Topics in Catalysis最新文献

Innovations in fuel cells bring important developments in obtaining energy. Especially with the anodic reactions of fuel cells and the catalysts used in the anodic part, it provides an increase in energy efficiency. With this study, modification of durable and high catalytic activity targeted carbon nanofibers (CNFs) with Platinum nanostructures (CNF@Pt) developed for alcohol oxidation was provided. Further, CNF@Pt was characterized by Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD). According to Debye Scherrer, the crystalline particle size was approximately 2.27 nm, and the CNF diameter was measured as 161.57 nm according to the TEM results. Besides, the anodic reactions of methanol, ethanol, and 2-Propanol for direct alcohol fuel cells (DAFC) were investigated. Cyclic Voltammetry (CV), Chronoamperimetry (CA), and recycling performance tests were demonstrated in ideal operating rates of the catalyst. One of the highest anodic peak currents were measured as 145.43, 101.56, and 34.54 mA.cm^− 2 for methanol, ethanol, and 2-propanol at a scanning speed of 50 mV/s, respectively. The CNF@Pt catalyst was also very stable and durable in stability tests. In this study, it has been seen that carbon-based fiber materials are an ideal catalyst to increase efficiency in fuel cells and to make sense of the results obtained in their use in different alcohol types.

Abstract

Dyes as one of the majority critical environmental pollutants from industrial wastewaters, have caused many concerns for researchers. In this research an effective photocatalyst based on La₂O3-SiO₂ nanocomposite was prepared and evaluated for degradation of toluidine blue (TB) dye. The prepared photocatalyst was illustrated impressive performance in degradation of TB equal to 97% by visible light irritation. Accuracy of synthesized nanocomposite was studied by some technics including FE-SEM, FT-IR, EDX and mapping analysis. Also the effective parameters in degradation percent of TB such as pH, temperature, time, concentration and the amount of nanocomposite were investigated and optimized equal to amounts of 8.0, 25℃, 80 min, 3.0 µg/mL and 0.04 mg respectively.

For industrial processes—like waste incineration—it is necessary to reduce solid components (like dust or fly ash) as well as gaseous components (like dioxins, CO and other harmful hydrocarbons) to fulfill legal requirements. Therefore, catalytically functionalized filters based on polymers already exist. However, it is known that such filters are always constructed in multiple layers to prevent the migration of catalyst particles. This study demonstrates that it is possible to prepare a stable catalytic functionalized single-layer filter based on polyester needle felt by using flame spray pyrolysis. The catalyst is a low temperature active Pt/TiO₂ with a loading weight of 38 g/l on the filter. Via SEM images the uniform distribution of the catalytic particles even in the deeper regions of the single-layer filter was proven. The structure was confirmed after experiments under realistic conditions—migration could not be obtained. Likewise, it was obtained that the oxidative conversion of carbon monoxide (CO) to carbon dioxide (CO₂) is completely even at temperatures below 100 °C. Furthermore, comparative studies with catalysts on a honeycomb and a ceramic foam have shown that the conversion on the polyester needle felt textile catalyst is comparable.

Oxidovanadium(V) complex [V^VO{Hen(3,5-dcp)₄}] (where H₄en(3,5-dcp)₄, is a Mannich base synthesized from ethylenediamine, paraformaldehyde and 2,4-dichlorophenol) has been anchored onto chloromethylated polystyrene (PS–Cl) cross-linked with divinylbenzene to obtain [V^VO{en(3,5-dcp)₄}]@PS (@ refers to anchoring of complex onto polymer), a heterogeneous compound. Both of the synthesized (homogeneous as well as heterogeneous) vanadium compounds, after characterization, have been explored as biomimicking model catalysts for the type II copper site in phenoxazinone synthase. These compounds catalyze the oxidative condensation of o-aminophenol (OAP) into 2-aminophenoxazine-3-one (APX) by utilizing aqueous hydrogen peroxide in acetonitrile. Various reaction conditions like amounts of catalyst and oxidant, and temperature have been optimized to obtain maximum yield of APX. The polymer-immobilized complex demonstrates excellent catalytic activity, giving 96% yield of 2-aminophenoxazine-3-one under the optimized reaction conditions selectively. Its homogeneous analogue i.e. [V^VO{Hen(3,5-dcp)₄}], is also active and exhibits 83% yield. The heterogeneous catalyst i.e. [V^VO{en(3,5-dcp)₄}]@PS is stable, recyclable and reusable.

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In this study, mixed phase (tetragonal and monoclinic) Zirconia nanoparticles (ZrO₂ NPs) namely, ZS3, ZS7 and ZS10 were synthesized via hydrothermal method at different pH values of (3, 7, 10) respectively. A combination of Powder X-ray diffraction (PXRD), High Resolution Transmission Electron Microscopy (HRTEM), and Selected Area Electron Diffraction (SAED) characterization techniques confirmed the formation of mixed phase ZrO₂ nanoparticles. The photocatalytic behavior of synthesized ZrO₂ NPs was examined for the degradation of anionic Congo Red (CR) Dye under visible light irradiation. A systematic study of the efficiency of the prepared ZS3, ZS7 and ZS10 nanoparticles was compared and it was found that ZS7 outperformed the ZS3 and ZS10 materials, having removal efficiency of up to 98.9% with 0.1 g of the prepared ZS7 nanoparticles for 75 ppm of Congo Red (CR) dye. Furthermore, the surface area analysis revealed that among the prepared materials, ZS7 exhibited the highest surface area, thereby corroborating the finding of its superior catalytic efficiency. Under the optimized experimental conditions, the degradation of dye followed first-order kinetics. ZS7 showed the highest removal efficiency in just 60 min of contact time for all the CR dye concentrations ranging from 50 to 100 ppm, making it a superior catalyst for the efficient removal of the targeted Congo Red dye.

Abstract

The presence of contaminants, such as synthetic dyes and herbicides, in water has led to serious environmental and human health problems worldwide. Therefore, the effective removal of pollutants from aquatic environments has attracted considerable attention. The combination of metal-organic frameworks and advanced carbon materials has attracted great attention in many application fields because the hybrid material has many positive properties from both components. In this paper, NCDs/FeNH₂BDC composite was fabricated through in situ synthesis, in which N-containing carbon dots (NCDs) were mixed with MOF precursor solution in different ratios before undergoing the cooling step. It has been demonstrated that introducing a certain amount of N-containing carbon dots affects the characteristic features and improves the photocatalytic performance of the final product. The optimal doping content of N-containing carbon dots in the NCD/FeNH₂BDC composite was determined to be 400 mg. SEM images show that S400 appears as hexagonal micro-axial crystals with an average size of 500 nm. In addition, the S400 catalyst also exhibits excellent photocatalytic activity for the degradation of Rhodamine B at a pH range of 3 to 5. Under optimal conditions, Rhodamine B is achieved within 60 min and the yield Removal reached nearly 100% after 5 cycles. Finally, the efficiency of S400 in treating the active ingredient pretilachlor in pesticides in water is up to 93.08%.

Arsenic, a metalloid that exists by nature, reaches the earth either by natural or anthropogenic events and is considered an emerging pollutant. The existence of arsenic in soil systems is a fate to the environment since it is mobile and being transported to other systems because of its bioavailability and speciation process. Arsenic transformation in the soil and its thorough understanding of how it enters plant systems are crucial. Notably, transporters are responsible for most of the arsenic that enters the plant system. Consumption of crops or animals and drinking water polluted with arsenic are the prime factors in transmitting arsenic to people. Severe adverse effects on humans arise as an outcome of long-term contact with arsenic-rich foodstuff and water. An effort has been made to outline the several sources and their dynamics in the surroundings and health impact on humans in this review. In addition, various strategies have been practiced to remove arsenic in the soil and water systems is also addressed.

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The rapid advancement of nanotechnology in the production of nanomedicine agents holds enormous promise for improving cancer therapy techniques. Nanomedicine products offer the possibility of developing complex targeting approaches as well as multifunctionality. Nanotechnology has been examined for the detection of extracellular cancer biomarkers and cancer cells, as well as in vivo imaging, sensitive and selective, accuracy, and multiplexed detection capacity. In fact, nanoparticles have the potential to not only address the limitations of traditional cancer diagnosis and treatment, but also to open up entirely new possibilities and develop cutting-edge technology for tumour detection and treatment. Nano carriers are used to increase target tumour cell specificity and delivery capability to the tumour site, enhancing therapy efficacy while reducing unwanted side effects. Nanocarriers that respond to exogenous or endogenous stimuli have emerged as a promising alternative to target drug delivery. In this review intervention of nanoparticle system for cancer types like Lung cancer, Breast cancer, Melanoma, Colorectal cancer, Bladder cancer are discussed. Further focused on the advancement of nanocarriers for cancer diagnosis and treatment. The critical review takes deeper insight on nanocarrier-based cancer therapy.

This study proposed biodiesel production from refined, bleached, and deodorised palm oil via transesterification using black pepper seed-KOH catalyst. A heterogeneous industrial waste catalyst, notably black pepper seed-KOH, was proposed because it can offer sustainability in biodiesel production. While among first generation oil feedstocks, palm oil stands out due to its high productivity because more palm oil can be generated per land area than others. Despite the most common use of the pseudo-first-order kinetic model in biodiesel studies, limited attention has been given to the second-order and reversible kinetics studies. Therefore, catalyst characterization encompassed SEM, EDX, TGA, PSA, FTIR, and basicity tests were first performed. Then, transesterification was executed at different temperatures (50–70 °C), 240-minute reaction time, 6:1 methanol-to-oil ratio, 5 wt% catalyst loading, and 200 rpm to obtain the best fit kinetic model and thermodynamic data. The results displayed a pseudo-irreversible first-order kinetics. Activation energy and pre-exponential factor were determined as 61.5195 kJ mol⁻¹ and 1.1367 × 107 min⁻¹. While, thermodynamic value was calculated, ΔH = 58.7528 kJ mol⁻¹, ΔS = − 0.0850 kJ mol⁻¹ K⁻¹ and ΔG = 86.2157 to 87.9162 kJ mol⁻¹. Therefore, the transesterification was defined as an endothermic, endogenic, and non-spontaneous reaction. This study demonstrates the black pepper seed-KOH’s efficacy in biodiesel production and enhances understanding of kinetic and thermodynamic parameters governing the transesterification process.

In this study, silver nanoparticles (Ag NPs) were synthesized in biogenic methods. It is aimed to improve the electrochemical sensor efficiency of synthesized Ag NPs against the pharmaceutical drug paracetamol. For this purpose, fourier transmission infrared spectroscopy (FTIR), ultra-violet visible spectroscopy (Uv–vis), X-ray differentiation (XRD), and transmission electron spectroscopy (TEM) analyses were performed to elucidate the structure of the synthesized Ag NPs. In the TEM characterization results, the mean size of the NPs was found to be 19.035 nm using TEM characterization and the XRD results, the crystalline size of the NPs was 11.66 nm. Sensor studies were performed with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Paracetamol showed a sensitivity of approximately 0.4 V to Ag NPs in this study. The linear ranges of this study are 6.5–14.5 µM, with a limit of detection (LOD) of 5.79 µM and a limit of quantification (LOQ) of 17.56 µM.