A chabazite-type zeolite was prepared by the hydrothermal method. Before ion exchange, the chabazite was activated with ammonium chloride (NH
Cl). The ion exchange process was carried out at a ...controlled temperature and constant stirring to obtain ion-exchanged chabazites of Ti
chabazite (TiCHA), Zn
chabazite (ZnCHA), Cu
chabazite (CuCHA), Ag
chabazite (AgCHA) and Au
chabazite (AuCHA). Modified chabazite samples were characterized by X-ray diffraction (XRD), scanning electron microscope equipped with energy-dispersive spectroscopy (SEM-EDS), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), N
adsorption methods and UV-visible diffuse reflectance spectroscopy (DRS). XRD results revealed that the chabazite structure did not undergo any modification during the exchange treatments. The photocatalytic activity of chabazite samples was evaluated by the degradation of methylene blue (MB) in the presence of H
O
under ultraviolet (UV) light illumination. The photodegradation results showed a higher degradation efficiency of modified chabazites, compared to the synthesized chabazite. CuCHA showed an efficiency of 98.92% in MB degradation, with a constant of k = 0.0266 min
following a first-order kinetic mechanism. Then, it was demonstrated that the modified chabazites could be used for the photodegradation of dyes.
In this work, we report an optofluidic system for manipulation of orientation of zeolite crystals near the bottom of a rectangular cross-sectional, straight, quartz microfluidic channel. Manipulation ...is accomplished by using two computer-controlled syringe pumps that generate adequate hydrodynamic forces for translation and rotation of crystals. Rotation of a crystal around its longitudinal axis allows us to inspect its four major faces for defects. Coffin-shaped zeolite crystals have been studied by several authors by fixing them to a substrate, using two different crystals to assess the roof and gable orientations. The proposed system permits complete assessment of a single crystal by shifting it between roof and gable orientations; moreover the medium can be controlled. Computational fluid dynamics simulations show that crystals in free motion near the bottom of the channel should move faster than the velocity estimated from video. An opposing force, which prevents the crystals from moving freely, has been calculated in order to match translation velocities from simulations and experiments for three given flow rates. The reported optofluidic system is proposed as a novel tool that we believe will open new possibilities for individual zeolite crystal assessment by manipulation of its orientation and medium control.
•Tuning of Fe active sites in a modified faujasite can be achieved by an ultrasonic treatment.•Fe modified Y zeolite possesses active sites that can hydrolyze lactose at 60 °C and even 30 °C.•A ...sonoassisted prepared Fe modified Y zeolite can transform lactose into value added compounds.
Research has focused on biomass as a sustainable energy source, driving biomass valorization to convert carbohydrates. The price of lactose has dropped below the production cost, urging exploration for diverse applications, such as conversion into value-added compounds. Zeolites, especially Y zeolite, enhance hexose conversion when modified with metals. Fe-modified zeolites show promise, with controlled Si/Al ratios impacting acidity and selectivity. The recent challenges remain in active site comprehension, catalyst tunability, and reaction optimization. Therefore, this study explores the selective hydrolysis of lactose, limiting undesired side-product formation catalyzed through a sono-assisted modified zeolite Y with Fe. The obtained series of Fe-modified zeolite Y were evaluated for the hydrolysis of lactose in a screening experiment. The samples with the higher potential were further used to optimize reaction conditions by a response surface methodology (RSM). This revealed that the samples prepared at high pH generated more impurities and that higher temperatures and lactose concentrations favored hydrolysis. Despite their apparent similarities, the selected Fe-modified zeolite Y samples (Fe5Y and FeYII) highlight distinct catalytic behaviors and active sites. Employing UV-Vis spectroscopy, FTIR spectroscopy, and magnetic thermal gravimetric analysis (MTGA), various Fe active sites were detected, including α-Fe(II), FeOx nanoparticles, and iron oxides. These active sites give insight into the mechanisms involved with temperature and time, which play critical roles—evidencing the potential of sono-assisted iron modification of zeolite Y to achieve selective lactose hydrolysis. These findings contribute to understanding metal-zeolite composites as bifunctional catalysts and their application in sustainable processes. Furthermore, this research highlights the complexity of catalytic reactions of modified zeolites and their potential for fine-tuning active sites for various applications, particularly lactose hydrolysis. Such advancements hold the promise of propelling the field of sustainable energy and catalysis towards a more efficient and environmentally friendly future.
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