Preparation of silver nanoparticles with controlled particle size (original) (raw)
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Analysis of Silver Nanoparticles Produced by Chemical Reduction of Silver Salt Solution
In the present research silver colloid was produced by chemical reduction of silver salt (silver nitrate AgNO3) solution. As a reducer sodium citrate was used. UV-VIS spectrometry indicated formation of nanoparticles. The surface plasmon resonance peak in absorption spectra of silver colloidal solution showed an absorption maximum at 450 nm. Comparison of theoretical (Mie light scattering theory) and experimental results showed that diameter of silver nanoparticles in colloidal solution is about 100 nm. Silver nanoparticles were deposited on two substrates: silica (SiO2) and polyethylene terephthalate (PET) modified with various polymers (polycarbonate (PC), polymethyl methacrylate (PMMA), polystyrene (PS)). The colloidal silver was incorporated by dip-coating to the polymer-substrate structures. X-ray fluorescence spectroscopy (XRFS) and atomic force microscopy (AFM) results indicate that produced structures include silver nanoparticles. It was found that during deposition, silver ...
Preparation and characterization of silver nanoparticles by chemical reduction method
Colloids and Surfaces B-biointerfaces, 2011
Silver nanoparticles were prepared by the reduction of AgNO 3 with aniline in dilute aqueous solutions containing cetyltrimethlyammonium bromide, CTAB. Nanoparticles growth was assessed by UV-vis spectroscopy and the average particle size and the size distribution were determined from transmission electron microscopy, TEM. As the reaction proceeds, a typical plasmon absorption band at 390-450 nm appears for the silver nanoparticles and the intensities increase with the time. Effects of [aniline], [CTAB] and [Ag + ] on the particle formation rate were analyzed. The apparent rate constants for the formation of silver nanoparticles first increased until it reached a maximum then decreased with [aniline]. TEM photographs indicate that the silver sol consist of well dispersed agglomerates of spherical shape nanoparticles with particle size range from 10 to 30 nm. Aniline concentrations have no significant effect on the shape, size and the size distribution of Ag-nanoparticles. Aniline acts as a reducing as well as adsorbing agent in the preparation of roughly spherical, agglomerated and face-centered-cubic silver nanoparticles.
Influence of Reagents on the Synthesis Process and Shape of Silver Nanoparticles
Materials
The aim of this study was to prepare the silver nanoparticles (AgNPs) via chemical reduction and analyze the impact of used reduction agents: sodium borohydride (NaBH4), trisodium citrate (TSC), polyvinylpyrrolidone (PVP), and hydrogen peroxide (H2O2) on the reduction rate of Ag+ ions to Ag0, and on nanoparticles shape. It was proven that combinations of reduction agents dramatically influence the synthesis rate of AgNPs and the color of solutions, which depends on the shape and size of nanoparticles. NaBH4, TSC, and PVP showed good reduction power. In particular, TSC proved to be a key factor influencing the shape of AgNPs. The shape of nanoparticles influences the color of colloidal solutions. Yellow solutions, where UV-vis absorbance maxima (ABSmax) are in the wavelength interval 380–420 nm, contain spherical particles with a mean size of 25 nm, whereas the blue shift of ABSmax to wavelengths higher than 750 nm indicate the presence of triangular nanoparticles (size interval 18–1...
Synthesis and characterization of silver nanoparticles by chemical reduction method
Colloids and Surfaces B-biointerfaces, 2011
Nanoparticles, compared to micro particles have distinctly different properties and advanced characteristics. Silver nanoparticles are one of the metal nanoparticles which has varied and different properties when compared to other material. Silver nanoparticles have received considerable attention due to their attractive physical and chemical properties, Especially suitable for sensor applications, while there are different methods for synthesis of silver nanoparticles, the most popular preparation of Ag nanoparticles is by chemical reduction. Silver nitrate is taken as the metal precursor and sodium borohydride as a reducing agent. This preparation is simple, but the great care must be exercised to make stable particles. Here silver nanoparticles are synthesized by the chemical reduction of silver nitrate. These silver nanoparticles are characterized by the different techniques like UV-Vis spectroscopy for the structural characterization, SEM to know the size morphology and composition of nanoparticles, XRD to know the lattice parameters. The UV-Vis spectroscopy revealed the formation of silver nanoparticles by exhibiting the typical surface Plasmon absorption maxima at a wavelength of 420nm as observed. From the UV Vis spectrum the agglomerated grain diameter size is estimated around 60 nm. The peaks in the XRD pattern are in good agreement with the standard values of the face-centered-cubic form of metallic silver (ICCD-JCPDS card no.04-0783) and no peaks of other impurity crystalline phrases are detected. The energy dispersive spectroscopy (EDS) of the nanoparticles dispersion confirms the presence of elemental silver in nanoscale.
Preparation of colloidal silver nanoparticles and structural characterization
2013
In this paper, we prepare silver nanoparticles colloids by using polyvinyl pyrrolidone (PVP) of four different molecular weights (MW = 10000, 29000, 40000, 55000) as a protective agent, dextrose as reduction agent and by adding urea which produce intermediates AgOCN and Ag2CO3. Results indicated that PVP effects against agglomeration would depend to a great extent on the hydroxide and urea concentrations used in the reaction medium. When NaOH was dominant, the reaction rate was very fast and hence only PVP with large molecular weight produced small silver colloids of sizes around 20 nm. On the other hand, when urea was dominant, the reaction path was significantly changed and slowed down as well; under this circumstance, PVP with MW of 10000 offered the best protection against agglomeration, it produced silver colloids of only 26 nm. A part of our silver nanoparticles was extracted as powder, to be characterized by XRD, and another part was deposited on glass substrates, by spin-coa...
Formation and stability study of silver nano-particles in aqueous and organic medium
−Colloidal silver nanoparticles were obtained by chemical reduction of silver nitrate in water and organic solvent with sodium borohydride. The effects of oxidant, reducing agent, stabilizer, and temperature, during the growth of silver nanoparticles were discussed. As the reaction proceeded in aqueous medium a characteristic plasmon absorption peak between 390-420 nm appeared as presence of silver nanoparticles. The peak intensities and shifting (blue or red) were altered in accordance with some applied factors. The formed silver nanoparticles were found to be with particles size range from 3 to 20 nm. The change rates of Ag + ions to Ag 0 in aqueous and organic solvent are strongly temperature dependent, although reduction can take place at room temperature. The silver nano-colloid with negative zeta potential also has been confirmed to be more stable. Obtained nanoparticles were characterized by UV-vis spectropho-tometer, particle analyzer for zeta (ζ) potential, polydispersity index (PDI), and transmission electron microscope (TEM).
A simple method for the preparation of colloidal polymer-supported silver nanoparticles
Journal of Nanoparticle …, 2011
Polysulfone-silver composite nanoparticles have been prepared by combining polymer nanoprecipitation and redox synthesis of silver, in the presence of a glucose-modified cyclosiloxane as stabilizing agent. Based on previous kinetic investigations and on model reactions, we concluded that the reducing agent in this case is the tetrahydrofuran (THF) used as solvent for polysulfone. Dynamic light scattering measurements on the obtained polymersilver composite particles indicated particle average diameter of 176 nm with a polydispersity index of 0.25. The UV-vis spectrum exhibited the silver plasmon resonance. By different microscopic methods (atomic force microscopy-AFM, high resolution transmission electron microscopy-HRTEM, and scanning electron microscopy-SEM), larger polymer particles coated with silver nanoprticles were observed. The Energy Dispersive X-Ray analysis-EDX; confirmed the presence of Ag on the surface of the particles, while the selected area electron diffraction showed single crystalline silver nanospheres with face-centered cubic structure.
Synthesis and characterization of silver nanoparticles
2007
Silver nanoparticles have received considerable attention due to their attractive physical and chemical properties. The surface plasmon resonance and large effective scattering cross section of individual silver nanoparticles make them ideal candidates for molecular labeling, where phenomena such as surface enhance Raman scattering (SERS) can be exploited. In addition, silver nanoparticles have recently been shown to be a promising antimicrobial material. In the present research silver colloid was produced by sodium citrate reduction. The colloidal silver was incorporated by dip-coating to the polymer substrate. X-Ray Fluorescence Spectroscopy (XRF), Atomic force microscopy (AFM), ultraviolet-visible spectroscopy (UV-VIS ) and SERS indicate that the produced structures include metallic crystalline silver nanoparticles. The surface plasmon resonance peak in absorption spectra of silver particles showed an absorption maximum at 420-500 nm. The silver - polymer nanocomposites structures with selective light properties as a result of plasmon resonance shifting in the UV-VIS wavelength region were produced.
Research on Chemical Intermediates, 2010
Importanţa nanoparticulelor metalice este dată de performanţele lor magnetice, electronice şi optice. Ca urmare a proprietăţilor specifice, ele au multe aplicaţii ca biosenzori şi catalizatori în biomedicină şi in domeniului mediului. Scopul acestei lucrări este prezentarea metodei de obţinere şi analiză a filmelor polimerice pe bază de Ag/alcool polivinilic/acid tanic. Nanoparticulele de Ag au fost preparate prin reducerea AgNO 3 utilizând diferiţi agenţi de reducere (alcool polivinilic sau acid tanic) prin sinteză în câmp de microunde. Nanoparticulele de Ag (soluţii şi film) au fost caracterizate prin spectroscopie UV -VIS , FTIR şi DLS (Dinamic Light Scattering).
Green synthesis of silver nanoparticles and silver colloidal solutions
Journal of Physics: Conference Series, 2009
In this paper, silver colloidal solutions have been synthesized rapidly in green conditions by using microwave irradiation and non-toxic chemistry substances (acid oxalic, silver nitrate, polyvinyl pyrolidone (PVP; Mw = 55 000)). The particle size and morphology of these solutions can be controlled by altering several factors like the time, the power of microwave exposure, and the ratio of silver oxalate and PVP etc. The silver nanoparticles were fabricated by thermal decomposition of silver oxalate. The synthesized silver colloidal solutions and silver nanoparticles were characterized by several analytical techniques like UV-VIS, XRD, TEM, FESEM/EDS and ICP-AAS studies. Finally, we used the synthesized silver colloidal solutions for antibacterial purpose. The obtained results showed that the synthesized silver colloidal solutions, even at very low concentrations, have highly efficient anti-bacterial property.