Microporous and Mesoporous Materials最新文献

Ordered mesoporous carbon CMK-1 was prepared via carbonization at a relatively low temperature (the first step) followed by partial graphitization (the second step of carbonization at higher temperature) inside the ordered mesopores of cobalt-loaded mesoporous silica MCM-48 using polyacrylonitrile (PAN) as a carbon/nitrogen source. This first step of the carbonization is called “infusibilization”, and the resultant material is denoted as PAN_inf. In an advanced temperature-programmed desorption analysis of the PAN_inf/MCM-48 composite, the temperature of the observed HCN signal indicated that carbonization was reduced from 550 to 450 °C by a Co catalyst. The amount of typical N₂ formation associated with the selective removal of pyridinic N species, resulting in the graphitic surface formation, also increased at a relatively high temperature (approximately 1000 °C) with the aid of the Co catalyst. The CMK-1 prepared through cobalt-catalyzed carbonization exhibited a higher electric double-layer capacitance with an Et₄N⁺BF₄^–/propylene carbonate electrolyte, and higher electrical conductivity than CMK-1 prepared without a catalyst. This also implied the progress of graphitization within the carbonaceous wall. These results suggest that the edge planes of the graphitic domains in CMK-1 are predominantly exposed on the surfaces of the carbonaceous walls, resulting in an increase in the number of adsorptive sites for the electrolyte during capacitance measurements.

The exploration of a suitable adsorbent for removal of toxic elements is a challenging task and in this context we have employed UiO-66 (Ce) based Metal Organic Frameworks (MOFs) synthesized by a room temperature method for the remediation of arsenic from aqueous solutions. The synthesized UiO-66 (Ce) and UiO-66 (Ce)-NH₂ MOFs were well characterized by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), Thermogravimetry (TG), Brunauer–Emmett–Teller (B.E.T.), Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Octahedral morphology was observed for UiO-66 (Ce) whereas the morphology of UiO-66 (Ce)-NH₂ synthesized by this method was non-uniform. Bare MOF exhibited higher surface area and higher thermal stability in contrast to the amine functionalized MOF. We have studied the arsenic adsorption on both these MOFs in varying pH conditions. The adsorption isotherm studies revealed that bare MOF is much superior for adsorption of arsenic with adsorption capacity of ∼308 mg/g whereas the adsorption capacity of amine functionalized MOF was mere 70 mg/g. Adsorption kinetic studies demonstrated that MOFs follow Pseudo Second Order (PSO) model and elucidated that the adsorption process is predominantly chemisorption in nature. UiO-66 (Ce) could be successively used multiple times without much penalty in the adsorption capacity and the thermodynamics of adsorption suggested it to be spontaneous and favorable. Finally, an overview of the probable mechanism of adsorption is discussed by employing different experimental techniques like XRD, FT-IR and XPS.

Metal species supported on zeolites have proven efficient synergistic mechanisms against microorganisms, reducing the overall toxicity. Likewise, the deposition of metals by ultrasound is a method that has drawn attention due to its efficiency, low cost, and environmental friendliness. Hence, the antimicrobial properties of Zinc (Zn) species supported on LTA zeolite (NaA) via a sono-assisted method were explored in this study. Zeolite A modified with Zn species by ion exchange or sono-assisted precipitation of active Zn species (Zn(OH)₂, ZnO, and ZnO₂) was evaluated in a screening experiment by agar diffusion and micro broth assays. Finding that at a concentration of 30 mg/mL, drying the ZnO₂@NaA material activated a mechanism that inhibited the growth of E. faecalis by 100 % while eliminating the drying step, an inverse effect was produced, now inhibiting the growth of E. coli. This sample also presented promising properties as an antimycotic agent inhibiting the growth of C. albicans by 90 % at a concentration of 1 mg/mL. In addition, a viability analysis was performed on fibroblasts, demonstrating a potential toxicity reduction.

This ZnO₂@NaA material holds promise as an antibacterial and antifungal agent. Presenting a novel sono-assisted methodology for tuning the selectivity of inhibition mechanisms for peroxide-containing species in zeolites. This selected zinc-containing zeolitic material (ZnO₂@NaA) was then characterized by UV–Vis, FTIR, Raman spectroscopy SEM, XRD, and ζ-potential, evidencing the presence of ZnO₂ nanoparticles. This study opens perspectives for developing new antimicrobial Zn-containing zeolitic materials through a sono-assisted methodology for increasing selectivity in the inhibition mechanisms.

Electrocatalysis is essential for enhancing the energy conversion efficiency of zinc–air batteries. Nonetheless, the high cost and insufficient stability of electrocatalysts continue to hinder their commercial application. This study introduces a bifunctional composite electrocatalyst, NiCo–NG, consisting of Ni/Co bimetallic nanoparticles. The in situ integration of nanoscale graphene mitigates the agglomeration of Ni/Co metal atoms, resulting in a porous structure with a high specific surface area up to 244.6 m² g⁻¹. Notably, the NiCo–NG catalyst demonstrates enhanced conductivity, achieving an oxygen reduction reaction (ORR) half-wave potential of 0.793 V and a limiting current density of 7.64 mA cm⁻². This catalyst exhibits superior performance to commercial Pt/C electrodes, which exhibit a half-wave potential of 0.836 V and a limiting current density of 0.6 mA cm⁻². Moreover, the overpotential for the oxygen evolution reaction (OER) at a current density of 10 mA cm⁻² is only 306.3 mV. The introduction of Ni significantly augments the catalytic activity. Employing this dual-functional catalyst in rechargeable zinc–air batteries yields a maximum power density of 181.9 mW cm⁻² and a specific capacity of 804.2 mAh·g_Zn⁻¹. In addition, the fabricated battery demonstrates remarkable stability, enduring up to 3000 charge–discharge cycles. Ultimately, this research offers a novel electrocatalyst that could advance the commercialization of zinc–air batteries.

In this study, zeolite synthesized based on bentonite via the alkali fusion-hydrothermal method, and the effects of different synthesis parameters on the crystallinity and silicon-aluminum ratio of zeolite were investigated. The zeolite particles were modified by cationic surfactant and magnetized to prepare a MCTAB-BZ composite, which was then applied to the adsorption of diethyl phthalate (DEP) from aqueous solution. The effects of operating factors, including pH value, adsorption dosage, temperature, and adsorption time on the kinetic and isotherm adsorption behavior were studied. Highly crystalline ANA-zeolite can be prepared with the alkali content of 1:1, the aging time of 20 h, the aging water content of 1:15, and the crystallization time of 24 h. The results of the adsorption experiment show that the novel adsorbent-MCTAB-BZ composite shows the best adsorption capacity when the adsorption dosage is 6.25 g/L, temperature is 30 °C and adsorption time is 180 min at the original pH value of the aqueous solution. The adsorption results are presented well by the pseudo-second-order kinetic model and the Freundlich isotherm model.

In the face of an extensive literature on the use of zeolites for the removal of metals from water for environmental purposes, it is seldom considered that some metals are also essential nutrients for life and that zeolites could be profitably used to dose their release. Among these, Zn is a key micronutrient, and when its demand by crop is not fully balanced by adequate accessibility, fertilization must be provided using Zn salts that can be, however, easily leached and partly wasted in the environment.

In an attempt to solve this critical problem, a new controlled-release formulation of Zn using zeolite-containing geomaterials was designed, prepared, characterized, and tested by applying a sequential, multi-method approach. Different formulations were trialed, and the most effective included 30 wt% pumice by-product and 70 wt% clinoptilolite-rich zeolitized tuff, with about 20 mg/g of exchangeable Zn²⁺. The enrichment process reached equilibrium after about 8 h, a timing well-tuned with technology transfer. Desorption kinetic tests in a weekly acid environment revealed gradual Zn release, with about 4.28 wt% released after 6 h. When tested as a foliar fertilizer on Vitis vinifera, this formulation demonstrated superior resistance to leaching under simulated rainfall conditions compared to conventional ZnSO₄·6H₂O fertilizer, maintaining the initial level of Zn (130 mg/kg of dry leaves), while about 22 % of the Zn applied with ZnSO₄·6H₂O was loss. This outcome was plausibly due to mineral particle adhesion to leaf. Preliminary cost estimates suggest that the product designed here can be placed in the market with competitive sales prices.

In this study, an exploration of molecular interactions between CH₄, CO, CO₂, H₂O, N₂, NH₃, NO, NO₂, O₂, SO₂ gas molecules and B₁₂N₁₂(Zn) nanocage is conducted using advanced computational techniques, ωB97XD/Def2tzvp, unraveling fundamental behaviors. Employing global optimization methods and sophisticated tools like the bee colony algorithm in ABCluster software, the research offers insights into energy adsorption processes, confirming molecular stability through DFT calculations. The determination of electrophilicity index values through conceptual DFT analysis sheds light on relative reactivity levels and charge transfer phenomena, emphasizing that in some cases the nanocage's role as a potential electron acceptor. Natural bond analysis of charge transfer direction and valence shell orbital interactions enriches understanding, supported by comprehensive parameter compilation and critical point visualization. Further confirmation of interaction types and strengths through G(r)/V(r) ratios and ELF values enhances comprehension through quantum theory of atoms in molecule analysis. Ultimately, this study contributes significantly to computational chemistry, laying foundations for molecular design and engineering advancements. It sets the stage for future progress in materials science and catalysis, promising innovation in sustainable energy solutions and technological development.

Different crystal formation patterns of Fe_xO_y species over two zeolitic supports were observed. Starch was used in the synthesis of ZSM-5 to generate a zeolite with supplemented mesoporosity in addition to the traditional microporous structure. Fe was incorporated into the zeolitic matrices through hydrothermal synthesis of hematite nanoparticles. Two zeolitic catalysts with different activities in a photo-Fenton reaction were obtained. The materials were thoroughly characterised by XRD, UV–Vis DRS, TPR, FIT-IR, NMR, SEM, EDS, TEM, Mössbauer Spectroscopy and N₂ adsorption-desorption isotherms. Methyl orange, a persistent anionic dye in water, was chosen for photocatalytic degradation testing. Promising results were obtained when hematite nanoparticles were supported onto hierarchical ZSM-5. The presence of extra-framework aluminium served as a nucleation site, leading to the formation of numerous smaller hematite crystals, enhancing the photocatalytic performance of the catalyst.

The surface chemistry and the textural properties of nitrogen-doped zeolite-templated carbon materials (N-ZTC) are decisive for their functionality in CO₂ capture. This study analyses how the synthesis conditions affect the structure, formation of N-containing functional groups, thermal stability and CO₂ capture of N-ZTC in comparison with nitrogen-free ZTC. Faujasite as a hard template and chemical vapour depositions (CVD) with propene and acetonitrile were used for the synthesis of ZTC and N-ZTC, respectively. XRD, SEM, N₂ and CO₂ sorption, XPS and TG/DSC analyses showed that the structural ordering and microporous volume in N-ZTC increases with increasing synthesis temperature. Conversely, at higher temperatures, the content of basic pyridinic groups in N-ZTC decreases in favour of stable graphitic nitrogen. The Lewis acid−base interaction of CO₂ with the pyridinic groups provides the highest adsorption heats, the highest affinity for CO₂ compared to N₂ and enhances CO₂/N₂ selectivity (CO₂/N₂ selectivities of 127, 95, 89, and 66 for N-ZTC_750°C, N-ZTC_800°C, N-ZTC_850°C and ZTC, respectively). The maximum adsorption capacity was achieved for N-ZTC_800°C still yielding a high content of basic groups and a larger micropore volume compared to N-ZTC_750°C. The decisive factor for the selectivity is thus the presence of basic centers attainable in N-ZTC at a lower synthesis temperature. The maximum adsorption capacity is associated with a large microporous volume and basic centers in N-ZTC synthesized at medium temperatures. The energy of CO₂ adsorption by Lewis acid−base interactions and well-developed micropores are decisive for high selectivity and large adsorption capacity for efficient CO₂ capture using N-ZTC materials.

Improving the zeolite adsorption separation efficiency of individual xylene isomer with high purity from their mixture is still a pressing challenge in the fine chemical industry. Herein, plate-like silicalite-1 (p-S-1) zeolite crystals with short b-axis thickness have been successfully synthesized by combination of tributylphosphine oxide (TBPO) modifier and F⁻-assisted crystallization method to first investigate the separation property of xylene isomers. The morphology and structure of the p-S-1 zeolite crystals were characterized by XRD, FTIR, BET, SEM and TEM. The results showed that the p-S-1 zeolite crystals with thickness of about 50 nm along the b-axis and high crystallinity, as well as extremely rich micropores, were obtained by crystallizing the gels with TBPO/SiO₂≥0.04. By static adsorption experiment and fixed bed experiment, xylene isomers selective adsorption separation property of the p-S-1 zeolite crystals prepared at TBPO/SiO₂ = 0.04 was investigated. The static adsorption experiment demonstrated that the p-S-1 zeolite crystals exhibited higher adsorption capacity of p-xylene (p-X) and more excellent xylene isomers separation performance than that of the bulk coffin-shaped silicalite-1 (c-S-1) zeolite crystals because of the shorter mass transfer channel and larger diffusivity differences between p-X and o-X/m-X/EB. The dynamic adsorption experiment in simulated five-component solutions diluted by isooctane (IO) indicated that the p-S-1 zeolite crystals had excellent xylene isomers selective adsorption separation performance. The optimum dynamic xylene isomers selective adsorption separation factors for p-X/o-X, p-X/m-X and p-X/EB were 25.41, 36.45 and 11.57 at 150 °C, respectively. The regeneration experiment also indicated that the p-S-1 zeolite crystals had more stable structure and longer lifetime. This work suggested that the p-S-1 zeolite crystals had great potential as new adsorbent for selective adsorption separation of xylene isomers.