scholarly journals Synthesis of silver nanoparticles using supercritical water

2018 ◽  
pp. 22-25
Author(s):  
Buyankhishig B ◽  
Narandalai B ◽  
Enkhtuul S
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Electron Microscope ◽  
Reaction Time ◽  
Supercritical Water ◽  
Silver Salt ◽  
Activated Carbons ◽  
Batch Reactor ◽  
Acetate Solution ◽  
Silver Acetate

Supercritical water (SCW) technology is a relatively novel and green method compared with others for the synthesize of metal nanoparticles. It is considered one of the most suitable methods for loading nanoparticles in surface of porous materials due to the water in supercritical conditions has a high diffusivity, well dispersive and it has a same carrier characteristic as like a gas. Silver nanoparticles and silver loaded activated carbons were synthesized using silver acetate solution under supercritical water condition at 4000C and 31.15 MPa in a batch reactor. This study was investigated effect of operational parameters on the particle size of silver nanoparticles in particularly the concen-tration of silver salt solution and the reaction time. The experiments were carried out to test the silver salt concentra-tion at 0.01 M, 0.02 M, 0.05M, and the reaction time of 15 and 30 minutes. When the silver acetate concentration and reaction time increased agglomerations of silver particles were observed on the surface of activated carbons. The structure, morphology and particle size of synthesized products were determined by X-ray diffraction (XRD), Scan-ning electron microscope (SEM) and Transmission electron microscope (TEM). Суперкртитик усан орчинд мөнгөний нанопартиклыг гарган авах Хураангуй: Суперкритик усны арга нь металлын нанопартикл гарган авах бусад аргуудтай харьцуулахад харьцангуй шинэ арга юм. Суперкритик нөхцөл дахь ус нь диффузийн коэффициент өндөртэй, тархалт сайтай, хийтэй адил зөөж тээвэрлэх шинж чанар үзүүлдэг тул сүвэрхэг материал дээр нанопартикл үүсгэхэд тохиромжтой аргуудын нэг гэж үздэг. Мөнгөний нанопартикл болон идэвхжүүлсэн нүүрсэн дээр суулгасан мөнгөний нанопартиклыг суперкритик усны аргаар мөнгөний давсны усан уусмал хэрэглэн гарган авсан. Мөнгөний нанопартиклыг гарган авахад нөлөөлөх гол хүчин зүйлүүдэд хамаарах мөнгөний давсны уусмалын концентрац болон урвал явагдах хугацааны нөлөөг судалсан бөгөөд концентрацыг 0.01 М, 0.02 М ба 0.05 М, харин урвал явагдах хугацааг 15 ба 30 минут гэсэн нөхцөлүүдэд туршилтыг явуулсан. Урвал явагдах хугацаа болон мөнгөний давсны уусмалын концентрац ихсэхэд үүссэн мөнгөний жижиг хэсгүүдийн бөөгнөрөл илүү нэмэгдэж байсан. Гарган авсан материалуудын талст бүтэц, түүний хэмжээ болон морфологийн шинж чанарыг рентген дифрактометр (XRD), сканнинг электрон микроскоп (SEM) болон нэвтрүүлэлтийн электрон микроскоп (TEM) ашиглан тодорхойлсон. Түлхүүр үг: Суперкритик ус, мөнгөний нанопартикл, урвал явагдах хугацаа, уусмалын концентрац.

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.

Characterization of Silver Loaded Activated Carbon Prepared under Supercritical Water Condition

2019 ◽  
Vol 288 ◽  
pp. 59-64
Author(s):  
Narandalai Byamba-Ochir ◽  
Battseveen Buyankhishig ◽  
Nyamsuren Byambasuren ◽  
Enkhtuul Surenjav
Keyword(s):  
Electron Microscopy ◽  
Activated Carbon ◽  
Supercritical Water ◽  
Fine Particles ◽  
Batch Reactor ◽  
Reaction Times ◽  
Acetate Solution ◽  
Reaction Rate Increase ◽  
Water Condition ◽  
Low Dielectric

The synthesis of silver nanoparticles loaded on the activated carbon (AC) surface were performed under SCW condition at 673 K and 31.15 MPa in a batch reactor. In supercritical region, fine particles are rapidly synthesized due to reaction rate increase at low dielectric constant of supercritical water. Samples were prepared with different concentrations of silver acetate solution and various reaction times. The synthesized silver loaded on AC particles were characterized by the Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). FTIR spectrum of primary activated carbon, activated carbon treated under supercritical water condition and synthesized AC-Ag was compared. The particles size and crystallite size of silver deposited on AC surface were analyzed by TEM and XRD, respectively.

Co-Pyrolysis of Polyethylene Plastic and Cellulose as Models for Medical Waste in Supercritical Water

2014 ◽  
Vol 1010-1012 ◽  
pp. 952-955 ◽  
Author(s):  
Yan Meng Gong ◽  
Shu Zhong Wang ◽  
Xing Ying Tang
Keyword(s):  
Organic Matter ◽  
Reaction Time ◽  
Supercritical Water ◽  
Time Pressure ◽  
Batch Reactor ◽  
Medical Waste ◽  
Oil Yield ◽  
Mass Ratio ◽  
Gaseous Products ◽  
Gasification Efficiency

Co-pyrolysis of polyethylene plastic and cellulose as models for medical waste had been studied on a supercritical water batch reactor. The results show that temperature, reaction time, pressure and the mass ratio of water to organic matter have some degree impact on the conversion rate, oil yield and gasification efficiency. Conversion and gasification efficiency reached the maximum values at 440 °C. The content of H2 in the gaseous products rose significantly between 25 MPa~27 MPa. As reaction time increased, conversion and gasification efficiency increased, but oil yield decreased. The composition of gaseous products was affected greatly by the mass ratio of water to organic matter. Adding K2CO3 and Ca (OH)2 as catalyst, the reaction was promoted obviously.

scholarly journals Characterization, Antimicrobial and Antioxidant evaluation of biofabricated silver nanoparticles from endophytic Pantoea anthophila

2021 ◽  
Author(s):  
C. Nirmala ◽  
M Srid
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Electron Microscope ◽  
Pathogenic Bacteria ◽  
Average Particle Size ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Average Particle ◽  
X Ray ◽  
Uv Visible

Abstract Endophyte mediated nanoparticles fabrication was emerging as a new frontier in nanomedicines that produce high biocompatible and functionalized silver nanoparticles. In this study, silver nanoparticles were successfully biosynthesized from the extracellular extract of endophytic bacterium Pantoea anthophila isolated from the stem of Waltheria indica for the first time. The synthesised nanoparticles were characterized by UV-Visible and Fourier Transform Infra-Red spectroscopy. The structural analysis is done by X-ray diffraction and the stability was studied by dynamic light scattering and particle size analyser. The size and shape were observed by Transmission Electron Microscope, Scanning Electron Microscope and Energy Dispersive X-Ray spectrum. Further, the nanoparticles were evaluated for antimicrobial and antioxidant properties. Synthesized nanoparticle showed a strong absorption band in the UV-Visible range at 410 nm. The average particle size was found to be 16.8 nm with spherical shaped, crystalline nature. Good zones of inhibition at various ranges were detected against a broad range of human pathogenic bacteria and fungi. A strong free radical scavenging activity of silver nanoparticles with IC50 values 30.75, 19.47, 34.59, 41.12, 27.24, 28.16, 36.21 µg/ml was obtained that was comparable to the reference. The study suggests that the silver nanoparticles can be biosynthesised from endophytic P. anthophila metabolites with significant therapeutic potential. With proper validation, the biosynthesised silver nanoparticles can be developed as a promising antiviral and anticancer drug candidate.

Green Synthesis of Silver Nanoparticles Using Elaeis guineensis (Palm Leaves): An Investigation on the Effect of Reaction Time in Reduction Mechanism and Particle Size

2014 ◽  
Vol 575 ◽  
pp. 36-40 ◽  
Author(s):  
Nor Ain Ramli ◽  
Junaidah Jai ◽  
Noorsuhana Mohd Yusof
Keyword(s):  
Particle Size ◽  
Silver Nanoparticles ◽  
Reaction Time ◽  
Green Synthesis ◽  
Elaeis Guineensis ◽  
Silver Ions ◽  
Reduction Reaction ◽  
Reduction Mechanism ◽  
Transmission Electron ◽  
Scanning Electron Microcopy

In this research, green synthesis of silver nanoparticles using elaeis guineensis leaves extract was investigated and the effect of reaction time in reduction mechanism and particle size is studied. UV-visible sprectrophotometer was used to monitored the reduction reaction of silver ions to silver nanoparticles and formation of silver nanoparticles shown at 15 minutes. Transmission electron microscopy (TEM) and field emission scanning electron microcopy (FESEM) shows polydispersed and irregular shape of silver nanoparticles with aggregation. Further confirms the formation of silver nanoparticles by energy dispersive x-ray analysis (EDAX). From this research, it was found that the increasing reaction time increases the rate of reduction reaction of silver ions.

Synthesis, performance and growth mechanism of silver nanoparticle coated SERS fiber probe

2019 ◽  
Vol 107 (3) ◽  
pp. 305
Author(s):  
Mengmei Geng ◽  
Yuting Long ◽  
Tongqing Liu ◽  
Zijuan Du ◽  
Hong Li ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Reaction Time ◽  
Growth Mechanism ◽  
Fiber Optic ◽  
Fiber Optic Probe ◽  
Visible Absorption ◽  
Fiber Probe ◽  
Surface Enhanced Raman ◽  
Optic Probe

Surface-enhanced Raman Scattering (SERS) fiber probe provides abundant interaction area between light and materials, permits detection within limited space and is especially useful for remote or in situ detection. A silver decorated SERS fiber optic probe was prepared by hydrothermal method. This method manages to accomplish the growth of silver nanoparticles and its adherence on fiber optic tip within one step, simplifying the synthetic procedure. The effects of reaction time on phase composition, surface plasmon resonance property and morphology were investigated by X-ray diffraction analysis (XRD), ultraviolet-visible absorption spectrum (UV-VIS absorption spectrum) and scanning electron microscope (SEM). The results showed that when reaction time is prolonged from 4–8 hours at 180 °C, crystals size and size distribution of silver nanoparticles increase. Furthermore, the morphology, crystal size and distribution density of silver nanoparticles evolve along with reaction time. A growth mechanism based on two factors, equilibrium between nucleation and growth, and the existence of PVP, is hypothesized. The SERS fiber probe can detect rhodamin 6G (R6G) at the concentration of 10−6 M. This SERS fiber probe exhibits promising potential in organic dye and pesticide residue detection.

Synthesis and Characterization of Florfenicol-silver Nanocomposite and its Antibacterial Activity against some Gram Positive and Gram-negative Bacteria

2020 ◽  
Keyword(s):  
Silver Nanoparticles ◽  
Electron Microscope ◽  
Zeta Potential ◽  
Surface Area ◽  
Spherical Shape ◽  
Bet Surface Area ◽  
Sonochemical Method ◽  
Raman Spectrometry ◽  
Silver Nanocomposite ◽  
Morphology Characterization

In this paper, easy, rapid and cheap synthetic method was described for florfenicol-silver nanocomposite by sonochemical method. Florfenicol-silver nanocomposite was characterized based on three classes namely index, identification and morphology class. Index characterization was carried out by zeta sizing, BET surface area and zeta potential. Identification characterization was performed using X-ray diffraction (XRD) and Raman spectrometry. Morphology characterization was done utilizing transmission electron microscope (TEM), scanning electron microscope (SEM) and atomic force microscope (AFM). Characterization results showed zeta sizing of florfenicol was 30.44nm, while florfenicol-silver nanocomposite was 33.5 nm with zeta potential -14.1 and -18, respectively. BET surface area was found to be 13.3, 73.2 and 103.69 m2/g for florfenicol, silver nanoparticles and florfenicol-silver nanocomposite respectively. XRD and Raman charts confirmed the formation of florfenicol-silver nanocomposite without any contamination. TEM, SEM and AFM spectral data illustrated spherical to sub spherical shape of silver nanoparticles on cubic to sheet shape of florfenicol with size less than 50 nm. Antimicrobial activity was screened where the average zone of inhibitions caused by the prepared nanocomposite were 28.3 mm, 24 mm, 27.3 mm and 24 mm compared to 17.7 mm, 16 mm, 18.7 mm and 13.3 mm of the native drug and 13 mm, 10 mm, 14.3 mm and 15 mm of the used positive reference standards against E. coli, Salmonella typhymurium, Staphylococcus aureus and Staph.aureus MRSA respectively.

scholarly journals Feasibility of fly ash as fluxing agent in mid- and low-grade phosphate rock carbothermal reduction and its reaction kinetics

2021 ◽  
Vol 10 (1) ◽  
pp. 157-168
Author(s):  
Biwei Luo ◽  
Pengfei Li ◽  
Yan Li ◽  
Jun Ji ◽  
Dongsheng He ◽  
...  
Keyword(s):  
Particle Size ◽  
Fly Ash ◽  
Reaction Time ◽  
Carbothermal Reduction ◽  
Industrial Waste ◽  
Phosphate Rock ◽  
Molar Ratio ◽  
Low Grade ◽  
Carbon Excess ◽  
Fluxing Agent

Abstract The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

Shape and stability of silver nanoparticles and their dependence on the conditions of preparation.

2012 ◽  
Vol 1371 ◽  
Author(s):  
M.I. Hernández-Castillo ◽  
O. Zaca-Moran ◽  
P. Zaca-Moran ◽  
M. Rojas-López ◽  
V.L. Gayou ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Reaction Time ◽  
Ag Nanoparticles ◽  
Reduction Procedure ◽  
Visible Spectrophotometry ◽  
Logical Sequence ◽  
Uv Visible ◽  
Citrate Reduction ◽  
Shape And Size

ABSTRACTBy using the citrate reduction procedure we have synthesized Ag nanoparticles, applying several conditions of preparation, being after characterized by UV-visible spectrophotometry. Following a logical sequence, the starting experiment was realized varying the reaction time, after that it was varied the concentration of the reductor agent, and finally it was varied the volume of the reductor agent. According to this methodology, TEM measurements show that firstly we have nanostructures with different shape and size, whereas in the last part of the experiment we have Ag nanoparticles with homogeneous shape and size.

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