Cancrinite Zeolite Research Articles

Unlocking the potential of phosphogypsum waste: Unified synthesis of functional metal-organic frameworks and zeolite via a sustainable valorization route

Phosphogypsum (PG) is one of the hazardous wastes generated during phosphate fertilizers production. Valorizing PG into value-added materials is needed to overcome the environmental threat of accumulating PG stockpiles. The primary chemical constituents of PG are CaSO4·2H2O, SiO2, Al2O3, P2O5, and trace metals. Herein, we employed unified strategic synthesis method to transform the main components of PG into two classes of functional porous materials in subsequent steps. The alumina and silica components were isolated to fabricate cancrinite zeolite (CAN) while the residual calcium was directed to grow Ca-based metal–organic frameworks (Ca-MOFs) in the subsequent step. The resulting zeolite with a Si/Al ratio of ∼2.2 showed enhanced CO2 capture property, which, in many respects, is better than those achieved by similar frameworks from other precursors. The unveiled MOF synthesis approach was proven to be adaptable, allowing the preparation of different Ca-MOFs from organic linkers of diverse connectivity, namely Ca-BDC, Ca-BTC, and Ca-TCPB (SBMOF-2), using the linear ditopic benzene dicarboxylate, the tritopic benzene tricarboxylate, and tetracarboxylate-based linkers, respectively. The successful assembly of the porous materials was confirmed using various characterization techniques, including XRD, SEM-EDX, FTIR, and TGA-MS. The porosity of the materials was also probed using N2 at 77 K, CO2 at different temperatures, and H2O at 298 K sorption analyses. The Ca-BTC MOF with the optimal pore aperture size (∼3.4 Å) shows a potential for water/alcohol separation with a steep and fast moisture adsorption profile and negligible alcohol uptake. The synthetic transformation approach presented in this work represents the first example of a valorization route to form extended porous structures from PG waste.

Swift Removal of the Heavy Metals Cadmium and Lead from an Aqueous Solution by a CAN-Zeolite Synthesized from Natural Clay

CAN-zeolite was synthesized with a high purity from natural kaolinite via alkali fusion by hydrothermal treatment at a pressure of 1 kbar H2O. It was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), infrared spectroscopy and nitrogen adsorption at 77 K. The results show that after AK hydrothermal treatment (under specific conditions), the SBET increases from 5.8 m2g−1 to 30.07 m2g−1 which is six times greater. The AK which was a non-porous or macroporous solid (the nitrogen adsorption/desorption of AK is of type II) became mesoporous (N2 adsorption–desorption isotherms exhibit typical hysteresis of type IV) with a pore size of 5.9 Å. XRD of AK shows the presence of quartz (Q) as impurities, and illite and kaolinite as major fractions; after hydrothermal treatment, the XRD diffractogram shows only fine pics related to CAN-zeolite (with a good crystallinity), confirming the success of the synthesized process. These results suggest that the synthesized CAN-zeolite has the potential to be tested in the removal of heavy metals from waste water as part of a remediation process. Batch reactors were used to evaluate the adsorption isotherms and kinetic studies of heavy metals, cadmium, and lead, by natural kaolinite clay (AK) and synthesized cancrinite zeolite (CAN-zeolite). The results show that the adsorption kinetics of the bivalent heavy metals cadmium and lead are extremely fast with either AK or CAN-zeolite. Equilibrium was reached within 2 min. Adsorption isotherms show that the synthesized CAN-zeolite has a higher adsorption capacity; the retention capacity of lead and cadmium was three times greater than that presented by the natural clay mineral. According to the findings, CAN-zeolite has a higher affinity for PbII (192 mg/g) compared to CdII (68 mg/g). The negative reactive surface sites interacting with these cationic heavy metals resulted in a higher amount of heavy metals adsorption than the cation exchange capacity (CEC). The adsorption information was analyzed using the Langmuir and Freundlich equations. The Langmuir model provided a good fit to the equilibrium data, indicating a monolayer adsorption mechanism.

Transforming industrial solid wastes into eco-friendly zeolite material for efficient heavy metal ion stabilization through host-guest combination

In this work, the “host-guest” combination has been conducted upon the utilization of dual industrial solid wastes, namely, spent FCC catalyst and red mud. The host of cancrinite zeolite was successfully synthesized under the optimum conditions of pre-treatment temperature of 500 °C for 4 h, spent FCC catalyst to NaOH of 0.8 (mass ratio), nitric acid to red mud of 5 (volume/mass), 140 °C for 12 h. The as-synthesized cancrinite sample had the maximum specific surface area of 251 m2/g, resulting in the relative leachability for Ni2+ (0.03%) and V2+ (0.38%) much better than that of spent FCC catalyst. The “host-guest” rule was discussed to reveal the mechanism for heavy metal ions stabilized into cancrinite zeolite. The feasibility (sources, synthesis methods, energy consumption and performance) of the present study was evaluated on a medium level by comparison with other literatures. Finally, the cost assessment of cancrinite zeolite was checked and the production cost was about 8 $/kg, decreasing the production price by at least 95% compared to commercial zeolites. Thus, the present study showed the feasibility and potential of solid wastes for stabilizing heavy metal ions, particularly in an advantage of the cost-effectiveness.

Removal of Fe<sup>2+</sup> and Mn<sup>2+</sup> from Water by Using Mining Rock Wastes and Their Synthesized Zeolites

The process of using mining rock waste as raw material to synthesis zeolite species is a viable alternative. Such process is minimizing serious impact of mining wastes on the environment and solving environmental problems such as water purification. In the present study, faujasite (NaX) and sodalite – cancrinite (sod-can) zeolites were successfully synthesized by hydrothermal crystallization using green siltstone, mudstone and black shale of mining rock wastes from Abu Tartur phosphate mine, western desert, Egypt. The raw materials as well as synthesized zeolites were characterized by means of X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), Thermogravimetry (TG), Differential Thermal Analysis (DTA) and Brunauer–Emmett–Teller (BET). Raw material (black shale) and synthesized zeolites (Na-X) faujasite were examined as heavy metal (Fe and Mn) adsorbent from aqueous solution. The results show that Na-X faujasite is very faster and higher in the up taking of Fe²⁺ and Mn²⁺ ions relative to the black shale absorbent or even the synthesized sodalite-cancrinite. Fe²⁺ and Mn²⁺ adsorption onto black shale absorbent and synthesized faujasite followed Langmuir isotherm, however, Freundlich isotherm model is accepted in the case of sodalite-cancrinite adsorbent. The adsorption kinetics of Fe²⁺ and Mn²⁺ onto the studied samples follow pseudo-second order model indicating chemical interaction (chemisorption) adsorption process.

Facile and fast synthesis of cancrinite-type zeolite from coal fly ash by a novel hot stuffy route

Coal fly ash (CFA) is an industrial solid waste discharged from coal-fired power plants. Due to the high contents of aluminum and silicon, it can be direct used for synthesis of zeolites. In this study, cancrinite (CAN) type zeolite was prepared from CFA by a novel hot stuffy method. The effects of various parameters such as alkaline dosage, crystallization temperature and holding time on the formation of zeolite were studied systematically. A well-crystallized CAN type zeolite was synthesized after mixing CFA with NaOH in a mortar followed by hot stuffy at 140 °C for 4 h. The characterized results revealed that the CAN zeolite showed a solo mineral phase with typical porous surface and internal ring structure. The synthesized zeolite was used as an adsorbent to remove anionic acid from aqueous solution, exhibiting great adsorption performance with 98 % removal efficiency within 40 min. This study provided a facile alternative for efficient utilization of solid waste to produce high value-added zeolite, exhibiting great potential for industrial application.

Scalable solvent-free synthesis of aggregated nanosized single-phase cancrinite zeolite

Pure cancrinite zeolite was prepared using a solvent-free method from a geophagic clay. The morphology of the zeolite could be controlled through the composition of the raw mixture. Aluminum sulfate octadecahydrate was used for the first time as a source of trace water in the solvent-free synthesis of a zeolite. Aggregated nanosized single-phase cancrinite zeolite were prepared using a mixture of the clay, aluminum sulfate octadecahydrate and sodium hydroxide. The mixture was manually mixed and heated at 150 °C for 6 h. Scaling up the synthesis to 2, 4 and 8 times resulted in products with remarkably consistent textural characteristics. The cancrinite prepared showed potential for use as a low-cost adsorbent for CO2 capture at very low CO2 concentrations.

Synthesis of novel hierarchical porous zeolitization ceramsite from industrial waste as efficient adsorbent for separation of ammonia nitrogen

In this study, a green process of high temperature sintering activation + hydrothermal reaction for the synthesis of novel zeolitization ceramsite from industrial wastes was designed. The synthesis process of zeolitization ceramsite was studied by XRD, SEM and FT-IR. The adsorption process of ceramsite was described by experiments and various kinetic model and isothermal adsorption model. The results show that the optimum preparation conditions were as follows: sintering temperature at 1040 ℃, hydrothermal temperature at 160 ℃, NaOH concentration of 3 mol/L and time of 12 h. XRD and FT-IR showed that the modified ceramsite was loaded with cancrinite zeolite crystals, which was the main reason for the increase of specific surface area from 1.259 m2/g to 17.92 m2/g. Furthermore, the adsorption capacity of ammonia nitrogen increased from 2.02 mg/g to 19.9 mg/g. The adsorption mechanism of ammonia nitrogen by ceramsite was mainly ion exchange, which also accords with the structural characteristics of zeolite. The results are highly attractive for many industrial applications due to the simplicity and green of the synthesis procedure and remarkable adsorption properties.

Rapid Zeolization of Potassic Rocks by Means of a Microwave‐Assisted Hydrothermal Method

AbstractPotassic rocks are rapidly activated and converted to cancrinite (CAN) zeolites in NaOH solution via microwave‐assisted hydrothermal (MH) method. The conditions of zeolization process via MH method are optimized, and the mechanism is illustrated. The phase transition process of potassic rocks is obtained as follows: decomposition of the potassic rocks→zeolite sodalite→zeolite CAN. In this process, the microwave exerts a reinforcement effect by generating the cleavage cracks on the surface of potassic rocks and accelerating the dissolution and crystallization processes. The synthesized zeolite CAN exhibits the maximum adsorption capacity of 6.5 mg g−1 for methylene blue. In addition, the filtrate is further used to prepare linda type A (LTA) zeolites by conventional hydrothermal synthesis method. The synthesized zeolite LTA presents the cubic morphology with rounded corners, and its Ca2+ ion exchange capacity could reach 335.6 mg CaCO3 g−1.

Converting loess into zeolite for heavy metal polluted soil remediation based on “soil for soil-remediation” strategy

Both soil erosion and soil contamination pose critical environmental threats to the Chinese Loess Plateau (CLP). Green, efficient and feasible remediation technologies are highly demanded to meet these challenges. Herein we propose a unique “soil for soil-remediation” strategy to remediate the heavy metal polluted soil in CLP by converting loess into zeolite for the first time. With a simple template-free route, the natural loess can be converted into cancrinite (CAN) type of zeolite. A highly crystalline CAN was obtained via hydrothermal treatment at 240 oC for 48 h, with a precursor alkalinity of Na/(Si+Al)> 2.0. The as-synthesized CAN zeolite exhibits excellent remediation performance for Pb(II) and Cu(II) polluted soil. Plant assay experiment demonstrates that CAN can significantly restrain the uptake and accumulation of Pb(II) and Cu(II) ions in vegetables, with a high removal efficiency up to 90.7% and 81.4%, respectively. This work demonstrates a “soil for soil-remediation” strategy to utilize the natural loess for soil remediation in CLP, which paves the way for developing green and sustainable remediation eco-materials with local loess as raw materials.

The chicken eggshell calcium oxide ultrasonically dispersed over lignite coal fly ash-based cancrinite zeolite support as a catalyst for biodiesel production

Lignite coal fly ash (FA) from a domestic thermal power plant was converted into a pure cancrinite zeolitic material (ZMFA) using a novel, custom-made, rotating autoclave reactor system by a short-term alkali activation process. The obtained ZMFA was used as catalyst support of calcium oxide as an active component derived from waste chicken eggshells (ES). The ZMFA supported calcium oxide catalyst (xCaO/ZMFA) was synthesized by means of the ultrasound-assisted method. The influence of different concentrations of dispersed calcium oxide (x = 5–20 wt%) over ZMFA and thermal treatment at different temperatures (450–600 °C) were studied. The structural and morphological characterization showed that the original cancrinite structure was preserved. The basicity and textural properties indicated the presence of strong active sites in a well-defined pore network suitable for the reactions of bulky organic compounds such as triacylglycerols (TAGs). The highest activity (96.5% of fatty acid methyl esters) in the methanolysis of sunflower oil was achieved with the 20CaO/ZMFA catalyst under reaction conditions: temperature of 60 °C, methanol/oil molar ratio of 12:1, catalyst concentration of 4 wt%, and reaction time of 2 h. It was found that the optimal calcination temperature of the catalyst precursor was 550 °C. At calcination temperatures above 550 °C, the melting of the glassy phase became more intense whereby the molten phase partially reacted with calcium oxide forming the catalytically inactive calcium silicate compounds (wollastonite, larnite, etc.). The rate constants of the two tested kinetic models were correlated with the concentrations of active calcium oxide. The MRPD of both models was low indicating their reliability.

Synthesis of magnetic zeolites from recycled fly ash for adsorption of methylene blue

Coal fly ash (CFA) was obtained from the Sochagota TermoPaipa IV power plant in Boyacá Colombia. CFA was subjected to a hydrothermal activation with NaOH. Morphology, elemental and mineralogical composition and magnetic properties of the obtained products were studied by means of SEM-EDX, XRD and VSM.Activation with NaOH (4–5 M) between 80 and 150 °C for 24 h produced cancrinite zeolite; activation with NaOH at 2 and 3 M at 95 °C produced analcime zeolite. It was found out, that the synthesized zeolites exhibit a ferrimagnetic behavior due to iron coming from CFA. The magnetic response of the obtained products allows the use of these materials to environmental applications in aqueous medium. Adsorption test for methylene blue was performed for an analcime and cancrinite zeolite, the results show that equilibrium is reached after 60 min. The data of adsorption isotherms for analcime and cancrinite zeolite were fitted to Freundlich and Langmuir model, respectively. The synthesized zeolites from CFA were successfully used to remove methylene blue from aqueous solution.

Solvent‐Free Synthesis of 1D Cancrinite Zeolite for Unexpectedly Improved Gasoline Selectivity

AbstractZeolites as a kind of representative solid acid material, owning unique microporous channels, could be proposed as reasonable candidate muti‐funcational catalysts on oriented synthesis of target products from syngas. This paper represents a novel way for the synthesis of cancrinite zeolite (CAN‐topology) using a solvent‐free strategy. Thus prepared CAN zeolite loaded Co‐based catalyst exhibited a remarkable catalytic performance for direct gasoline synthesis from syngas, producing unexpected gasoline selectivity with 78.3%. The amazing result was attributed to CAN zeolite with a straight channel (12MR, 1‐dimension), leading that Fischer‐Tropsch primary products could continuously and quickly diffuse in its channels. Moreover, a lack of shape selective behavior and weak acidity on CAN zeolite exhibited low isoparaffin selectivity. The Na+ content in CAN zeolite was also an important factor for tuning the product distribution. As expected, the green and facile solvent‐free approach for constructed CAN zeolite will play a vital application in selective conversion of syngas in the future.

A simple synthesis of nitrate cancrinite from natural bentonite

A nearly pure, pale brown, spherical, nitrate cancrinite zeolite was successfully synthesized from natural bentonite as starting material with acidic activation treatment via hydrothermal method at 368 K for 24 h. The effect of different NaOH concentrations (pH at around 12) was investigated without addition of silica and aluminum sources. The effect of different NaOH concentrations (pH at around 12) was investigated without addition of silica and aluminum sources. The final products were characterized by powder X-ray diffraction, scanning electron microscopy, elemental and thermal analyses, infrared (IR) spectroscopy, and Brunauer–Emmett–Teller (BET) surface area measurements. While the Si/Al ratio of ideal cancrinite is 1.0, the Si/Al ratio of the product framework is approximately 1.76, apart from trace components. Unique single nitrate band was observed in both IR and thermogravimetric measurements, indicating that pure cancrinite was synthesized. This study showed that pure nitrate cancrinite was obtained with NaOH concentrations from 8 to 12 M, independent of NaOH contents on crystallization. Through this study, we proposed a simple synthesis method for pure nitrate cancrinite from bentonite for the purpose of recycling natural clay minerals.

Template-free synthesis and structural evolution of discrete hydroxycancrinite zeolite nanorods from high-concentration hydrogels.

We report the synthesis and characterization of hydroxycancrinite zeolite nanorods by a simple hydrothermal treatment of aluminosilicate hydrogels at high concentrations of precursors without the use of structure-directing agents. Transmission electron microscopy (TEM) analysis reveals that cancrinite nanorods, with lengths of 200-800 nm and diameters of 30-50 nm, exhibit a hexagonal morphology and are elongated along the crystallographic c direction. The powder X-ray diffraction (PXRD), Fourier transform infrared (FT-IR) and TEM studies revealed sequential events of hydrogel formation, the formation of aggregated sodalite nuclei, the conversion of sodalite to cancrinite and finally the growth of cancrinite nanorods into discrete particles. The aqueous dispersion of the discrete nanorods displays a good stability between pH 6-12 with the zeta potential no greater than -30 mV. The synthesis is unique in that the initial aggregated nanocrystals do not grow into microsized particles (aggregative growth) but into discrete nanorods. Our findings demonstrate an unconventional possibility that discrete zeolite nanocrystals could be produced from a concentrated hydrogel.

Potassium cation induced controllable synthesis of CAN zeolite hollow microspheres

A novelty hierarchical hollow nitrate cancrinite zeolite microspheres (HNCMs) with micro-plate crystals act as sphere shell and wrapped with large number of nanorods crystal in the center of the microspheres were synthesized by a simple organic-free hydrothermal synthesis methods. With the adjustment of potassium cation concentration in synthetic system, nitrate cancrinite zeolites realize morphology tunable architectures from nanorod to HNCMs. A systematic investigation of the crystal growth over different crystallization stages indicates a stepwise crystallization progress of HNCMs. First, the primitive nitrate cancrinite nanoplatelets self assembled to yield solid spherical clusters. Then the spherical clusters undergo a surface to core crystallization progress which was supposed to be the reason for the formation of hollow cores. This work provides an alternative strategy for the synthesis of spherical hollow zeolite materials with tunable architectures, which may potentially be used in the field of separation, catalysis and biomedicine.

Synthesis and properties of nanoparticle forms saponite clay, cancrinite zeolite and phase mixtures thereof

The low-temperature synthesis (90 °C) of nanoparticle forms of a pure phase smectic clay (saponite) and zeolite (cancrinite) is reported, along with phase mixtures thereof. A synthesis gel corresponding to the Si:Al:Mg unit cell composition of saponite (3.6:0.40:3.0) and a NaOH/Si ratio of 1.39 affords the pure phase clay with disordered nanolayer stacking. Progressive increases in the NaOH/Si ratio up to a value of 8.33 results in the co-crystallization of first garronite and then cancrinite zeolites with nanolath morphology. The resulting phase mixtures exhibit a compound particulate structure of intertwined saponite nanolayers and cancrinite nanolaths that cannot be formed through physical mixing of the pure phase end members. Under magnesium-free conditions, pure-phase cancrinite nanocrystals are formed. The Si/Al ratio of the reaction mixture affects the particle morphology as well as the chemical composition of the cancrinite zeolite. Ordinarily, cancrinite crystallizes with a Si/Al ratio of 1.0, but a silicon-rich form of the zeolite (Si/Al = 1.25) is crystallized at low temperature from a silica-rich synthesis gel, as evidenced by 29Si NMR spectroscopy and XEDS-TEM. Owing to the exceptionally high external surface areas of the pure phase clay (875 m 2/g) and zeolite end members (8.9–40 m 2/g), as well as their unique mixed phase composites (124–329 m 2/g), these synthetic derivatives are promising model nanoparticles for studies of the bioavailability of poly-aromatic hydrocarbons immobilized in silicate bearing sediments and soils.

Synthesis of ultrafine zeolites by dry-gel conversion without any organic additive

ZSM-5, mordenite, cancrinite and Y zeolites were successfully crystallized by the dry-gel conversion (DGC) without any organic additive (or template), in which the crystal particles of ZSM-5, mordenite and Y zeolite were well controlled in the range of ultrafine size. With a molar ratio of SiO 2/Al 2O 3 ≤40, the pure ZSM-5 zeolite was obtained at 170 °C at the Na 2O/SiO 2 molar ratio <0.2, but the pure mordenite was formed at 150 °C at the Na 2O/SiO 2 molar ratio >0.25. When the dry-gel with a composition of 5.0Na 2O:Al 2O 3:5.0SiO 2 was crystallized at 140 °C for 24 h, pure cancrinite phase was obtained. TEM images showed that thus-crystallized zeolites consisted of ultrafine particles ranging 35–150 nm for ZSM-5, 50–200 nm for mordenite and 120–200 nm for zeolite Y, respectively. Different from ZSM-5, mordenite and cancrinite zeolites, the DGC synthesis of Y zeolite required more water in the dry-gel before crystallization.

Interaction between antimicrobial drugs and antacid based on cancrinite-type zeolite

A carbonated–nitrated cancrinite-type zeolite was synthesized using zeolite X as silicon and aluminum source under strongly alkaline conditions (NaOH and Na 2CO 3). Additionally, a hydrotalcite-like compound of 0.20 Al/(Al + Mg) ratio with nitrate and carbonate anions into its interlayer was also synthesized. Both solids were characterized by means of techniques such as XRD, FT-IR and BET surface area. These techniques confirmed the presence of pure cancrinite-type zeolite and hydrotalcite, without the presence of collateral phases. These solids had been previously tested as antacid agents and determined their interaction with acidic solution of aspirin. The results showed that these solids could be used as effective antacid without any possible interaction between both drugs. Following with our studies, we determined a possible interaction among tetracycline molecules and our synthesized antacids. These studies were carried out by UV–visible analysis of the supernatants and FT-IR of the interacted solids with tetracycline solutions. Variable quantities of zeolites and hydrotalcites were weighed and placed in contact with aliquots of tetracycline acid solutions at 37 °C and under agitation for 1 h to simulate stomach conditions. The FT-IR studies did not show interaction between the tetracycline molecule and these solids, however, in the studied supernatants, it was possible to confirm the formation of complexes among the cations from the dissolved solids and the tetracycline molecule. These interactions, determined by UV–visible spectrometry, were higher when pH increased. Also, these interactions were superior in the hydrotalcite than in cancrinite zeolite due to a large number of species in solution (Al 3+ and Mg 2+). In spite of our results, we believe that it is possible to administer cancrinite–zeolites as antacid 1 h before administering drugs based on tetracycline. Additionally, these results could represent an important advance in the formulation of new broad range drugs for medical applications.

ChemInform Abstract: Electron Spin Resonance and Electron Spin Echo Spectroscopic Studies of Cu2+ Sites in Synthetic Cancrinite Zeolites.

AbstractCu2+ is introduced (ion exchange) into the synthetic cancrinite zeolites Na6Al6Si6O24·8 H2O (I) and Na6Al6Si6O24·CaCO3·8 H2O (II).

Electron spin resonance and electron spin echo spectroscopic studies of Cu2+ sites in synthetic cancrinite zeolites

Electron spin resonance (ESR) and electron spin echo modulation (ESEM) studies of Cu2+ sites introduced by ion exchange are reported in two types of synthetic cancrinite zeolites, one of them a more hydrated sample, Na6 Al6Si6O24•8H2O (denoted C1), and the other a less hydrated sample with entrained calcium carbonate, Na6Al6Si6O24•CaCO3•8H2O (denoted C2). ESR spectra reveal that C1 activated at 100 °C contains Cu2+ sites of tetrahedral symmetry with [Formula: see text] and [Formula: see text] while at a higher activation temperature of 400 °C Cu2+ sites with a different symmetry are produced corresponding to [Formula: see text] and [Formula: see text] C2 activated at 100 °C contains almost exclusively Cu2+ sites of trigonal symmetry with [Formula: see text] and [Formula: see text] Two- and three-pulse ESEM experiments at 4 K give 2D and 27Al modulation patterns that corroborate these ESR assignments. Possible locations of the Cu2+ sites in the C1 and C2 structures are proposed.