Nanoporous Zeolite Research Articles

Modified nanoporous zeolites on a biodegradable polymer film with excellent hydrophobicity, ethylene gas adsorption, and antibacterial activity through surface charge accumulation

The high specific surface area and large pore volume of nanoporous zeolites (NZs) were utilized to impart a biodegradable polymer film with superhydrophobicity, ethylene gas adsorption capability, and active antibacterial activity. NZs were synthesized by using organic silanes via a sol–gel method. They were then dispersed on a biodegradable blended PPP [poly(lactic acid) (PLA)/poly butylene succinate (PBS)/poly butylene adipate terephthalate (PBAT)] film to enhance its mechanical properties and control water repellent. The hydrophobicity of the organic silanes on the zeolite surface gradually increased according to their length. The film prepared by utilizing octadecyltriethoxysilane (ODTES) was superhydrophobic with a contact angle 142.6°. The porous structure of the PPP with attached ODTES-NZs impeded the release of accumulated charges generated through friction, thereby yielding excellent output voltage when applying friction periodically. The output performance of the PPP-ODTES-NZs film was measured to be 723 V when a positive charge was injected into the film, which was about 3.1 times higher than the output performance of the PPP film without surface modification. The accumulated positive charges provided excellent antibacterial efficacy against externally introduced bacteria. Our approach of attaching ODTES-NZs to a blended polymer provides a multifunctional biodegradable film (ethylene gas adsorption, water repellent, and antibacterial activity via positive charge accumulation) with excellent food-storage capability.

Realizing the Direct Synthesis of High Silica IWS Zeolite with Improved Hydrothermal Stability.

Direct synthesis of germanosilicate zeolites with low Ge content and improved hydrothermal stability is a great challenge. Herein, we successfully achieve the direct synthesis of IWS zeolite with a Si/Ge ratio higher than 4 for the first time. High silica IWS zeolites can be prepared in a wide range of Si/Ge ratios (4-16) by utilizing bulky 1,3-bis(1-adamantyl)-imidazolium (BAdaI+) as an efficient organic structure-directing agent from the concentrated synthesis gel under fluoride conditions. It is proven by a series of characterizations that Ge atoms preferentially occupy the double-four-ring (D4R) units. Theoretical calculations reveal the preferential interactions of guest organic structure-directing agents (OSDAs) and host IWS zeolites with different Si/Ge ratios. The introduction of more Ge atoms cannot improve the host-guest interaction when the BAdaI+ molecule is accommodated within the nanopores of IWS zeolite compared to other OSDAs. The obtained IWS zeolite shows an extremely high specific surface area (905 m2/g) and pore volume (1.31 cm3/g). Due to the low Ge content, IWS zeolite exhibits outstanding hydrothermal stability and experiences high temperature steam heating with no loss of crystallinity and only a slight loss of microporosity.

Nanoporous Zeolite UTL Decorated with Sn to Catalyze the Baeyer–Villiger Reaction

Nanoporous Zeolite UTL Decorated with Sn to Catalyze the Baeyer–Villiger Reaction

Learning a reactive potential for silica-water through uncertainty attribution

The reactivity of silicates in aqueous solution is relevant to various chemistries ranging from silicate minerals in geology, to the C-S-H phase in cement, nanoporous zeolite catalysts, or highly porous precipitated silica. While simulations of chemical reactions can provide insight at the molecular level, balancing accuracy and scale in reactive simulations in the condensed phase is a challenge. Here, we demonstrate how a machine-learning reactive interatomic potential trained on PaiNN architecture can accurately capture silicate-water reactivity. The model was trained on a dataset comprising 400,000 energies and forces of molecular clusters at the ωB97X-D3/def2-TZVP level. To ensure the robustness of the model, we introduce a general active learning strategy based on the attribution of the model uncertainty, that automatically isolates uncertain regions of bulk simulations to be calculated as small-sized clusters. The potential reproduces static and dynamic properties of liquid water and solid crystalline silicates, despite having been trained exclusively on cluster data. Furthermore, we utilize enhanced sampling simulations to recover the self-ionization reactivity of water accurately, and the acidity of silicate oligomers, and lastly study the silicate dimerization reaction in a water solution at neutral conditions and find that the reaction occurs through a flanking mechanism.

Synergistic Machine Learning Accelerated Discovery of Nanoporous Inorganic Crystals as Non-Absorbable Oral Drugs.

Machine learning (ML) has taken drug discovery to new heights, where effective ML training requires vast quantities of high-quality experimental data as input. Non-absorbable oral drugs (NODs) have unique safety advantage for chronic diseases due to their zero systemic exposure, but their empirical discovery is still time-consuming and costly. Here, a synergistic ML method, integrating small data-driven multi-layer unsupervised learning, in silico quantum-mechanical computations, and minimal wet-lab experiments is devised to identify the finest NODs from massive inorganic materials to achieve multi-objective function (high selectivity, large capacity, and stability). Based on this method, a NH4-form nanoporous zeolite with merlinoite (MER) framework (NH4-MER) is discovered for the treatment of hyperkalemia. In three different animal models, NH4-MER shows a superior safety and efficacy profile in reducing blood K+ without Na+ release, which is an unmet clinical need in chronic kidney disease and Gordon's syndrome. This work provides a synergistic ML method to accelerate the discovery of NODs and other shape-selective materials.

White-Light Emissive Silver-Exchanged Nanoporous NaP1 Zeolites

White-Light Emissive Silver-Exchanged Nanoporous NaP1 Zeolites

Zeolite A Thin Film Growth on Silica Optical Fibers

Thin films of zeolite A (Linde type A, LTA) were fabricated on silica optical fibers using dip coating method, followed by a secondary growth process. Zeolite A seed crystals with an average crystal size of 247.3 nm were synthesized through hydrothermal method. Then, the dip coating technique was applied to coat silica optical fibers. The one and two-time dip coating resulted in island-like growth, while three-time dip coating process led to the intergrowth of seed crystals, resulting in nearly continuous films on the optical fiber. The seed crystals, initially deposited as a monolayer, were grown by secondary growth method, leading to film thicknesses of 255.3 nm ± 10.1 nm (average ± standard deviation). Upon extending the secondary growth reaction time from 2 hours to 4 hours, the film thickness increased from 255.3 nm ± 10.1 nm to 649.6 nm ± 28.1 nm. Epitaxial growth was identified as the mechanism through which the seed crystals grow. The nanoporous zeolite A films formed on the optical fiber exhibit potential applications as gas sensors. These sensors function by detecting changes in optical reflection caused by the differential adsorption of gases.

Optical study of Te8 ring clusters: comparison with density functional theory and a step towards materials design using nanoporous zeolite space.

The Te8 ring molecule (cluster) is poorly investigated due to the lack of experimental data. Here, we report an experimental and theoretical study of a regular array of oriented Te8 rings formed in the ∼1.14 nm diameter cavities of zeolite LTA, which are arranged in a cubic lattice with a spacing of ∼1.2 nm. Single crystals of LTA with encapsulated tellurium (LTA-Te) were studied using Raman spectroscopy (RS) and optical absorption spectroscopy (OAS). The experimental LTA-Te spectra were found to be in agreement with those calculated using density functional theory (PBE0 hybrid functional and def2-TZVP basis sets) for the crown-shaped Te8 ring molecule with D4d symmetry. Using polarization-orientation RS, we show that the Te8 rings are oriented by their major axes along the 4-fold axes of cubic LTA. We also show that the site symmetry of Te8 in LTA-Te is lower than D4d. Te8 bond-bending modes are well described in the harmonic approximation, while bond-stretching modes are mixed due to the reduced ring symmetry and, probably, anharmonicity. Importantly, OAS data of LTA-Te display dependence on the Te8 concentration, implying the interaction of the rings from neighbouring LTA cavities with the generation of the valence and conduction electron bands of such a cluster crystal.

The mechanisms underlying Li+/Mg2+ separation in ZIF-8 under an electric field from atomistic simulations.

In this study, we explore the mass transfer and separation mechanism of Li+ and Mg2+ confined within the flexible nanoporous zeolite imidazolate framework ZIF-8 under the influence of an electric field, employing molecular dynamics simulation. Our results highlight that the electric field accelerates the dehydration process of ions and underscore the critical importance of ZIF-8 framework flexibility in determining the separation selectivity of the ZIF-8 membrane. The electric field is shown to diminish ion hydration in the confined space of ZIF-8, notably disrupting the orientation of water molecules in the first hydration shells of ions, leading to an asymmetrical ionic hydration structure characterized by the uniform alignment of water dipoles. Furthermore, despite the geometrical constraints imposed by the ZIF-8 framework, the electric field significantly enhances ionic mobility. Notably, the less stable hydration shell of Li+ facilitates its rapid, dehydration-induced transit through ZIF-8 nanopores, unlike Mg2+, whose stable hydration shell impedes dehydration. Further investigation into the structural characteristics of the six-ring windows traversed by Li+ and Mg2+ ions reveals distinct mechanisms of passage: for Mg2+ ions, significant window expansion is necessary, while for Li+ ions, the mechanism involves both window expansion and partial dehydration. These findings reveal the profound impact of the electric field and framework flexibility on the separation of Li+ and Mg2+, offering critical insights for the potential application of flexible nanoporous materials in the selective extraction of Li+ from salt-lake brine.

Mathematical modeling approach for the green synthesis of high-performance nanoporous zeolites Na-X optimized for water vapor sorption

A mathematical approach and green synthesis were employed to develop high-performance nanoporous zeolites with a high water vapor sorption capacity and to optimize the synthesis parameters using natural raw kaolin as the starting alumina-silicate material. The Box-Behnken design model with four factors was employed to elucidate the experimental matrix. The physicochemical and structural properties of the synthesized zeolite were characterized using XRD, FTIR, TG/DSC, 27Al and 29Si solid-state MSA NMR spectroscopy, Raman spectroscopy, FE-SEM, and N2 sorption isotherms. The obtained zeolite sample exhibited a BET surface area of 772.19 m2/g and a microspore volume of 0.16 cm3/g. The maximum water vapor uptake capacity at 25 °C and the highest relative pressure was determined to be 12.1137 mmol/g. The isosteric heat of adsorption and average entropy change were calculated to be − 41.340 KJ·K−1 and 115.308 J·mol−1·K−1, respectively. The resulting zeolite demonstrated excellent stability after five consecutive cycles of water vapor adsorption. The experimental data were fitted using five different isotherm and three kinetic models, and the accuracy of each model was assessed using error functions. GAB model and pseudo-first-order kinetic model exhibited the highest correlation coefficient. The nanoporous zeolite sample obtained through the surface response methodology is well-suited for industrial applications.

Mixture Adsorption in Nanoporous Zeolite and at Its External Surface: In-Pore and Surface Selectivity.

Using toluene, ethylene, and water as gas compounds with different representative molecular interactions, we perform atom-scale simulations for their mixtures to investigate the selectivity of the core nanoporosity and external surface in a prototypical zeolite. As expected, the overall behavior suggests that increasing the pressure of a given component promotes the desorption of the coadsorbing species. However, for water-toluene mixtures, we identify that the pseudohydrogen bonding between water and toluene leads to beneficial coadsorption as toluene adsorption in the low-pressure range promotes water adsorption. Moreover, when the zeolite is completely filled with water, toluene adsorption does not occur due to steric repulsion, and ethylene shows oversolubility as the amount of ethylene per water molecule is significantly larger than in bulk water. The underlying oversolubility mechanism is found to be due to localized ethylene adsorption in the density minima arising from the layering of water in nanoconfinement. Despite these specific effects, the relatively weak coadsorption effects in the zeolite nanoporosity, which are found to be reasonably captured using the ideal adsorbed solution theory, arise from the fact that adsorption of these gases having different molecular sizes occurs in distinct pore regions (channel type, channel intersection). Finally, in contrast to confinement in the nanoporosity, mixture adsorption at the external surface does not show coadsorption effects as it mostly follows the Henry regime. These results show that selectivity is mostly governed by the confinement effects as the external surface leads to a selectivity loss.

Optimal synthesis of dolochar derived faujasite zeolite X for highly effective Cd(II) removal

Cadmium-induced water pollution is a major environmental issue because of its persistent nature and adverse ecological impacts. Adsorption is a highly favored method due to its versatility and high efficacy in cadmium removal. Hence, the present work aims to develop a low-cost, highly effective adsorbent-dolochar-derived nanoporous zeolite to easily and effectively purify Cd(II) polluted water. The work focuses on the Cd(II) batch adsorption study using the optimal hydrothermal synthesis of a crystalline faujasite Zeolite X (ZX) from dolochar. The synthesis parameters were optimized using Response Surface Methodology, specifically Box Behnken Design (RSM-BBD), to maximize the crystallinity percentage. Variables such as initial Cd(II) concentration, solution pH, dosage, time, and temperature were studied for the Cd(II) batch adsorption study. The optimum conditions for synthesizing ZX include NaOH/Dolochar, crystallization temperature, and crystallization time of 1.375, 100 °C, and 11 h, respectively. The resultant XRD structure exhibited an average crystal size and crystallinity of 0.79 μm and 87.231 %, respectively. The average pore size, micropore volume, micropore area, and total surface area were 3.316 nm, 0.311 cc. g−1, 567.226 m2 g−1, and 583.117 m2 g−1, respectively. The maximum removal was accomplished with optimum conditions of 0.25 g.L−1 dosage, 80 min, at 313.15 K, and 6.5 pH. Adsorption isotherm results agreed with those hypothesized by Freundlich isotherm, with a maximum adsorption capacity of 714.285 mg g−1, and the pseudo-second-order kinetic model describes the adsorption kinetics well. The relevance of the results highlights the importance of using this dolochar-derived nanoporous zeolite as an adsorbent to effectively treat Cd(II) containing wastewater.

Investigating the adhesion and rheological properties of metal organic framework incorporated polyester fiber/zeolite imidazolium salt framework‐67‐modified asphalt composite

AbstractUtilizing efficient and cost‐effective modifiers is essential for the development of high‐performance asphalt materials. In this study, a polydopamine (PDA) chelated cobalt ion (Co2+)‐assisted in situ growth strategy was employed to anchor nanoporous zeolite imidazolium salt framework‐67 (ZIF‐67) on polyester (PET) fiber substrates for the preparation of styrene‐butadiene‐styrene block copolymer‐modified asphalt (SBS‐MA). Experimental results indicated that optimal fiber incorporation of 1.5% led to the best interfacial interaction at the modified asphalt fracture section. ZIF‐67 nanoporous structure acted as an organic–inorganic hybridization interfacial layer to enhance the fiber–asphalt interfacial interaction. The adhesion work of the modified fiber with SBS‐MA increased by 42.12%. Furthermore, the adhesion work, peeling work, and compatibility ratio of modified asphalt with aggregates were also improved. Similarly, the complex modulus of the 1.5% ZIF‐67–PDA–PET/SBS‐MA at 46°C was increased by 131.30% in comparison with that of the pristine SBS‐MA. More importantly, the synergistic effect of the highly thermally stable PET fibers and ZIF‐67 nanocrystals improved the thermal decomposition of SBS‐MA. These results suggest that ZIF‐67–PDA–PET fiber holds great promise for application in designing novel materials for the construction industry.

Aluminium alloy corrosion inhibition by composite pigment based on nanoporous synthetic zeolite and zinc dihydrogen phosphate

Aluminium alloy corrosion inhibition by composite pigment based on nanoporous synthetic zeolite and zinc dihydrogen phosphate

A review on the design of nanostructure-based materials for photoelectrochemical hydrogen generation from wastewater: Bibliometric analysis, mechanisms, prospective, and challenges

Years of study have shown that creating a commercial photoelectrode to solve particular bottlenecks, such as low charge separation and injection efficiency, short carrier diffusion length and lifespan, and poor stability, requires the employment of a variety of components. Developing photovoltaic-electrolysis, photocatalytic, and photoelectrochemical approaches to accelerate hydrogen production from solar energy has been highly competitive. Photoelectrochemical water splitting utilizing nanoporous materials is one of the promising approaches to produce hydrogen more efficiently, cost-effectively, and on a long-term basis. Nanoporous materials have been highly used in photoelectrochemical water-splitting systems and are crucial in numerous applications. Those materials have a porous structure and excellent conductivity, enabling the deposition of transition metal atoms and electrochemically active chemicals on a large active surface area. However, there remains a dearth of review articles exploring the application of nanoporous materials in photoelectrochemical reactions. Therefore, this review provides bibliometric statistics and various perspectives on a range of nanoporous materials, including indium, nickel, gold, copper, lead, silver, aluminum, silicon, tin, iron, zinc, titanium, bismuth vanadate, cadmium sulfide, and zeolites. Additionally, this review offers a comprehensive assessment of worldwide studies on utilizing nanoporous materials in photoelectrochemical cells. We show how morphological modifications to materials may improve charge transfer and, as a consequence, overall power conversion efficiency.ke The superior catalytic performance of nanostructures with varying levels of complexity has been discovered in photoelectrochemical reactions. Finally, significant issues and future research directions in the domains are discussed.

Low-Temperature Dynamics of Water Confined in Unidirectional Hydrophilic Zeolite Nanopores.

The dynamical properties of water molecules confined in the unidirectional hydrophilic nanopores of AlPO4-54 are investigated with quasi-elastic neutron scattering as a function of temperature down to 118 K. AlPO4-54 has among the largest pores known for aluminophosphates and zeolites (about 1.3 nm), though they are small enough to prevent water crystallization due to the high degree of confinement. Water molecular diffusion into the pore is here measured down to 258 K. Diffusion is slower than in bulk water and has an activation energy of Ea = (20.8 ± 2.8) kJ/mol, in agreement with previous studies on similar confining media. Surprisingly, local hydrogen dynamics associated with water reorientation is measured down to temperatures (118 K), i.e., well below the expected glass transition temperature of bulk water. The reorientational time scale shows the well-known non-Arrhenius behavior down to the freezing of water mass diffusion, while it shows a feeble temperature dependence below. This fast local dynamics, of the order of fractions of nanoseconds, is believed to take place in the dense, highly disordered amorphous water occupying the pore center, indicating its possible plastic nature.

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

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

Nanoconfinement-Enhanced Electrochemiluminescence for in Situ Imaging of Single Biomolecules.

Direct imaging of electrochemical reactions at the single-molecule level is of potential interest in materials, diagnostic, and catalysis applications. Electrochemiluminescence (ECL) offers the opportunity to convert redox events into photons. However, it is challenging to capture single photons emitted from a single-molecule ECL reaction at a specific location, thus limiting high-quality imaging applications. We developed the nanoreactors based on Ru(bpy)32+-doped nanoporous zeolite nanoparticles (Ru@zeolite) for direct visualization of nanoconfinement-enhanced ECL reactions. Each nanoreactor not only acts as a matrix to host Ru(bpy)32+ molecules but also provides a nanoconfined environment for the collision reactions of Ru(bpy)32+ and co-reactant radicals to realize efficient in situ ECL reactions. The nanoscale confinement resulted in enhanced ECL. Using such nanoreactors as ECL probes, a dual-signal sensing protocol for visual tracking of a single biomolecule was performed. High-resolution imaging of single membrane proteins on heterogeneous cells was effectively addressed with near-zero backgrounds. This could provide a more sensitive tool for imaging individual biomolecules and significantly advance ECL imaging in biological applications.

Incorporation of ZnO Nanoislands in Nanoporous Zeolite 13X for the Adsorption of Molecular Contaminants in Outer Space

Recently, zeolites have been selected as a potential adsorbent for capturing space molecular contaminants owing to their strong adsorption ability and extreme stability in a harsh environment. Considering the adsorption process in a vacuum environment, enhancement of the adsorption performance of the zeolites is required. Unfortunately, up to now, the improved adsorption behavior for the space molecular contaminants of the modified zeolite adsorbent under ultralow pressure has rarely been reported. Herein, a 13X/ZnO adsorbent was prepared by incorporating ZnO nanoislands into the nanoporous zeolite 13X via atomic layer deposition (ALD). It is found that a representative 13X/ZnO-50 exhibits an increased adsorption capacity toward dimethyl phthalate and the outgassing species of J133 adhesive even under the ultralow pressure of 10–5 Pa. This could be attributed to the synergistic effects of physical interactions and chemical adsorption associated with the unique cage structure of the zeolite and the incorporated ALD-grown ZnO nanoislands. This work provides a useful strategy for developing the adsorbents used in space molecular contamination control during space missions.

ZeoNet: 3D convolutional neural networks for predicting adsorption in nanoporous zeolites

ZeoNet, based on 3D convolutional neural networks and a volumetric distance-grid representation, delivers an exceptional performance in predicting Henry's constants for adsorption of long-chain hydrocarbon molecules in all-silica zeolites.