Optimized Preparation of Gold Nanoparticles-loaded Carbon Nanotubes (Au-CNTs) as an Efficient Catalyst for p-Nitrophenol Reduction

2021 ◽  
Vol 10 ◽  
Author(s):  
Farah Wahida Ahmad Zulkifli ◽  
Abdul Mutalib Md Jani ◽  
Hanani Yazid
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Aging Time ◽  
High Stability ◽  
Catalytic Efficiency ◽  
Precipitation Method ◽  
Synthesis Process ◽  
Order Kinetic ◽  
Nitrophenol Reduction ◽  
Nanocomposite Catalysts

Aim: The current work aims to enhance the catalytic performance of gold nanopar-ticle–carbon nanotube (Au-CNT) composites towards the reduction of p-nitrophenol. Background: The synthesis of Au-CNT has received extensive attention because of their high stability and catalytic efficiency, particularly as a heterogeneous catalyst in the reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) However, most of the Au-CNT preparation processes reported in the literature are time-consuming or require expensive instrumentation. In the present work, Au-CNT catalysts were synthesized via a straightforward, low-cost deposition–precipitation (DP) method. Objective: The aim of the study was to evaluate the effect of pH and aging time on catalytic activity of Au-CNTs catalyst. Method: The Au-CNT nanocomposite catalysts were synthesized using a simple deposition–precipitation method and characterized by Brunauer–Emmett–Teller analysis, fourier transform infrared spectroscopy, atomic absorption spectroscopy, thermogravimetric analysis, field emission scanning electron microscopy, and trans-mission electron microscopy. Results: The particle size and the loading of Au nanoparticles on the CNTs can be easily controlled by varying the pH and aging time during the synthesis process. The nanocomposite catalysts exhibited excellent catalytic activity for the reduction of p-nitrophenol to p-aminophenol in the presence of excess sodium borohydride (NaBH4). The highest rate constant (k) achieved based on the pseudo-first-order kinetic model was 1.2 × 10-3 s-1. Conclusion: This study offers a simple and cost-effective route to synthesize Au-CNT catalysts with high stability and catalytic efficiency for large-scale applica-tions.

scholarly journals Design and Characterization of Ag@Cu2O-rGO Nanocomposite for the p-Nitrophenol Reduction

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 43
Author(s):  
Chao Song ◽  
Shuang Guo ◽  
Lei Chen
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Catalytic Reduction ◽  
Catalytic Efficiency ◽  
Transmission Electron ◽  
Nitrophenol Reduction ◽  
Reduced Graphene ◽  
High Degree ◽  
Scanning Electron

In this paper, we designed Ag nanoparticles coated with a Cu2O shell, which was successfully decorated on reduced graphene oxide (rGO) via a solid-state self-reduction. The Cu2O, Ag@Cu2O, and Ag@Cu2O-rGO nanocomposites were synthesized and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis, and XPS to evaluate the properties of the composites. In order to compare the chemical catalytic activity, the Cu2O, Ag@Cu2O, and Ag@Cu2O-rGO nanocomposites were employed for the catalytic reduction of p-nitrophenol (4-NP) into p-aminophenol (4-AP) in aqueous solution. The Ag@Cu2O-rGO nanocomposite exhibited excellent catalytic activity due to the intense interaction and high degree of electron transfer among Ag, Cu2O, and rGO. The rGO acted as the platform to bridge the isolated nanoparticles; furthermore, the electrons could quickly transfer from the Ag core to the Cu2O shell, which improved the chemical catalytic efficiency.

scholarly journals Alkaline Modification of a Metal–Enzyme–Surfactant Nanocomposite to Enhance the Production of L-α-glycerylphosphorylcholine

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 237 ◽  
Author(s):  
Hui Li ◽  
Xun Cao ◽  
Yuanyuan Lu ◽  
Yan Ni ◽  
Xin Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Acyl Migration ◽  
Catalytic Efficiency ◽  
Biphasic System ◽  
Precipitation Method ◽  
Transmission Electron ◽  
Co Precipitation ◽  
Biphasic Systems

Microenvironment modification within nanoconfinement can maximize the catalytic activity of enzymes. Phospholipase A1 (PLA1) has been used as the biocatalyst to produce high value L-α-glycerylphosphorylcholine (L-α-GPC) through hydrolysis of phosphatidylcholine (PC). We successfully developed a simple co-precipitation method to encapsulate PLA1 in a metal–surfactant nanocomposite (MSNC), then modified it using alkalescent 2-Methylimidazole (2-Melm) to promote catalytic efficiency in biphasic systems. The generated 2-Melm@PLA1/MSNC showed higher catalytic activity than PLA1/MSNC and free PLA1. Scanning electron microscopy and transmission electron microscopy showed a typical spherical structure of 2-Melm@PLA1/MSNC at about 50 nm, which was smaller than that of 2-Melm@MSNC. Energy disperse spectroscopy, N2 adsorption isotherms, Fourier transform infrared spectrum, and high-resolution X-ray photoelectron spectroscopy proved that 2-Melm successfully modified PLA1/MSNC. The generated 2-Melm@PLA1/MSNC showed a high catalytic rate per unit enzyme mass of 1.58 μmol mg-1 min-1 for the formation of L-α-GPC. The 2-Melm@PLA1/MSNC also showed high thermal stability, pH stability, and reusability in a water–hexane biphasic system. The integration of alkaline and amphiphilic properties of a nanocomposite encapsulating PLA1 resulted in highly efficient sequenced reactions of acyl migration and enzymatic hydrolysis at the interface of a biphasic system, which cannot be achieved by free enzyme.

Synthesis of Ni@MWCNTs Magnetic Nanocatalysts and their Catalytic Activity towards 4-Nitrophenol Reduction

2012 ◽  
Vol 531 ◽  
pp. 358-361 ◽  
Author(s):  
Ming Mei Zhang ◽  
Qian Sun ◽  
Ji Min Xie
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
Average Particle Size ◽  
Chemical Vapor ◽  
High Catalytic Activity ◽  
Average Particle ◽  
Ni Nanoparticles ◽  
Nitrophenol Reduction ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

A well-dispersed Ni nanoparticles on multi-walled carbon nanotubes (Ni@MWCNTs) was prepared by chemical vapor deposition (CVD) method using a vacuum quartz tube furnace at the temperature of 600°C. The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were performed to characterize the synthesized catalyst. It shows an unfirom dispersion of Ni nanoparticles on MWCNTs with the average particle size of 8.6 nm. The as synthesized catalyst was applied in a redox reaction of 4-nitrophenol, which showed very high catalytic activity, stability and well conversion. The catalyst can be easily separated due to the magnetical performance

scholarly journals Investigation on Variables Contributing to the Synthesis of C-S-H/PCE Nanocomposites by Co-Precipitation Method

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7673
Author(s):  
Ziyang You ◽  
Jing Xu
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Precipitation Method ◽  
Synthesis Process ◽  
Orthogonal Experimental Design ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Ultra Fine Particle ◽  
Early Performance ◽  
Co Precipitation

The usage of nanoscale calcium silicate hydrate (nano C-S-H) proved to have an excellent promotion effect on the early performance of concrete as nano C-S-H with ultra-fine particle size can act as seeding for cement hydration. Therefore, it is of importance to tune the particle size during the synthesis process of nano C-S-H. In this paper, the influence of several variables of the particle size distribution (PSD) of nano C-S-H synthesized by chemical co-precipitation method with the aid of polycarboxylate (PCE) was studied by orthogonal experimental design. In addition, the composition, microstructure, and morphology of the C-S-H/PCE nanocomposites were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectrum. The results showed that the concentration of reactants had a significant impact on the PSD of C-S-H/PCE nanocomposites, followed by the dosage of dispersant. Ultrasonic treatment was effective in breaking the C-S-H/PCE aggregates with unstable agglomeration structures. The change in synthetic variables had a negligible effect on the composition of the C-S-H/PCE nanocomposites but had a significant influence on the crystallinity and morphology of the composites.

scholarly journals Kinetic Studies on the Catalytic Degradation of Rhodamine B by Hydrogen Peroxide: Effect of Surfactant Coated and Non-Coated Iron (III) Oxide Nanoparticles

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2246
Author(s):  
Mohd Shaban Ansari ◽  
Kashif Raees ◽  
Moonis Ali Khan ◽  
M.Z.A. Rafiquee ◽  
Marta Otero
Keyword(s):  
Electron Microscopy ◽  
Hydrogen Peroxide ◽  
Rhodamine B ◽  
Sodium Dodecyl ◽  
Kinetic Studies ◽  
Catalytic Degradation ◽  
Precipitation Method ◽  
Order Kinetic ◽  
Fe3o4 Nps ◽  
Co Precipitation

Iron (III) oxide (Fe3O4) and sodium dodecyl sulfate (SDS) coated iron (III) oxide (SDS@Fe3O4) nanoparticles (NPs) were synthesized by the co-precipitation method for application in the catalytic degradation of Rhodamine B (RB) dye. The synthesized NPs were characterized using X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infra-red (FT-IR) spectroscopy techniques and tested in the removal of RB. A kinetic study on RB degradation by hydrogen peroxide (H2O2) was carried out and the influence of Fe3O4 and SDS@Fe3O4 magnetic NPs on the degradation rate was assessed. The activity of magnetic NPs, viz. Fe3O4 and SDS@Fe3O4, in the degradation of RB was spectrophotometrically studied and found effective in the removal of RB dye from water. The rate of RB degradation was found linearly dependent upon H2O2 concentration and within 5.0 × 10−2 to 4.0 × 10−1 M H2O2, the observed pseudo-first-order kinetic rates (kobs, s−1) for the degradation of RB (10 mg L−1) at pH 3 and temperature 25 ± 2 °C were between 0.4 and 1.7 × 104 s−1, while in presence of 0.1% w/v Fe3O4 or SDS@Fe3O4 NPs, kobs were between 1.3 and 2.8 × 104 s−1 and between 2.6 and 4.8 × 104 s−1, respectively. Furthermore, in presence of Fe3O4 or SDS@Fe3O4, kobs increased with NPs dosage and showed a peaked pH behavior with a maximum at pH 3. The magnitude of thermodynamic parameters Ea and ΔH for RB degradation in presence of SDS@Fe3O4 were 15.63 kJ mol−1 and 13.01 kJ mol−1, respectively, lowest among the used catalysts, confirming its effectiveness during degradation. Furthermore, SDS in the presence of Fe3O4 NPs and H2O2 remarkably enhanced the rate of RB degradation.

scholarly journals Crystallographic studies through HRTEM and XRD of MoS2nanostructures

2014 ◽  
Vol 70 (a1) ◽  
pp. C512-C512
Author(s):  
Eric Rivera-Muñoz ◽  
Rafael Huirache-Acuña ◽  
Beatriz Millán-Malo ◽  
Rufino Nava ◽  
Barbara Pawelec ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Nanostructured Materials ◽  
Synthesis Process ◽  
X Ray ◽  
Transmission Electron ◽  
Sulfided Catalysts ◽  
Hds Catalysts

Mesoporous and silica-based SBA-15 and SBA-16 materials were used as supports of novel nanostructured ternary Co(Ni)-Mo-W hydrodesulphurization (HDS) catalysts. These materials have shown a high catalytic activity in HDS of dibenzothiophene (DBT) reactions, even much higher compared with commercial catalysts. An exploration was made on the structure of both the supports as well as on tri-metallic sulfide HDS catalysts. The sulfided catalysts were tested in the HDS of DBT performed in a batch reactor at 623 K and total pressure of 3.1 MPa. The calcined and fresh sulfide catalysts were characterized by a variety of techniques, such as N2 adsorption-desorption isotherms, Temperature-Programmed Desorption (TPD) of NH3, X-ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). It has been found that both the morphology of the supports as its modification with varying amounts of phosphorus affect the catalytic activity of these nanostructured materials in HDS of DBT reactions. Furthermore, the nanostructures which correspond to the tri-metallic sulfided catalysts exhibit a typical morphology of MoS2 – 2H structure. The present work shows the microstructural study of these nanostructured materials, carried out from HRTEM images and XRD analysis. Both techniques, X–ray Diffractometry and High Resolution Transmission Electron Microscopy, play a fundamental role in the characterization of the microstructure of HDS catalytic nanomaterials, as well as in understanding the various phenomena involved, starting from the synthesis process unto the final performance of those materials.

Optimization of the Process Parameters for the Synthesis Process of Battery-Grade Ferrous Oxalate by Response Surface Method

NANO ◽  
2016 ◽  
Vol 11 (11) ◽  
pp. 1650123 ◽  
Author(s):  
Keyu Zhang ◽  
Xiaoyan Yang ◽  
Jian Wu ◽  
Xiaopeng Huang ◽  
Yaochun Yao
Keyword(s):  
Particle Size ◽  
Aging Time ◽  
Reaction Temperature ◽  
Ferrous Sulfate ◽  
Raw Material ◽  
Precipitation Method ◽  
Synthesis Process ◽  
Preparation Conditions ◽  
Ferrous Oxalate ◽  
Crystallographic Planes

This study investigates the optimal conditions for the synthesis of battery-grade ferrous oxalate as a raw material for preparing cathode material. Ferrous oxalate was prepared by liquid-phase precipitation method using ferrous sulfate and oxalic acid. Central composite design (CCD) was used to determine the effects of three preparation variables on purity and particle size: reaction temperature, aging time and concentration of ferrous sulfate. Based on CCD, the significant factors on each experimental design response identified the analysis of variance (ANOVA). The optimum ferrous oxalate preparation conditions were obtained reaction temperature of 31.32[Formula: see text]C, aging time of 56.52[Formula: see text]min, and ferrous sulfate concentration of 5%. Under these optimum conditions, ferrous oxalate with purity of 99.69% and particle size of 4.92[Formula: see text][Formula: see text]m was obtained as best product which met and exceed the requirements of battery-grade ferrous oxalate. In addition, the special morphologies of ferrous oxalate prepared under different dispersant proportion was characterized by scanning electron microscope (SEM) to analyze the mechanism of synthesis. Morphology control study revealed that the dispersant could effectively change the surface energy between crystallographic planes, then result in anisotropic growth of the crystal structure and change the morphology of synthetic products.

scholarly journals Silicone Nanofilament Support Layers in an Open-Channel System for the Fast Reduction of Para-Nitrophenol

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1663
Author(s):  
Noah U. Naef ◽  
Stefan Seeger
Keyword(s):  
Electron Microscopy ◽  
Open Channel ◽  
Chemical Vapor ◽  
Catalytic Efficiency ◽  
Catalytic Performance ◽  
Metal Catalyst ◽  
Surface Tension Gradient ◽  
Channel System ◽  
Transition Electron Microscopy ◽  
Nitrophenol Reduction

Chemical vapor phase deposition was used to create hydrophobic nanostructured surfaces on glass slides. Subsequently, hydrophilic channels were created by sputtering a metal catalyst on the channels while masking the outside. The surface tension gradient between the hydrophilic surface in the channels and the outside hydrophobicity formed the open-channel system. The reduction of para-nitrophenol (PNP) was studied on these devices. When compared to nanostructure-free reference systems, the created nanostructures, namely, silicone nanofilaments (SNFs) and nano-bagels, had superior catalytic performance (73% and 66% conversion to 55% at 0.5 µL/s flow rate using 20 nm platinum) and wall integrity; therefore, they could be readily used multiple times. The created nanostructures were stable under the reaction conditions, as observed with scanning electron microscopy. Transition electron microscopy studies of platinum-modified SNFs revealed that the catalyst is present as nanoparticles ranging up to 13 nm in size. By changing the target in the sputter coating unit, molybdenum, gold, nickel and copper were evaluated for their catalytic efficiency. The relative order was platinum < gold = molybdenum < nickel < copper. The decomposition of sodium borohydride (NaBH4) by platinum as a concurrent reaction to the para-nitrophenol reduction terminates the reaction before completion, despite a large excess of reducing agent. Gold had the same catalytic rate as molybdenum, while nickel was two times and copper about four times faster than gold. In all cases, there was a clear improvement in catalysis of silicone nanofilaments compared to a flat reference system.

Surface texture and physicochemical characterization of mesoporous carbon – wrapped Pd–Fe catalysts for low-temperature CO catalytic oxidation

2015 ◽  
Vol 17 (43) ◽  
pp. 29027-29035 ◽  
Author(s):  
Weiliang Han ◽  
Guodong Zhang ◽  
Kun Zhao ◽  
Gongxuan Lu ◽  
Zhicheng Tang
Keyword(s):  
Catalytic Activity ◽  
Mesoporous Carbon ◽  
Physicochemical Characterization ◽  
Precipitation Method ◽  
Experimental Conditions ◽  
Co Catalytic Oxidation ◽  
Fe Catalysts ◽  
Nanocomposite Catalysts ◽  
Co Precipitation

In this paper, mesoporous carbon wrapped Pd–Fe nanocomposite catalysts were synthesized by the co-precipitation method and showed excellent catalytic activity, after optimizing the experimental conditions.

Effect of Stirring and Aging Time on the Formation of β-Tricalcium Phosphate (β-TCP) Powder

2016 ◽  
Vol 840 ◽  
pp. 156-159
Author(s):  
Shah Rizal Kasim ◽  
Siti Noor Fazliah Mohd Noor ◽  
Zainal Arifin Ahmad
Keyword(s):  
Electron Microscopy ◽  
Aging Time ◽  
Tricalcium Phosphate ◽  
Calcium Nitrate ◽  
Xrd Analysis ◽  
Precipitation Method ◽  
Calcium Nitrate Tetrahydrate ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Nitrate Tetrahydrate

In this research, the effect of stirring and aging time on the formation of β-tricalcium phosphate (β-TCP) powder was studied. β-TCP powder was synthesized using calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) (0.6M) and diammonium hydrogen phosphate (NH4)2HPO4) (0.4M) via wet precipitation method. The mixture was stirred with different duration (1, 3, 5 and 7 hours) then centrifuged before washed with distilled water (twice) and ethanol followed by drying in oven (80°C, 24 hours). The cake was ground to form powder. The as prepared powder was analyzed using thermo-gravimetric (TGA) to determine the suitable calcinations temperature. TGA results show that the proper calcinations temperature was 800°C. The formation of β-TCP was characterized using X-ray Diffraction (XRD) analysis. Sample with optimum formation of β-TCP phase will choose for further study on the effect of aging time (0.5, 1, 20 and 24 hours). XRD analysis confirmed that sample stirred for 7 hours and aging for 24 hours produced β-TCP as major phase. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) proved that β-TCP powder form as agglomerated particles

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