scholarly journals Supercritical hydrothermal synthesis of silver nanoparticles, composites, and their characterizations

2021 ◽  
Vol 22 (48) ◽  
pp. 25-30
Author(s):  
Narandalai Byamba-ochir ◽  
Nemekhbayar Davaadorj ◽  
Battseveen Buyankhishig ◽  
Enkhtuul Surenjav
Keyword(s):  
Silver Nanoparticles ◽  
Activated Carbon ◽  
Composite Materials ◽  
Supercritical Water ◽  
Hydrothermal Process ◽  
Synthesis Method ◽  
Precursor Solution ◽  
Carbon Surface ◽  
Silver Particles ◽  
Synthesis Time

Silver nanoparticles (AgNPs) and silver nanoparticles doped activated carbon (AC-Ag) composite materials were synthesized by hydrothermal processes in supercritical water conditions (29 MPa and 400 °C) using batch reactor. We studied the influence of the precursor solution concentration, reaction temperature under the hydrothermal conditions, and synthesis time on the properties of synthesized materials. The properties of plain AgNPs and AC-Ag composite materials synthesized in supercritical water, including crystallinity, particle size, and molecular interactions between AC and Ag were investigated, comprehensively. Compared to the plain AgNPs, the activated carbon-supported Ag nanocomposite was synthesized faster due to the active functional groups of activated carbon. Furthermore, the FTIR results reveal that the silver nanoparticles are attached to the activated carbon surface in the presence of oxygen bonded carbonyl and carboxyl groups. The nano-sized metal silver particles were observed on the AC surface when analyzed by TEM and XRD. All results imply that the supercritical water condition allows the formation of silver particles less than 100 nm either in the form of plain particles or deposited on the activated carbon surface using the silver acetate precursor solution. This environmentally benign supercritical hydrothermal process can replace the conventional method and become a novel synthesis method for preparing various new materials.

Synthesis of Silver Nanoparticles by Hydrothermal Processing

2021 ◽  
Vol 323 ◽  
pp. 1-7
Author(s):  
Enkhtuul Surenjav ◽  
Battseveen Buyankhishig ◽  
Narandalai Byamba-Ochir ◽  
Nemekhbayar Davaadorj ◽  
Zhi Qiang Song ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Supercritical Water ◽  
Batch Reactor ◽  
Acetate Solution ◽  
Silver Acetate ◽  
Silver Particles ◽  
Uniform Size ◽  
Low Dielectric ◽  
Water Treatments ◽  
Hydrothermal Water

Hydrothermal water treatments of silver acetate (CH3COOAg) were investigated to reveal the factors controlling the formation of silver nanoparticles (AgNPs) with uniform size distribution. The effects of reaction time and concentration of silver acetate solution on the synthesis of Ag nanoparticles were studied, and the fabricated products were characterized. The hydrothermal water treatments of CH3COOAg were carried out between the temperatures of 250 - 450 °C in a batch reactor. In supercritical water regions, at 400 °C and a pressure of 31.5 MPa, silver particles are rapidly synthesized due to reaction rate increases at a low dielectric constant of supercritical water. The preparation of the silver particles with 30-80 nm in size showed a highly crystalline structure identified by XRD and TEM observations.

scholarly journals Comparison Study of Adsorption of Lead and Methylene Blue on Zeolite, Activated Carbon and Their Composite Materials

2019 ◽  
Vol 25 (8) ◽  
pp. 129-148
Author(s):  
Rafie Rushdy Mohammed
Keyword(s):  
Aqueous Solution ◽  
Methylene Blue ◽  
Activated Carbon ◽  
Composite Materials ◽  
Synthesis Method ◽  
Nitrogen Adsorption ◽  
Batch Mode ◽  
Thermally Activated ◽  
Optimum Synthesis ◽  
Pseudo Second Order

In this study, composite materials consisting of Activated Carbon (AC) and Zeolite were prepared for application in the removal of methylene blue and lead from an aqueous solution. The optimum synthesis method involves the use of metakaolinization and zeolitization, in the presence of activated carbon from kaolin, to form Zeolite. First, Kaolin was thermally activated into amorphous kaolin (metakaolinization); then the resultant metakaolin was attacked by alkaline, transforming it into crystalline zeolite (zeolitization). Using nitrogen adsorption and SEM techniques, the examination and characterization of composite materials confirmed the presence of a homogenous distribution of Zeolite throughout the activated carbon. It has also shown the carbonization process did not destroy the crystalline structure of the zeolite, which was revealed to be intact. Experiments in batch mode were conducted (using three differently-prepared composites, zeolite and activated carbon), to investigate the removal of methylene blue and lead from the aqueous solution of the sorbents. Key experimental parameters (initial concentration, pH, contact time and adsorbent dosage) from the obtained results were measured and analysed. Freundlich and Langmuir models were used to describe the adsorption isotherms, and the observed adsorption kinetic adhered to pseudo-second order.  

scholarly journals Scalable Electrochemical Synthesis of Novel Biogenic Silver Nanoparticles and Its Application to High-Sensitive Detection of 4-Nitrophenol in Aqueous System

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Van-Tuan Hoang ◽  
Ngo Xuan Dinh ◽  
Tuyet Nhung Pham ◽  
Tran Vinh Hoang ◽  
Pham Anh Tuan ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Electrochemical Properties ◽  
Electrochemical Synthesis ◽  
Large Scale ◽  
Scale Up ◽  
Synthesis Method ◽  
Aqueous System ◽  
Carbon Surface ◽  
Voltage Source ◽  
Biogenic Silver Nanoparticles

This study reports a scalable green electrochemical synthesis of novel biogenic silver nanoparticles colloid (biogenic AgNPs) in large scale up to 5 liters using the bulk silver bar and the green tea leaves (Camellia sinensis) extract (GTE) as reducing agent during the electrochemical process. Under a direct-current voltage source, the biomolecules in GTE can release electrons to promote the reducing process of Ag+ to Ag0. More interestingly, the formation of the intermediate complex helps to cap on the nanoparticles, which leads to stabilizing AgNPs. The as-synthesized biogenic AgNPs with the size of 34 nm exhibit the outstanding electrochemical properties due to the presence of biomolecules on the biogenic AgNPs surface, which facilitates the effective attaching of AgNPs on the carbon surface of the screen-printed carbon electrode (SPE) through the formation of the strong C-O coordinate bonds between O atom of oxygen functional groups and C atom of SPE. The electrochemical properties of the biogenic AgNPs-modified SPE are enhanced significantly in comparison with bare SPE and pure AgNPs-SPE. The biogenic AgNPs-SPE is applied successfully to the detection of 4-nitrophenol (4-NP). The electrochemical sensor using biogenic AgNPs can reliably detect 4-NP in the linear range from 0.1 to 25 μM with the sensitivity about 6.69 μA μM-1 cm-2. The present work reveals, as the greener synthesis method with ultra-large scalable ability, high purity, and excellent electrochemical properties of biogenic AgNPs is very promising for technological applications in high-sensitive electrochemical chemosensors, nanopharmaceuticals, and other fields.

scholarly journals Protocol optimization for a fast, simple and economical chemical reduction synthesis of antimicrobial silver nanoparticles in non-specialized facilities

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Roberto Vazquez-Muñoz ◽  
M. Josefina Arellano-Jimenez ◽  
Fernando D. Lopez ◽  
Jose L. Lopez-Ribot
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Chemical Reduction ◽  
Nitrate Solution ◽  
Synthesis Method ◽  
Reduction Process ◽  
Cost Effective ◽  
Silver Nitrate Solution ◽  
Synthesis Time ◽  
Average Size

Abstract Objective Silver nanoparticles (AgNPs) can be difficult or expensive to obtain or synthesize for laboratories in resource-limited facilities. The purpose of this work was to optimize a synthesis method for a fast, facile, and cost-effective synthesis of AgNPs with antimicrobial activity, which can be readily implemented in non-specialized facilities and laboratories. Results The optimized method uses a rather simple and rapid chemical reduction process that involves the addition of a polyvinylpyrrolidone solution to a warmed silver nitrate solution under constant vigorous stirring, immediately followed by the addition of sodium borohydride. The total synthesis time is less than 15 min. The obtained AgNPs exhibit an aspect ratio close to 1, with an average size of 6.18 ± 5 nm. AgNPs displayed potent antimicrobial activity, with Minimal Inhibitory Concentration values of ≤ 4 µg mL−1 for Staphylococcus aureus and ≤ 2 µg mL−1 for Candida albicans. The resulting method is robust and highly reproducible, as demonstrated by the characterization of AgNPs from different rounds of syntheses and their antimicrobial activity.

Green and Simple Synthesis of Silver Nanoparticles by Aqueous Extract of Perovskia abrotanoides: Characterization, Optimization and Antimicrobial Activity

2020 ◽  
Vol 21 (11) ◽  
pp. 1129-1137 ◽  
Author(s):  
Somayeh Mirsadeghi ◽  
Masoumeh F. Koudehi ◽  
Hamid R. Rajabi ◽  
Seied M. Pourmortazavi
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Minimum Inhibitory Concentration ◽  
Plant Extract ◽  
Inhibitory Concentration ◽  
Minimum Bactericidal Concentration ◽  
Extraction Temperature ◽  
Silver Particles ◽  
Silver Nps ◽  
Perovskia Abrotanoides

Background: Herein, we report the biosynthesis procedure to prepare silver nanoparticles as reduction and capping agents with the aqueous plant extract of Perovskia abrotanoides. Methods: The therapeutic application of silver nanoparticles entirely depends on the size and shape of the nanoparticles therefore, their control during the synthesis procedure is so important. The effects of synthesis factors, for example, silver ion concentration, the mass of plant extract, reaction time and extraction temperature, on the size of silver particles were considered and optimized. Several analytical methods were used for the characterization of silver NPs including FT-IR and UV–Vis spectrophotometer, XRD and SEM. Results: The results showed that the mean size of the silver particles was about 51 nm. Moreover, the antibacterial properties of biosynthesized silver NPs were investigated by the minimum inhibitory concentration, minimum bactericidal concentration, and Well-diffusion tests. The minimum inhibitory concentration/ minimum bactericidal concentration values of silver NPs and aqueous plant extract versus Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and Gram-negative bacteria (E. coli) were 3.03/0.00, 1.20/0.01, 3.06/0.00, 0.98/1.04, 1.00/0.05 and 1.30/0.03 (mg/mL), respectively. Conclusion: The antimicrobial activity study displayed that the synthesized silver nanoparticles by plant extract have better antimicrobial properties compared to aqueous plant extract of Perovskia abrotanoides.

scholarly journals The influence of active carbon contaminants on the ozonation mechanism interpretation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lilla Fijołek ◽  
Joanna Świetlik ◽  
Marcin Frankowski
Keyword(s):  
Activated Carbon ◽  
Active Carbon ◽  
Alkali Metals ◽  
Activated Carbons ◽  
Carbon Surface ◽  
Bulk Solution ◽  
Ozone Decomposition ◽  
Reaction Products ◽  
Treatment Technology ◽  
Carbon Impurities

AbstractIn water treatment technology, activated carbons are used primarily as sorbents to remove organic impurities, mainly natural organic matter, but also as catalysts in the ozonation process. Commercially available activated carbons are usually contaminated with mineral substances, classified into two main groups: alkali metals (Ca, Na, K, Li, Mg) and multivalent metals (Al, Fe, Ti, Si). The presence of impurities on the carbon surface significantly affects the pHpzc values determined for raw and ozonated carbon as well as their acidity and alkalinity. The scale of the observed changes strongly depends on the pH of the ozonated system, which is related to the diffusion of impurities from the carbon to the solution. In an acidic environment (pH 2.5 in this work), the ozone molecule is relatively stable, yet active carbon causes its decomposition. This is the first report that indirectly indicates that contaminants on the surface of activated carbon (multivalent elements) contribute to the breakdown of ozone towards radicals, while the process of ozone decomposition by purified carbons does not follow the radical path in bulk solution. Carbon impurities also change the distribution of the reaction products formed by organic pollutants ozonation, which additionally confirms the radical process. The study showed that the use of unpurified activated carbon in the ozonation of succinic acid (SA) leads to the formation of a relatively large amount of oxalic acid (OA), which is a product of radical SA degradation. On the other hand, in solutions with purified carbon, the amount of OA generated is negligible.

scholarly journals Interrelations of Synthesis Method, Polyethylene Glycol Coating, Physico-Chemical Characteristics, and Antimicrobial Activity of Silver Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2475
Author(s):  
Amirah Shafilla Mohamad Kasim ◽  
Arbakariya Bin Ariff ◽  
Rosfarizan Mohamad ◽  
Fadzlie Wong Faizal Wong
Keyword(s):  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Polyethylene Glycol ◽  
Pathogenic Bacteria ◽  
Synthesis Method ◽  
Chemical Characteristics ◽  
Synthesis Methods ◽  
Uniform Size ◽  
Transmission Electron Microscopy Analysis ◽  
Physico Chemical

Silver nanoparticles (AgNPs) have been found to have extensive biomedical and biological applications. They can be synthesised using chemical and biological methods, and coated by polymer to enhance their stability. Hence, the changes in the physico-chemical characteristics of AgNPs must be scrutinised due to their importance for biological activity. The UV-Visible absorption spectra of polyethylene glycol (PEG) -coated AgNPs displayed a distinctive narrow peak compared to uncoated AgNPs. In addition, High-Resolution Transmission Electron Microscopy analysis revealed that the shapes of all AgNPs, were predominantly spherical, triangular, and rod-shaped. Fourier-Transform Infrared Spectroscopy analysis further confirmed the role of PEG molecules in the reduction and stabilisation of the AgNPs. Moreover, dynamic light scattering analysis also revealed that the polydispersity index values of PEG-coated AgNPs were lower than the uncoated AgNPs, implying a more uniform size distribution. Furthermore, the uncoated and PEG-coated biologically synthesised AgNPs demonstrated antagonisms activities towards tested pathogenic bacteria, whereas no antagonism activity was detected for the chemically synthesised AgNPs. Overall, generalisation on the interrelations of synthesis methods, PEG coating, characteristics, and antimicrobial activity of AgNPs were established in this study.

scholarly journals Green Synthesized Silver Nanoparticles Immobilized on Activated Carbon Nanoparticles: Antibacterial Activity Enhancement Study and Its Application on Textiles Fabrics

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3790
Author(s):  
Pratama Jujur Wibawa ◽  
Muhammad Nur ◽  
Mukhammad Asy’ari ◽  
Wijanarka Wijanarka ◽  
Heru Susanto ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Activated Carbon ◽  
Aloe Vera ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
E Coli ◽  
Transmission Electron ◽  
Average Size ◽  
Green Synthesized Silver Nanoparticles

This research aimed to enhance the antibacterial activity of silver nanoparticles (AgNPs) synthesized from silver nitrate (AgNO3) using aloe vera extract. It was performed by means of incorporating AgNPs on an activated carbon nanoparticle (ACNPs) under ultrasonic agitation (40 kHz, 2 × 50 watt) for 30 min in an aqueous colloidal medium. The successful AgNPs synthesis was clarified with both Ultraviolet-Visible (UV-Vis) and Fourier Transform Infrared (FTIR) spectrophotometers. The successful AgNPs–ACNPs incorporation and its particle size analysis was performed using Transmission Electron Microscope (TEM). The brown color suspension generation and UV-Vis’s spectra maximum wavelength at around 480 nm confirmed the existence of AgNPs. The particle sizes of the produced AgNPs were about 5 to 10 nm in the majority number, which collectively surrounded the aloe vera extract secondary metabolites formed core-shell like nanostructure of 8.20 ± 2.05 nm in average size, while ACNPs themselves were about 20.10 ± 1.52 nm in average size formed particles cluster, and 48.00 ± 8.37 nm in average size as stacking of other particles. The antibacterial activity of the synthesized AgNPs and AgNPs-immobilized ACNPs was 57.58% and 63.64%, respectively (for E. coli); 61.25%, and 93.49%, respectively (for S. aureus). In addition, when the AgNPs-immobilized ACNPs material was coated on the cotton and polyester fabrics, the antibacterial activity of the materials changed, becoming 19.23% (cotton; E. coli), 31.73% (polyester; E. coli), 13.36% (cotton; S. aureus), 21.15% (polyester; S. aureus).

In situ and facile synthesis of silver nanoparticles on baby wipes and their applications in catalysis and SERS

RSC Advances ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 5016-5023 ◽  
Author(s):  
Bharat Baruah
Keyword(s):  
Silver Nanoparticles ◽  
Composite Materials ◽  
Heterogeneous Catalyst ◽  
Facile Synthesis ◽  
Sers Substrates ◽  
Efficient Heterogeneous Catalyst

Silver nanoparticles were immobilized on fibers to create composite materials. The composites are shown to be efficient heterogeneous catalyst with very good recyclability. These composite materials are also proven to be good SERS substrates.

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