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A Spectroscopic Study of Tautomeric Equilibrium of Salicylideneaniline in ZSM-5 Zeolites
摘要： Salicylideneaniline (SA) sorbed in cation-exchanged M-ZSM-5 (M = H+, Li+, Na+, K+, Rb+, Cs+ and Zn2+) zeolites was studied by spectroscopic techniques assisted by quantum-chemical calculations. The nature of extra-framework cations present in the zeolite void was found to affect the spectral signature of the sorbed SA molecule that points to the shift of tautomeric equilibrium between the enol and keto forms. Small size cations, such as H+ and Li+, stabilize a cis-keto SA tautomer along with a enol one in the zeolite structure. The calculations indicate that the sorbed cis-keto tautomer may have the dipole large enough to be considered as a zwitterion. New features appearing in the spectra with the increase of the cation size were attributed to the presence of trans-keto SA tautomer, which up to now has been observed only in time-resolved spectroscopic experiments. A strong interaction of the molecule with cations in Zn-ZSM-5 zeolite results in the chelation of enol SA with the divalent Zn2+ ions. The results of the study suggest that the tautomeric equilibrium of molecules belonging to the Schiff base family can be tuned by the con?nement in the nanoporous materials via a choice of topology of zeolite framework and the nature of extra-framework cations.
关键词： spectroscopy,tautomer,DFT calculations,ZSM-5,equilibrium,salicylideneaniline,zeolite
更新于2025-11-19 16:56:35
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ZIF-8 derived hollow CuO/ZnO material for study of enhanced photocatalytic performance
摘要： Tetracycline hydrochloride (TC) is a broad-spectrum antibiotic extensively used in medical and veterinary fields. However, its excess harms the environment and human health. Recently, construction of CuO/ZnO heterojunctions has a very good effect in the treatment of organic matter in water. In this study, we used zeolite imidazolate framework (ZIF-8) as initial material to synthesize porous and hollow CuO/ZnO photocatalysts for catalytic degradation of TC. The results show that the synthesized CuO/ZnO has the characteristics of porous hollow polyhedron when the molar ratio of Cu and Zn is 0.1. Obviously, photocatalytic degradation rate was better comparing to CuO/ZnO nanoparticles as well as pure ZnO and CuO particles, respectively, which could reach 87% at 60min under visible light (λ>420 nm) and has good stability. Porous hollow CuO/ZnO composites are very promising for effective and environmentally friendly degradation of tetracycline hydrochloride in water.
关键词： Photocatalysis,Tetracycline hydrochloride,Zeolite imidazolate frameworks (ZIF-8),Hollow CuO/ZnO
更新于2025-11-14 17:04:02
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Ammonia-Responsive Luminescence of Ln3+-β-diketonate Complex Encapsulated within Zeolite Y
摘要： Assembling Ln3+(HPBAn) (Ln = Eu or Tb, HPBA = N-(2-pyridinyl)benzoylacetamide) in the cavities of zeolite Y (ZY) via the “ship-in-a-bottle” strategy leads to the formation of novel luminescent composite, Ln(HPBAn)@ZY, whose luminescence can be easily modulated by ammonia on the basis of the energy level variation of HPBA after deprotonation process. Additionally the bimetallic complex doping sample, Eu0.5Tb0.5(HPBAn)@ZY, show great potential as self-referencing luminescent sensor for detecting low ammonia concentration of 10?12–0.25 wt%.
关键词： zeolite Y,luminescence,Ln3+-β-diketonate complex,ammonia-responsive
更新于2025-11-14 15:18:02
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Study on the enhancement of photocatalytic environment purification through ubiquitous-red-clay loading
摘要： Tungsten oxide (WO3) is regarded as a promising visible-light-sensitive photocatalyst, but its activity is not high. Further enhancement of its activity has been anticipated using techniques such as loading of a cocatalyst to apply the oxide to indoor environmental remediation; Pt has been reported as a good cocatalyst for WO3 photocatalysis. However, Pt is precious and expensive metal. Thus, in this study, we sought to find a ubiquitous cocatalyst and suitable photocatalyst system. As a result, this study revealed that loading a ubiquitous material of red-clay enhanced WO3 photocatalytic activity remarkably. As photocatalyst samples, mixtures consisting of the clay and WO3 with different weight ratios were prepared using a simple kneading method. Their photocatalytic activity was evaluated from decomposition of harmful organic contaminant, 2-propanol into CO2 under visible-light irradiation. The WO3 with 10% of the clay loading showed the highest activity among the samples and much higher activity than pure WO3. This higher activity might derive from the clay’s promotion of H2O2 decomposition and charge separation (holes and electrons). The H2O2 was generated from photocatalytic O2 reduction. This formation and accumulation on the pure WO3 surface led to decreased activity.
关键词： TiO2,Zeolite,Natural mineral,Optical absorption,Remediation
更新于2025-09-23 15:23:52
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Identification and structures of the X-ray induced luminescence centers in the zeolites Zr,X,Cs,Na-LTA, X = Cl, Br, and I
摘要： Zr4+ and halide anions were introduced into zeolite A (LTA) by treating Cs,Na-A with ZrX4(g), X = Br and I, under anhydrous conditions. The crystal structures of Zr,Br,Cs,Na-A and Zr,I,Cs,Na-A were determined by single-crystal crystallography with compositional confirmation by scanning electron microscopy energy-dispersive X-ray (SEM-EDX) analysis. Their X-ray induced luminescence (XIL) properties were thoroughly studied. These structures and XIL properties were compared with those of previously reported Zr,Cl,Cs,Na-A. In both structures, most Na+ and Cs+ ions occupy positions similar to those found in Cs,Na-A and Zr,Cl,Cs,Na-A. About 9% of the large cavities of Zr,Br,Cs,Na-A are centered by ZrBr6 2- ions. In Zr,I,Cs,Na-A, about 6% are centered by ZrI6 2-. These octahedral ZrX6 2- ions are each held in place and stabilized in their large cavities by 24 bonds between all six of its halide ions and eight surrounding Cs+ ions. They are further bridged by 8-ring Cs+ ions to form a cubic 3-dimensional Cs11ZrX6 9+ continuum in the surface volume of the crystal. Their XIL domain peaks have red-shifted from 495 nm for Zr,Cl,Cs,Na-A, to 520 nm for Zr,Br,Cs,Na-A, and to 640 nm for Zr,I,Cs,Na-A. This may be because the self-trapped excitons (STE) of ZrBr6 2- and ZrI6 2- have smaller band gaps than that of ZrCl6 2-, a result of the valence band maximum 4p energy level in Br- being higher (5p in I- even higher) than the 3p energy level in Cl-.
关键词： ZrBr6 2- and ZrI6 2-,Crystal structure,Extraframework Zr4+,Luminescence,Zeolite A
更新于2025-09-23 15:23:52
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Poly(azomethine-urethane) and zeolite-based composite: Fluorescent biosensor for DNA detection
摘要： In the present paper, a highly selective and sensitive fluorescent biosensor based on poly(azomethine-urethane) and zeolite for the determination of DNA molecules was developed. Zeolite was chosen to enhance with anionic or cationic functional groups in polymer matrix and interaction between polymer and DNA. Several parameters such as polymer concentration, pH and incubation time effect on the sensitivity of the fluorescent biosensor were optimized. Linear range was determined between 2.50 and 25.00 nmol/L DNA concentration and limit of detection (LOD) of the biosensor was calculated as 0.095 nmol/L under the optimal conditions. Interference study were also performed in the presence of different amino acids, cations and organic compounds. The results clearly indicated that the tested cations and compounds were not induced a significant fluorescence change and the proposed zeolite-based biosensor was shown a good selectivity for DNA.
关键词： fluorescent sensor,DNA,Zeolite,biosensor
更新于2025-09-23 15:23:52
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Adsorption and photodegradation efficiency of TiO2/Fe2O3/PAC and TiO2/Fe2O3/zeolite nanophotocatalysts for the removal of cyanide
摘要： The synthesized TiO2/Fe2O3 nanostructures supported on powder activated carbon (PAC) and zeolite at different mole ratios of Fe3+/TiO2 were characterized by XRD, XRF, FESEM, EDX, TEM, FTIR, BET and, PL analyses and their cyanide photodegradation mechanism was thoroughly discussed. The results confirmed not only TiO2/Fe2O3/PAC had higher photocatalytic and adsorption capability but also better structural stability and reusability for cyanide removal than TiO2/Fe2O3/zeolite. The first order kinetics model indicated that the photodegradation rate using TiO2/Fe2O3/PAC was 1.3 times higher than that of TiO2/Fe2O3/zeolite. The response surface methodology (RSM) assessment showed that pH, irradiation time and initial cyanide concentration using UV/H2O2/TiO2/Fe2O3/zeolite system had more effects on the degradation respectively; whereas the effectiveness of UV/H2O2/TiO2/Fe2O3/PAC process was highly influenced by initial cyanide concentration than the other two parameters. High R2 and well-fitted residual plots approved the accuracy of the models in predicting the cyanide degradation efficiency using both the photocatalysts.
关键词： and adsorption comparison,Cyanide,Response surface methodology (RSM),TiO2/Fe2O3/zeolite and TiO2/Fe2O3/PAC photocatalysts,Photodegradation,Kinetic
更新于2025-09-23 15:23:52
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Facile fabrication of well-polarized Bi <sub/>2</sub> WO <sub/>6</sub> nanosheets with enhanced visible-light photocatalytic activity
摘要： Designing a templating strategy for directing mesopore growth along different crystallographic directions is essential for fabricating two- or three-dimensional single-crystalline mesoporous zeolites. However, so far, mesopores formed in MFI zeolites by soft templates have mostly been generated by disrupting growth along the b axis; generating mesopores by disrupting growth along the a axis is rare. Herein, a single-crystalline mesoporous MFI zeolite (SCMMZ) with sheet-like mesopores layered along the a and b axes was synthesized using a triply branched surfactant with diquaternary ammonium groups connected to 1,3,5-triphenylbenzene by a six- and eight-carbon alkyl chain (TPB-6 and 8). The sheet-like mesopores were embedded in the MFI framework and were retained even after calcination. Molecular mechanics calculations provided evidence of low binding energy configurations of the surfactant that directed the growth of straight and zigzag channels along the b and a axes, respectively. The formation of nanosheets was attributed to the geometric matching of the arrangement of the aromatic groups to the zeolite framework.
关键词： mesoporous zeolite,transmission electron microscopy,surfactants,self-assembly,MFI
更新于2025-09-19 17:15:36
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Laser irradiation for controlling size of TiO2-Zeolite nanocomposite in removal of 2,4-dichlorophenoxyacetic acid herbicide
摘要： This study has focused on the synthesis of TiO2-Zeolite nanocomposite through a sol-gel approach. The decrease in the size of the nanocomposite considers as a primary parameter to improve the photocatalytic activity. In this regards fabricated samples exposed to laser irradiation (532 nm) at four different time intervals in order to investigate the size variation of nanocomposite. FTIR, UV-Vis, XRD, DLS, SEM and EDX analysis were applied to characterize and determine the size of the products. Optimized nanocomposite sample, in term of the particle size, used for photodegradation of 2, 4-D herbicide from aqueous solution. Photodegradation carried out under UV- irradiation (12 W) and Xe lamp irradiation (200 W). Obtained results showed that laser irradiation time has a substantial effect on controlling the size of nanocomposite. Results from the photocatalyst study indicated that the elimination of 2, 4-D under the Xe lamp irradiation was higher compared to the UV-irradiation. Also, the ?nal synthesized nanocomposite exhibited higher catalytic activity for photodegradation of 2,4-D compared to pure Zeolite and pure anatase TiO2 samples. The reusability of TiO2-Zeolite nanocomposite was studied in four successive cycles to evaluate the removal of 2,4-D under UV- irradiation.
关键词： photocatalyst,laser irradiation,zeolite,nanocomposite,TiO2,2, 4-D
更新于2025-09-19 17:13:59
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Pulsed laser ablated zeolite nanoparticles: A novel nano‐catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthene and <i>N</i> ‐aryl‐1,8‐dioxodecahydroacridine with molecular docking validation
摘要： There is an increasing interest in the synthesis of metal nanoparticles (NPs) from bulk metals using pulsed laser ablation in liquids (PLAL), as it offers an easy and simple synthesis route. In this work, zeolite NPs (molecular sieve 4A) were successfully synthesized by the PLAL technique, and characterized by X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, and high‐resolution transmission electron microscopy. Data obtained confirm the formation of the crystalline phase of zeolite. The synthesized catalyst (zeolite molecular sieve 4A) was used as an efficient and facile promotor for the synthesis of xanthene and acridine derivatives. Molecular docking of the synthesized compounds was validated using quinone reductase 2 (NQO2) and acridine orange as the ligand, with the synthesized molecules showing good drug–ligand interaction on the active site of NQO2, compared with that of acridine orange.
关键词： zeolite,acridine,xanthene,laser ablation,nanoparticles,dimedone
更新于2025-09-12 10:27:22