scholarly journals Reaction Parameters for Controlled Sonosynthesis of Gold Nanoparticles

2017 ◽  
Vol 59 (2) ◽  
Author(s):  
Lourdes I. Cabrera-Lara
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Reaction Temperature ◽  
Ostwald Ripening ◽  
Nanoparticle Synthesis ◽  
Particle Morphology ◽  
Reducing Agent ◽  
Reaction Parameters ◽  
Sodium Tartrate ◽  
Sonochemical Reaction

The synthesis of gold nanoparticles by sonochemical technique has been previously performed with excellent results. The synthesis has been carried out in the presence of citric acid, a strong reducing agent, which allows the nucleation and growth of gold nanoparticles, at the same time that controls particle size. In this work, we report the use of sodium tartrate as a mild reducing agent that allows a better understanding of the effect of the reaction parameters during gold nanoparticle synthesis. A conventional sonication bath (37 kHz) was used for the sonochemical synthesis. This work focuses on the reaction temperature effect and the effect of sodium tartrate concentration. It was confirmed that particle size, and particle morphology is dependent of these two reaction parameters. Equally, colloidal stabilization was related to reaction temperature and sodium tartrate concentration. It was also determined that Ostwald ripening takes place during sonochemical reaction under our conditions, allowing us to understand the mechanism that takes place during synthesis. Gold nanoparticles with main particle size of 17 nm were achieved by this method.

Controlled Growth of Gold Nanoparticles on Silica Nanowires

2005 ◽  
Vol 20 (11) ◽  
pp. 3021-3027 ◽  
Author(s):  
Aaron D. LaLonde ◽  
M. Grant Norton ◽  
Daqing Zhang ◽  
Devananda Gangadean ◽  
Abdullah Alkhateeb ◽  
...  
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Substrate Temperature ◽  
Size Distribution ◽  
Surface Diffusion ◽  
Ostwald Ripening ◽  
Size Control ◽  
Chemical Vapor ◽  
Chamber Pressure ◽  
Transmission Electron

Production of gold nanoparticles with the specific goal of particle size control has been investigated by systematic variation of chamber pressure and substrate temperature. Gold nanoparticles have been synthesized on SiO2 nanowires by plasma-enhanced chemical vapor deposition. Determination of particle size and particle size distribution was done using transmission electron microscopy. Average nanoparticle diameters were between 4 and 12 nm, with particle size increasing as substrate temperature increased from 573 to 873 K. A bimodal size distribution was observed at temperatures ≥723 K indicating Ostwald ripening dominated by surface diffusion. The activation energy for surface diffusion of gold on SiO2 was determined to be 10.4 kJ/mol. Particle sizes were found to go through a maximum with increases in chamber pressure. Competition between diffusion within the vapor and dissociation of the precursor caused the pressure effect.

scholarly journals Continuous flow synthesis of citrate capped gold nanoparticles using UV induced nucleation

RSC Advances ◽  
2017 ◽  
Vol 7 (16) ◽  
pp. 9632-9638 ◽  
Author(s):  
H. du Toit ◽  
T. J. Macdonald ◽  
H. Huang ◽  
I. P. Parkin ◽  
A. Gavriilidis
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Gold Nanoparticle ◽  
Continuous Flow ◽  
Nanoparticle Synthesis ◽  
Nucleation And Growth ◽  
Reactor System ◽  
Growth Phases ◽  
Flow Synthesis ◽  
Gold Nanoparticle Synthesis

A novel multimodal reactor system for separating the nucleation and growth phases of gold nanoparticle synthesis to control particle size.

THE MANUFACTURING OF NIOBIUM POWDER BY HUNTER PROCESS

2010 ◽  
Vol 17 (02) ◽  
pp. 223-228
Author(s):  
JAE-SIK YOON
Keyword(s):  
Particle Size ◽  
Reaction Temperature ◽  
Average Particle Size ◽  
Reduction Process ◽  
Reducing Agent ◽  
Raw Material ◽  
Average Particle ◽  
Metallothermic Reduction ◽  
Niobium Powder ◽  
Yield Rate

Niobium powder was fabricated by metallothermic reduction process using K2NbF7 as the raw material, KCl and KF as the diluents and Na as the reducing agent. The apparatus for the experiment was designed and built specifically for the present study. Varying properties of niobium powder depending on reaction temperature and excess of reducing agent were analyzed. The niobium particle size increased significantly as the reduction temperature increased from 993 to 1093 K. The particle size was fairly uniform at a given reaction temperature, varying from 0.2 μ m to 50 nm depending on the reaction temperature. The yield of niobium powder increased from 58 to 83% with an increase in reaction temperature. The average particle size of niobium powder was improved from 70 nm to 0.2 μ m with the increase in the amount of Na excess. In addition, the yield rate of Nb powder was 82% in the 5% excess sodium.

Analysis by response surface methodology of gold nanoparticles obtained by green chemical reduction using aqueous coffee pulp extract (Coffea arabica)

2021 ◽  
Author(s):  
Galileo Bonilla-Nepomuceno ◽  
Maria Antonieta Rios-Corripio ◽  
Fernando C. Gomez-Merino ◽  
Miguel Angel Mendez-Rojas ◽  
Leslie Susana Arcila-Lozano ◽  
...  
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Coffea Arabica ◽  
Response Surfaces ◽  
Reducing Agent ◽  
Therapeutic Area ◽  
Coffee Pulp ◽  
Wide Range

Green synthesis of gold nanoparticles using an aqueous coffee (<i>Coffea arabica</i>) pulp extract as a reducing agent was achieved and analyzed by response surface methodology, given the diverse applicability of these nanoparticles containing a wide range of phenolic compounds from the coffee pulp extract. Three factors (precursor concentration, reducing agent concentration, and reaction time) were considered and their combined effects on the maximum intensity (<i>MA</i>), particle size (<i>d</i>), and particle density (<i>N</i>) were analyzed. An opposing effect between the precursor and reducing agent was observed during synthesis because while the precursor increased <i>d</i> and diminished <i>N</i>, the reducing agent diminished <i>d</i> and increased <i>N</i>. These effects were observed simultaneously through the response surfaces of <i>d</i> and <i>N</i>. This methodology allowed the synthesis of nanoparticles with an average particle size between 5–22 nm and <i>N</i> around 2.9x10<sup>11</sup>−3.7x10<sup>13</sup> (part/mL), depending on the response surface methodology, Box-Behnken design. The R<sup>2</sup> value determined for all cases was 0.98 (<i>MA</i>), 0.99 (<i>d</i>), and 0.97 (<i>N</i>), clearly indicating that the model can be used to predict or design the response variables in the design space. Finally, Fourier transform infrared measurements showed that the organic compounds present in the aqueous coffee pulp extract were coating the surface of the gold nanoparticles. The proposed methodology could contribute to the design of new alternatives for the synthesis of specific nanostructures with potential applications in the therapeutic area.

Surface energy of cellulosic materials: The effect of particle morphology, particle size, and hydroxyl number

TAPPI Journal ◽  
2015 ◽  
Vol 14 (9) ◽  
pp. 565-576 ◽  
Author(s):  
YUCHENG PENG ◽  
DOUGLAS J. GARDNER
Keyword(s):  
Particle Size ◽  
Surface Energy ◽  
Particle Morphology ◽  
Nanofibrillated Cellulose ◽  
Particle Sizes ◽  
Hydroxyl Number ◽  
Small Individual ◽  
Dispersion Component ◽  
Commercial Applications ◽  
Lower Temperature

Understanding the surface properties of cellulose materials is important for proper commercial applications. The effect of particle size, particle morphology, and hydroxyl number on the surface energy of three microcrystalline cellulose (MCC) preparations and one nanofibrillated cellulose (NFC) preparation were investigated using inverse gas chromatography at column temperatures ranging from 30ºC to 60ºC. The mean particle sizes for the three MCC samples and the NFC sample were 120.1, 62.3, 13.9, and 9.3 μm. The corresponding dispersion components of surface energy at 30°C were 55.7 ± 0.1, 59.7 ± 1.3, 71.7 ± 1.0, and 57.4 ± 0.3 mJ/m2. MCC samples are agglomerates of small individual cellulose particles. The different particle sizes and morphologies of the three MCC samples resulted in various hydroxyl numbers, which in turn affected their dispersion component of surface energy. Cellulose samples exhibiting a higher hydroxyl number have a higher dispersion component of surface energy. The dispersion component of surface energy of all the cellulose samples decreased linearly with increasing temperature. MCC samples with larger agglomerates had a lower temperature coefficient of dispersion component of surface energy.

Nanostructured Polymetallic Powders to Create New Functional Materials on its Base

2015 ◽  
Vol 670 ◽  
pp. 49-54 ◽  
Author(s):  
Yuriy A. Zaharov ◽  
Valeriy M. Pugachev ◽  
Kseniya A. Datiy ◽  
Anna N. Popova ◽  
Anastasiya S. Valnyukova ◽  
...  
Keyword(s):  
Particle Size ◽  
Phase Diagrams ◽  
Spatial Organization ◽  
Functional Materials ◽  
Particle Morphology ◽  
Cloud Type ◽  
Synthesis Conditions ◽  
Micron Size ◽  
Common Nature ◽  
20 Nm

In the paper, the particle morphology is considered and the slices of phase diagrams of nanosystems agreeable to the synthesis conditions are constructed according to the data obtained earlier by authors, as well as new results of the study of nanostructured Fe-Co, Fe-Ni, Co-Ni, Fe-Co-Ni, Fe-Pt, Cu-Ni and Ni-Cd powders. It is found that all considered polymetallic systems have common nature of the particle size spatial organization, i.e., 7-20 nm nanocrystals (for different systems) form highly compact aggregates (40-100 nm) which put together into loose porous agglomerates (up to 200-250 nm) and then into unconsolidated micron size formation of cloud type. It is classified uncovered features of nanostructured polymetallic phase diagrams in comparison with phase diagrams of bulk systems. Magnetic properties of nanosystems are studied.

scholarly journals Continuous citrate‐capped gold nanoparticle synthesis in a two‐phase flow reactor

2021 ◽  
Author(s):  
Spyridon Damilos ◽  
Ioannis Alissandratos ◽  
Luca Panariello ◽  
Anand N. P. Radhakrishnan ◽  
Enhong Cao ◽  
...  
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Residence Time ◽  
Flow Reactor ◽  
Phase Flow ◽  
Continuous Manufacturing ◽  
Two Phase ◽  
Process Yield ◽  
Au Nps ◽  
Manufacturing Platform

AbstractA continuous manufacturing platform was developed for the synthesis of aqueous colloidal 10–20 nm gold nanoparticles (Au NPs) in a flow reactor using chloroauric acid, sodium citrate and citric acid at 95 oC and 2.3 bar(a) pressure. The use of a two-phase flow system – using heptane as the continuous phase – prevented fouling on the reactor walls, while improving the residence time distribution. Continuous syntheses for up to 2 h demonstrated its potential application for continuous manufacturing, while live quality control was established using online UV-Vis photospectrometry that monitored the particle size and process yield. The synthesis was stable and reproducible over time for gold precursor concentration above 0.23 mM (after mixing), resulting in average particle size between 12 and 15 nm. A hydrophobic membrane separator provided successful separation of the aqueous and organic phases and collection of colloidal Au NPs in flow. Process yield increased at higher inlet flow rates (from 70 % to almost 100 %), due to lower residence time of the colloidal solution in the separator resulting in less fouling in the PTFE membrane. This study addresses the challenges for the translation of the synthesis from batch to flow and provides tools for the development of a continuous manufacturing platform for gold nanoparticles.Graphical abstract

scholarly journals Continuous synthesis of gold nanoparticles in micro- and millifluidic systems

2018 ◽  
Vol 6 (3) ◽  
Author(s):  
He Huang ◽  
Hendrik du Toit ◽  
Luca Panariello ◽  
Luca Mazzei ◽  
Asterios Gavriilidis
Keyword(s):  
Gold Nanoparticles ◽  
Nanoparticle Synthesis ◽  
Reactor Operation ◽  
Design Procedures ◽  
Time Control ◽  
Starting Point ◽  
Quantitative Understanding ◽  
Gold Nanomaterials ◽  
Gold Nanoparticle Synthesis ◽  
Flow Devices

Abstract Gold nanomaterials have diverse applications ranging from healthcare and nanomedicine to analytical sciences and catalysis. Microfluidic and millifluidic reactors offer multiple advantages for their synthesis and manufacturing, including controlled or fast mixing, accurate reaction time control and excellent heat transfer. These advantages are demonstrated by reviewing gold nanoparticle synthesis strategies in flow devices. However, there are still challenges to be resolved, such as reactor fouling, particularly if robust manufacturing processes are to be developed to achieve the desired targets in terms of nanoparticle size, size distribution, surface properties, process throughput and robustness. Solutions to these challenges are more effective through a coordinated approach from chemists, engineers and physicists, which has at its core a qualitative and quantitative understanding of the synthesis processes and reactor operation. This is important as nanoparticle synthesis is complex, encompassing multiple phenomena interacting with each other, often taking place at short timescales. The proposed methodology for the development of reactors and processes is generic and contains various interconnected considerations. It aims to be a starting point towards rigorous design procedures for the robust and reproducible continuous flow synthesis of gold nanoparticles. Graphical Abstract:

scholarly journals Enhanced Extracellular Synthesis of Gold Nanoparticles by Soluble Extracts from Escherichia coli Transformed with Rhizobium tropici Phytochelatin Synthase Gene

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 472
Author(s):  
Qunying Yuan ◽  
Manjula Bomma ◽  
Zhigang Xiao
Keyword(s):  
Gold Nanoparticles ◽  
Gold Nanoparticle ◽  
Synthesis Method ◽  
Nanoparticle Synthesis ◽  
Morphological Properties ◽  
Phytochelatin Synthase ◽  
Rhizobium Tropici ◽  
Whole Cells ◽  
E Coli ◽  
Recombinant Cells

Phytochelatins, the enzymatic products of phytochelatin synthase, play a principal role in protecting the plants from heavy metal and metalloid toxicity due to their ability to scavenge metal ions. In the present study, we investigated the capacity of soluble intracellular extracts from E. coli cells expressing R. tropici phytochelatin synthase to synthesize gold nanoparticle. We discovered that the reaction mediated by soluble extracts from the recombinant E. coli cells had a higher yield of gold nanoparticles, compared to that from the control cells. The compositional and morphological properties of the gold nanoparticles synthesized by the intracellular extracts from recombinant cells and control cells were similar. In addition, this extracellular nanoparticle synthesis method produced purer gold nanoparticles, avoiding the isolation of nanoparticles from cellular debris when whole cells are used to synthesize nanoparticles. Our results suggested that phytochelatins can improve the efficiency of gold nanoparticle synthesis mediated by bacterial soluble intracellular extracts, and the potential of extracellular nanoparticle synthesis platform for the production of nanoparticles in large quantity and pure form is worth further investigation.

Hydrogen Generation by Hydrolysis of the Ball Milled Al-C-KCl Composite Powder in Distilled Water

2012 ◽  
Vol 519 ◽  
pp. 87-91 ◽  
Author(s):  
Xia Ni Huang ◽  
Zhang Han Wu ◽  
Ke Cao ◽  
Wen Zeng ◽  
Chun Ju Lv ◽  
...  
Keyword(s):  
Particle Size ◽  
Reaction Temperature ◽  
Fine Particle ◽  
Composite Powder ◽  
Hydrogen Generation ◽  
Aluminum Particle ◽  
Generation Rate ◽  
Composite Powders ◽  
Fine Particle Size ◽  
Hydrolysis Of

In the present investigation, the Al-C-KCl composite powders were prepared by a ball milling processing in an attempt to improve the hydrogen evolution capacity of aluminum in water. The results showed that the hydrogen generation reaction is affected by KCl amount, preparation processing, initial aluminum particle size and reaction temperature. Increasing KCl amount led to an increased hydrogen generation volume. The use of aluminum powder with a fine particle size could promote the aluminum hydrolysis reaction and get an increased hydrogen generation rate. The reaction temperature played an important role in hydrogen generation rate and the maximum hydrogen generation rate of 44.8 cm3 min-1g-1of Al was obtained at 75oC. The XRD results identified that the hydrolysis byproducts are bayerite (Al(OH)3) and boehmite (AlOOH).

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