Size, stability, and aggregation of citrates-coated silver nanoparticles: contribution of background electrolytes

Author(s):  
F. Y. Alzoubi ◽  
Jehad.Y. Al-zou’by ◽  
Sirin. K. Theban ◽  
M. K. Alqadi ◽  
H. M. Al-khateeb ◽  
...  
2017 ◽  
Vol 9 (4) ◽  
pp. 431-447 ◽  
Author(s):  
F. Begum ◽  
S. A. Jahan ◽  
M. Y. A. Mollah ◽  
M. M. Rahman ◽  
M. A. B. H. Susan

Water in oil (W/O) microemulsions are simple preparative route for nanoparticles where water droplets dispersed in oil stabilized by surfactant or surfactant and cosurfactant monolayer act as nanoreactors to carry out chemical reactions. In this work, silver nanoparticles (AgNPs) were prepared in W/O microemulsions of cetyltrimethylammonium bromide (CTAB) and triton X-100 (TX-100) by using AgNO3 and NaBH4 as a precursor salt and reducing agent, respectively. To prepare microemulsions, CTAB or TX-100, 1-pentanol, cyclohexane and water were mixed with different molar ratio. AgNPs were prepared with different [AgNO3] in microemulsions of CTAB with fixed water to surfactant ratio (Wo). Average particle sizes were determined from dynamic light scattering (DLS) measurements. AgNPs prepared from microemulsions of CTAB were unstable while from TX-100, NPs were stable. Aggregation kinetics was investigated by measuring the absorbance at definite time intervals at the absorption maximum, ?max of AgNPs in different media under pseudo-first-order conditions. The aggregation behavior was studied at different [AgNO3]:[NaBH4] and Wo and the parameters were optimized to ensure formation of stable AgNPs without aggregation in microemulsions. This would help tuning the size, stability, and aggregation kinetics of AgNPs by controlling the nature of the surfactant and composition of the microemulsions.


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Chanyapat Ittibenjapong ◽  
Prit Kanjanahitanon ◽  
Punnita Chaichamni ◽  
Sirirat Panich ◽  
Nuchutha Thamsumet

Abstract Silver nanoparticles (AgNPs) have been widely used in many fields (e.g., sensors, medical supplies, food, cosmetics, medicines, etc.) due to their unique properties such as optical property, antibacterial property, and high conductivity. AgNPs are normally synthesized by chemical, physical, or biological methods. Among these methods, biological synthesis or green synthesis of AgNPs has drawn much attention since it is an easy and environmental-friendly method. Herein, AgNPs synthesized using Catunaregam tomentosa extracts were studied. The extracts obtained from different C. tomentosa fruit were found to be blue, green, and brown. It was found from the foam test and IR spectra that all extracts (blue, green, and brown extracts) contained saponins. According to the DPPH assay, the blue and the green extracts had the antioxidant activities of 84.47 ± 12.13 and 47.66 ± 2.86 mg ascorbic acid equivalent/g of C. tomentosa powder, respectively. This showed that the blue and the green extracts could act as reducing agents in AgNPs synthesis. The successfully synthesized AgNPs using C. tomentosa extracts showed the surface plasmon resonance peak at 400 nm corresponding to literatures. The particle sizes and zeta potential values measured by dynamic light scattering also indicated the size stability of the synthesized AgNPs during seven-day period with no significant difference (P > 0.05).


2019 ◽  
Vol 107 (3) ◽  
pp. 305
Author(s):  
Mengmei Geng ◽  
Yuting Long ◽  
Tongqing Liu ◽  
Zijuan Du ◽  
Hong Li ◽  
...  

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.


TAPPI Journal ◽  
2016 ◽  
Vol 15 (8) ◽  
pp. 515-521 ◽  
Author(s):  
EIJA KENTTÄ ◽  
HANNA KOSKELA ◽  
SARA PAUNONEN ◽  
KARITA KINNUNEN-RAUDASKOSKI ◽  
TUOMO HJELT

This paper reports experiments on silica coating formulations that are suitable for application as a thin pigment layer with foam coating technique on a paper web. To understand the foaming properties of nanosilica dispersions, the critical micelle concentration, foam half-life time, and foam bubble size stability were determined with three different foaming agents. The results indicate that the bubble stability measurement is a useful characterization method for foam coating purposes. Pilot foam coating trials were done and the effects of the chosen foaming agents were studied on the properties of the nanosilica-coated paper. The surface hydrophilicity of silica coated paper was related not only to silica pigment, but also to the chemical nature of the foaming agent. Standard paper properties were not affected by the thin silica coating.


Author(s):  
S. Rezaei-Zarchi ◽  
M. Taghavi-Foumani ◽  
S. Razavi Sheshdeh ◽  
M. Negahdary ◽  
G. Rahimi

2019 ◽  
Vol 29 (3) ◽  
Author(s):  
Mai Ngọc Tuan Anh

Silver nanoplates (SNPs) having different size were synthesized by a seed-mediated method. The seeds -silver nanoparticles with 4 – 6 nm diameters were synthesized first by reducing silver nitrate with sodium borohydride in the present of Trisodium Citrate and Hydrogen peroxide. Then these seeds were developed by continue reducing Ag\(^+\) ions with various amount of L-Ascorbic acid to form SNPs. Our analysis showed that the concentratrion of L-Ascorbic acid, a secondary reducing agent, played an important role to form SNPs. In addition, the size and in-plane dipole plasmon resonance wavelenght of silver nanoplates were increased when the concentration of added silver nitrate increased. The characterization of SNPs were studied by UV-Vis, FE-SEM, EDS and TEM methods.


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