternative low-cost synthesis method to obtain zeolite NaA as a “solid” in a complex form.The composites were deeply characterized and lastly tested for CO2 adsorption. The geopolymer matrices act as binders allowing the shaping of zeolite and producing functional composites with mutable chemical composition, microstructure and porosity according to the starting composition. The sodium-based geopolymer zeolite composite was the best performing in term of CO2 adsorption capacity being 1.0 mmol g−1 at 0.1 bar, nearly equivalent to synthetic zeolite Na4A (1.2 mmol g−1) and close to pure zeolite Na13X (1.4 mmol g−1), the current benchmark material for carbon capture application.

Comparison of NaX and NaA Zeolites as Absorbents in Purification Units of Pure Kr and Xe Production Plants

Comparison of NaX and NaA Zeolites as Absorbents in Purification Units of Pure Kr and Xe Production Plants

Separation of cobalt and lithium from spent LiCoO2 batteries using zeolite NaA and the resulting ion exchange product for N2/O2 separation

As a common material used in lithium-ion batteries, LiCoO2 has both environmental and economic benefits due to its recyclability (key metals: Co and Li). Hydrometallurgy, a common method used to recover metal ions, is still facing challenges in terms of the effective and simple recovery of metal ions from the leaching solution. In this work, a new method of separating Co2+ and Li+ from the leaching solution of spent LiCoO2 using zeolite has been proposed. As a result, NaA zeolite exhibited the highest Co2+/Li+ separation selectivity in the Co-Li (1:1) mixed solution, reaching > 95% Co2+ removal, while all Li+ remained in the solution. In addition, CoNaA, a product separated from the Co-Li mixed solution by NaA zeolite, has been tested for its N2 and O2 adsorption properties; the N2/O2 selectivity (80/20, v/v) was up to 5.3 and the breakthrough experiment results demonstrated its excellent N2/O2 separation performance. Overall, ion exchange using NaA zeolite is a promising method used to separate Co2+ and Li+ from a LiCoO2 leaching solution and the exchange products can be used as an adsorbent for N2/O2 separation.

Synthesis of composite zeolite membrane by low-temperature water bath for efficient dynamic hardwater softening

In recent years, zeolite membrane has developed rapidly in the application of water treatment technology. However, the traditional zeolite membrane preparation process has the shortcomings of high temperature hydrothermal and other complex processes, which hinder its potential for large-scale industrial applications. In this study, a metakaolin/slag composite NaA zeolite membrane (GNaAM-20) on stainless steel substrate was prepared by composite geopolymer (metakaolin mixed with 20% slag) in a low-temperature water bath method, and GNaAM-20 was applied to the dynamic separation of Ca2+ from hard water. In this work, the mechanical strength (10.08 MPa) and crystallinity (92.13%) of composite zeolite membrane were enhanced by adjusting the slag content, so that a compact and higher removal efficiency zeolite membrane was prepared. The results showed that the GNaAM-20 had excellent acid resistance (pH = 1) with a removal efficiency of 92.03%, and the Ca2+ average removal efficiency by dynamic filtration after ten times of filtration (500 mL per filtration) was 91.2% using a 500 mg·L−1 Ca2+ solution. The maximum dynamic membrane adsorption capacity of GNaAM-20 was 102.54 mg·g−1. Compared with powder or gel adsorbents. GNaAM-20 virtually maintained its initial removal abilities after 5 regeneration cycles (average removal rate of more than 95%), and it had more significant advantages in terms of recycling and regeneration. Therefore, this study provides new ideas for achieving hard water softening and provides scientific guidance for industrial production.

Low-cost and high-stability superhydrophilic/underwater superoleophobic NaA zeolite/copper mesh composite membranes for oil/water separation

The development of functional membranes with easy operation, low cost, high stability, and large flux is urgently required for the effective treatment of increasing oily wastewater. In this work, using low-cost, readily available, and “green” metakaolin as the main raw material, NaA zeolite/copper mesh composite membranes (NaA@CM) for oil/water separation were newly prepared by a one-step hydrothermal method. The hydrothermal temperature was found to have an important effect on the structure and properties of NaA@CM. The composite membrane prepared at 110°C (NaA@CM-110) was covered by a large number of in situ generated crystalline NaA zeolite and thus exhibited optimum underwater superoleophobicity (underwater oil contact angle 151.3°), large water flux (10114 L m−2 h−1), and the highest separation efficiency (98.6%) for the cyclohexane/water mixture. Moreover, in a continuous oil/water separation process, NaA@CM-110 showed comparable separation efficiency for different oily wastewaters, with good self-cleaning properties, friction resistance, recyclability, and chemical stability even under harsh conditions. In general, NaA@CM-110 is not only low cost, simple process and environmentally friendly, but also has broad prospects in practical oil/water separation.

Influences of crystallization time, batch molar ratios Al2O3/SiO2 and Na2O/SiO2 on particulate properties of sodalite crystals prepared under room-temperature conditions

Sodalite crystals were prepared by the hydrothermal method under room-temperature conditions. The influences of crystallization time, batch molar ratios Al2O3/SiO2 and Na2O/SiO2 on the crystalline end products were investigated. For comparison, an experiment was also carried out in which sodalite was synthesized at 90 °C for 10 h. The results revealed that with the prolongation of crystallization time from 1 h to 14 days, the crystallization followed a sequence of phase transformations from an amorphous phase to zeolite NaA, and finally to sodalite. Spherical sodalite crystals composed of very small crystallites were obtained after 10 h of room-temperature crystallization. Whereas, with the same gel composition, the sodalite synthesized at 90 °C for 10 h was large lepispherical particles. High Al2O3/SiO2 molar ratio favored the generation of smaller individual sodalite nanocrystals, which resulted in the formation of larger steady congregated agglomerates. Moreover, alkalinity circumstance determined whether or not sodalite was formed. Well-developed cubic zeolite NaA particles were obtained at Na2O/SiO2 = 1.4; when the Na2O/SiO2 was increased to 8.0, zeolite NaZ-21 crystals were generated, meanwhile, the decomposition of wool ball-like sodalite particles into nanorods was also observed.

Hybrid Na-A zeolite/oxycut residue thin film composite nanofiltration membrane for Cr (III) removal

An alternative approach to fabricating a thin-film composite (TFC) nanofiltration membrane by incorporating industrial residues is reported in this study. Na-A zeolite was synthesized from coal fly ash by alkali fusion and hydrothermal treatment to be added into a polyethersulfone (PES) support via phase inversion. A thin polyamide layer was created on the PES support by interfacial polymerization from a blend of the prepared Na-A zeolite and oxycut powder, a novel and unexplored carbon steel residue. The effect of the modified membrane was evaluated through scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and water contact angle measurements. The synthesized Na-A zeolite and oxycut powder were characterized via X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), BET surface area, and leaching tests. The residues’ suitability as membrane fillers was first determined by their adsorption capacities of Cr (III) ions, achieving 21.17 mg/g for Na-A zeolite and 24.88 mg/g for the oxycut. Experimental data were reliably fitted by Freundlich adsorption isotherms. The hybrid membrane’s performance exhibited 98% of Cr (III) ions removal in a crossflow setup with two membranes in series. Considering the nature of the wastes, the leaching of other pollutants was monitored throughout the experimentation; the results exhibited no presence of toxic elements in the permeate, proving the promising applicability of these residues.

Zeolite Na-A supported TiO2: Effects of TiO2 loading on structural, optical and adsorption properties

Zeolite Na-A supported TiO2 nanopowders were synthesized via a modified sol–gel technique and the effects of TiO2 loading were characterized for thermal, structural, morphological, optical and textural behaviour. Thermal properties predicted a minimum annealing temperature of 600 °C whereas the X-ray diffraction (XRD) patterns indicated that the composite was highly crystalline, and consisted of both TiO2 and zeolite Na-A peaks. Scanning electron microscopy (SEM) images confirmed that the TiO2 nanoparticles occurred mainly on the surface of the zeolite Na-A support. Nitrogen adsorption–desorption studies portrayed increased porosity and larger surface area for TiO2/zeolite Na-A compared to pure TiO2. The optical band gap decreased with increased TiO2 loading from 3.17 to 2.85 eV. The synthesized nanopowders were applied in photocatalytic dye removal, where by the highest degradation rate for the supported TiO2 was realized at 1.5 %TiO2/zeolite Na-A loading. It was found that loading beyond 1.5 %TiO2 led to a structural collapse and decline in the photodegradation rate.

Synthesis of NaA zeolite from foundry dust and its adsorption capacity of ammonia

Eutrophication of water bodies due to excess ammonia nitrogen (NH4+-N) is harmful to aquatic organisms and human health. In this study, foundry dust (FD) from foundry industry was used to synthesize NaA zeolite to use as an adsorbent to remove NH4+-N from wastewater. Results demonstrate that FD could be successfully synthesized to form a foundry dust-based NaA zeolite (FZA) through adjustment of the silica-alumina ratio of n (SiO2)/n (Al2O3) at 2 at 95 °C. Specific surface area, total pore volume, and cation exchange capacity (CEC), and maximum adsorption NH4+-N of FZA was respectively 43.185 cm2/g, 0.0364 cm3/g, 212.35 mmol/100 g and 37.81 mg/g, which was 4.74, 1.54, 1.52 and 1.62 times as much as the NaA zeolite (SZA). FZA with higher adsorption NH4+-N capacity was related to higher specific surface area and CEC. The NH4+-N adsorption amount of 28.57 mg/g by FZA was obtained after the fourth regeneration, which was notably higher than that of SZA (23.27 mg/g). The desorption rate of NH4+-N from FZA was 87% by the fourth regeneration. FZA effectively removed NH4+-N from swine wastewater containing 153.32 mg/L NH4+-N. Results suggest that FZA could be used as absorbent to removal NH4+-N from wastewater.

Preparation of NaA and NaY zeolites from kaolin and their use as adsorbent for the removal of Ni2+ and Co2+ in aqueous solution

Heavy metal ions can cause environmental problems and affect human health if they are not properly removed before waste water released into the environment. Adsorption is one of the most widely used method for removal of heavy metal ions due to its simplicity and efficiency. Among many adsorbents, NaA and NaY zeolites showed good ability to remove metal ions in aqueous solution due to their high ion exchange capacity. However, the cost of zeolites NaA and NaY, synthesized from pure chemical sources, is still quite high. Therefore, this paper presented the synthesis of NaA and NaY from kaolin, a commercial available and cheap material. Experimental results showed that kaolin calcined at 500°C was appropriate to be used as and source for synthesis of zeolite. NaA and NaY zeolites were synthesized by reaction at 100°C in 24 hours. NaA zeolite was synthesized in a gel with the molar ratio in term of 1.0 Al2O3/2.0 SiO2/1.6 Na2O/76 H2O and NaY zeolite was synthesized with the molar ratio of 1.0 Al2O3/3.7 SiO2/2.7 Na2O/76 H2O with the addition of from industrial fly ash. XRD results of both synthesized NaA and NaY zeolites showed that the diffraction peaks of these zeolites matched with simulated XRD pattern of NaA and NaY zeolite. Synthesized NaA and NaY zeolites were used as adsorbents to remove Ni2+ and Co2+ in aqueous solution. NaY zeolite showed the highest adsorption capacity of 56.5 mg/g and 58.2 mg/g for Ni2+ and Co2+, respectively. NaA zeolite showed higher metal removal efficiency than that of NaY zeolite, with the highest adsorption capacity for Ni2+ and Co2+ at 80 mg/g and 123.2 mg/g, respectively. Experimental data fit the pseudo-second-order model and Langmuir isotherm adsorption model well. The results showed that the removal of Ni2+ and Co2+ ions by NaA and NaY zeolites was of the .

Mechanism of H2O Vapor Adsorption in A Type Zeolites: A Model Based on Adsorption Calorimetry

In this study, the energy characteristics of water vapor adsorption in NaA and NaA(NaBO2) zeolites were measured by adsorption calorimetry. Information of differential heats, isotherms, entropy and kinetic of adsorption in the matrix of NaA and NaA(NaBO2) zeolites were obtained. Adsorption isotherms (a) and differential heats of adsorption (Qd) of water vapor by NaA and NaA(NaBO2) zeolites were measured at 303 K. The heats of adsorption are stepwise and each step corresponds to the stoichiometric formation of adsorption complexes of H2O molecules with Na+ or H+ ions, (H2O)n/Na+ or H+, (n = 1-4), which are located on the SIII, SII and SI crystallographic positions of NaA and NaA(NaBO2). Hydration mechanism of NaA and NaA(NaBO2) are complex and at saturation, the zeolites are occupied by the next water zeolitic host/guest systems: NaA – 2.2[(H2O)4/Na+III+H+], 3[(H2O)2/Na+II] and 6.6[(H2O)2/Na+I]; NaA(NaBO2) - 2[(H2O)4/Na+III], 3[(H2O)4/Na+II] and 6.86[(H2O)/Na+I]. The complete hydration of the α- and β cages of NaA amounts thus to 21,8 and 6,2 respectively H2O/u.c. and α-cage of NaA(NaBO2) – 26,3 H2O/u.c. The mean molar integral adsorption entropy of water is ~-30,5 J/mol K less than the entropy of the bulk liquid. This value nearly the same as entropy of crystalline water so the mobility of water in the zeolitic matrix is solidlike.

Thermodynamics of Carbon (IV)-Oxide adsorption on NaA Zeolite obtained by modification of angren kaolin

Purification of natural gas from carbon dioxide is extremely important for the gas processing industry of Uzbekistan. Type A zeolites are the most suitable for this purpose. The patterns of water adsorption in the NaA zeolite have been considered. It was found that an appreciable amount of water is adsorbed in β-cavities. The carbon dioxide molecule is somewhat larger than the water molecule and, therefore, at room temperature it is unable to penetrate into the β-cavities through the six-membered oxygen windows of 2.6 Å diameter and form there ion-molecule clusters with sodium cations. However, the cations themselves can migrate from the β-cavities to the α-cavities under the influence of adsorbing molecules.

Nano NaA thick film: Excellent EG vapors sensor

The aim of the present research is to use a thick film of Nano Sodium A Zeolite (NaA) sensors to detect ethylene glycol vapours (EG). The obtained NaA zeolite material was characterised using XRD, FTIR, SEM-EDS, and TG-DTA analysis to investigate its physicochemical properties. The screen printing technique was used to deposit NaA thick films on glass substrates. NaA sensors have been found to be sensitive to EG. The sensors were revealed to functional operating temperature at 95 °C, with fast response and recovery times of 90 s, respectively. EG vapours with concentrations ranging from 2 to 90 ppm can be detected by the sensors. According to the findings, NaA zeolite could be used as a potential method for identifying EG vapours..

Colloidal Stabilization of Submicron-Sized Zeolite NaA in Ethanol-Water Mixtures for Nanostructuring into Thin Films and Nanofibers.

Despite the growing use of organic or mixed solvents in zeolite processing, most studies focus only on aqueous suspension systems. We investigated the colloidal characteristics of submicron-sized zeolite NaA in mixed ethanol-water solvents. The effects of the mixing ratio of solvents and various additives on the dispersion of the zeolite powders were studied. The zeolite NaA particles were destabilized in solvent mixtures at a high ethanol-to-water ratio, a reduction in the zeta potential was observed, and the destabilization was rationalized by the Derjaguin, Landau, Verwey, Overbeek (DLVO) theory. An improved stabilization of the zeolite NaA suspensions was achieved in ethanol-rich solvent mixtures using nonionic low molecular weight organic additives, but not with their ionic counterparts such as anionic, cationic surfactants or inorganic acids or bases. Polyethylene glycol (PEG)-400 was found to be a good dispersant for the submicron-sized zeolite NaA particles in the ethanol-water mixtures, which was attributed to its interaction with the zeolite surface, leading to an increased zeta potential. The PEG-stabilized zeolite suspensions led to low suspension viscosities as well as uniform and consistent spin-coated films.

Synthesis, Evaluation, Modeling and Simulation of Nano-Pore NAA Zeolite Membranes

Synthesis, Evaluation, Modeling and Simulation of Nano-Pore NAA Zeolite Membranes