• Korean Journal of Materials Research
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• v.19 no.11
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• pp.569-575
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• 2009

In this study, the effects of silver treatment and activation on the physical and chemical properties of spherical activated carbon (SAC) were studied. The textural properties of SAC were characterized by BET surface area, XRD, SEM, iodine adsorption, strength intensity, pressure drop and antibacterial effects. BET surface areas of SACs decreased with an increase of the amount of PR before and after activation, and the BET surface areas of SACs were found to be about 2-3 times the size of those before activation. The XRD patterns showed their existing state as stable Ag crystals and carbon structure. The Ag particles are seaweedlike and uniform, being approximately 5-10 μm in size deposited on the surface of activated carbon. All of the samples had much more iodine adsorption capability after activation than before activation. The strength values of SACs increased with an increase of the amount of PR, and there was a smaller drop in the strength values of SACs with silver treatment than with non-silver treatment after activation. The Ag-SAC composites showed strong antibacterial activity against Escherichia coli (E. Coli).

• Resources Recycling
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• v.3 no.2
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• pp.17-23
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• 1994

The dissolution of gold and silver from concentrate was studied with acidic thiourea solution. The results showed that the gold and silver extraction was severely affected by concentration of thiourea and oxidant, pulp density, etc. Especially, oxidant such as ferric ions enhanced the leching rate of gold and silver. High concentration of ferric ions, however, dissolved the sulfide ore to form electrochemically passive layer on the surface of ore particles, which caused the precious metal not to be leached out from the ore. The use of $SO_2$could not effectively enhance the recovery of precious metal but reduce to some extent the consumption of thiourea. The leaching of gold and silver was achieved with recovery more than 90% and 80%, respectively, under the following conditions; Thiourea conc. :0.4M Oxidant : None $H_2SO_4$ conc. : 0.5M Pulp density : <10% Leaching time :4 Hrs Potential :250mV The Thiourea was consumed about 10% in comparison with its initial concentration.

• Fashion & Textile Research Journal
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• v.6 no.4
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• pp.503-510
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• 2004

The study is one of fundamental researches for the development of future smart clothing and textile products with blocking properties from electromagnetic waves by analyzing human physical symptoms in using electromagnetic products in such an environments. Among various textiles in the experiment, nano silver has shown the best blocking performance from electromagnetic waves, which decreases depending on the distance. The power spectrum distribution and the incidence of electroencephalogram between blocking materials and aural stimuli has shown that, ${\beta}$, wave appeared to be active in all channels except for $T_4$, whereas all waves appeared with processed materials and especially with nano silver silk(NSS), ${\alpha}$, ${\beta}$, ${\theta}$, ${\gamma}$ waves appeared active in all regions. As for the brain mapping of ${\alpha}$ wave according to time, there found a strong activity in $P_3$, $P_4$ of the parietal lobe, with all materials on all time regions. With silk nylon metal(SNM) and NSS, it appeared strong in $F_3$, $F_4$ as well. As for ${\beta}$, wave, the activity appeared strong in frontal lobe before 7min. 30sec, where it tends to diminish abruptly in 7min. 30sec. to 13min. 30sec. region. After 13min., it regained gradually. With NSS, it appeared strong in all areas except for the farthest $T_4$. The appearance of ${\nu}$ wave can be deduced as it can affect human body with its toxic property while the silver particles become nano-sized. Therefore, the study conducted with human participants requires a proper particle size of it which would not penetrate cellular tissues and a proper binder and binding treatment for it, to prevent the physical fatigues and the potential diseases. However, it is highly required for back-up researches to verify various aspects in applying nano silver to textile products.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.701-709
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• 1992

Silver particles were impregnated on carbon black with colloidal method and used as catalyst for oxygen electrode in alkaline fuel cell. With the addition of sodium dodecylbenzenesulfonate in $AgNO_3$ and $NaBH_4$solution, colloidal solution was made and confirmed with electrophoresis test. Effects of particle size on electrode performance were studied and $200{\AA}$ of silver particle size shown the highest value of mass activity. The aggromeration of silver particle was Influenced with surfactant amount, stirring time and heat treatment. Considering the increase of particle size caused of operating temperature, recommendable particle size of silver catalyst for manufacturing the electrode was $100{\AA}$. Dispersity of carbon black was investigated and reagglomeration was appeared after homogenizing 30 sec.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.364-371
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• 2007

Effects of continuous oil phase on silver halide nanoparticles were investigated where nanoparticles were prepared using two different types of water-in-oil(W/O) microemulsions containing silver and halide, respectively. Phase behavior experiments for ternary systems containing AOT surfactant, hydrocarbon oil and aqueous solution of an inorganic salt showed that the region of one phase W/O microemulsion was found to be broadened with an increase in the alkyl chain length of a hydrocarbon mainly due to an increase in hydrophilic nature of a surfactant. With the information of phase behavior experiments, silver halide nanoparticles were prepared using different AOT-based microemulsion systems and photomicrographs obtained by transmission electron microscopy indicated that about 10 nm size particles of relatively spherical shape were obtained. It has been found that an increase in alkyl chain length of a hydrocarbon results in a decrease in particle size because of higher intermicellar exchange rate among microemulsion drops. The average particle size was also found to increase with the inorganic salt composition of initial aqueous solution.

• Journal of Radiation Industry
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• v.5 no.2
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• pp.119-124
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• 2011

Silver nano-particles (AgNPs) have attracted much attention for centuries due to their unique optical properties, electrical conductivities, oxidative catalysis, and antibacterial effect. In this study, AgNPs have been prepared by using aqueous $AgNO_3$ solution in the poly(vinyl alcohol) (PVA)/poly(ethylene glycol) (PEG) hydrogels. PVA and PEG powders were dissolved in deionized water, and then irradiated by a gamma-ray with a radiation dose of 50 kGy to make hydrogels. PVA/PEG hydrogels were dipped into $1.0{\times}10^{-2}M$ $AgNO_3$ solution for 1 hour. After that, the swollen hydrogels were irradiated by gamma-ray for the formation of AgNPs. FE-SEM is used to observe the formation of AgNPs as a function of the content of PEG and the irradiation dose. Also, AgNPs in the PVA/PEG hydrogels were monitored by UV-Vis. It is observed that the content of PEG and gamma-ray irradiation in the hydrogel is crucial to the formation of AgNPs. Finally, antibacterial tests indiacted that the hydrogel containing silver nanoparticle has antibacterial activity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.4
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• pp.772-779
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• 2016

Silver nanoparticles were prepared by reacting silver nitrate and trisodium citrate in an aqueous solution. Their size and shape were investigated by scanning electron microscopy (SEM). The synthesis was carried with different silver nitrate concentration, addition of TSC, solvent, surfactant, ultrasonication, and dispersing agent. With higher concentration of silver nitrate or TSC, the particles became large or agglomerated. The SEM results showed that the nanoparticles have spherical and pseudospherical shape with a narrow size distribution. The hydrophobic solvent did not affect the dispersibility, but the hydrophilic solvent enhanced it. The addition of HPMC surfactant caused the size to increase (50-100 nm) with non-uniform shapes and partial agglomeration. The dispersibility was significantly improved by ultrasonication for over 3 hours after the addition of a dispersing agent. Complete dispersion was achieved by adding the dispersant, and the nanoparticle sizes were as follows: 30-40 nm (BYK-182) < 42-78 nm (BYK-192) < 51-113 nm (BYK-142). The nanoparticles were 38.45-46.28 nm after the addition of 2-4 wt% TSC in 0.002 M silver nitrate solution.

• Journal of the Korean Society of Visualization
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• v.15 no.2
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• pp.16-20
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• 2017

A coffee-ring effect is from capillary flow by different evaporation rate across the droplet. The capillary flow tends particles to accumulate at the edges of the droplet and makes the ring-shaped stain pattern. These coffee-ring formation and suppression of coffee-ring have been a critical role in printing and coating technologies. In this study, we present the experimental study on coffee-ring effect of silver nanowire inside the evaporating sessile droplet. Size and concentration effect of nanowires at coffee-ring effect has been investigated. From the coffee-ring, we observed the regimes of connected rings and disconnected ones and measure the resistivity of single ring pattern with different nanowire length.

• Journal of Powder Materials
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• v.12 no.6 s.53
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• pp.428-432
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• 2005

In the present study, silver-doped antibacterial hydroxyapatites were successfully prepared by the sol-gel method. For the starting solution, the molar ratio of $Ca(NO_3)_2{\cdot}4H_2O, P(OC_2H_5)_3,\;C_2H_5OH,\;and\;H_O$ was set to 0.075:0.045:20:0.135; $AgNO_3$ was added to a ratio of Ag to total cation concentration of $0.5-12 mol\%$. The prepared sol was dried at $100^{\circ}C$ for 48h and heat-treated at $1000^{\circ}C$ for 2h to obtain particles in the 200-500nm size range. The product from the synthesis of silver-doped hydroxyapatite was investigated through X-ray diffraction experiments and scanning electron microscopy. The product showed high antibacterial properties, with a disinfection ratio of Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 25922) over $99.9^{\circ}C$ as calculated from an antimicrobial effects evaluation by the shake flask method.

• Current Photovoltaic Research
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• v.2 no.2
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• pp.63-68
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• 2014

In recent years, discoloration defects, called as snail trail, have been observed at many crystalline photovoltaic modules after a period of time ranging from several months to several years after initial installation. It has been reported that this phenomenon doesn't impact on the performance of photovoltaic modules, but it can be detected through simple visual inspection. The origin and detailed mechanism for the formation have not been identified. In this study, non-destructive analysis by Raman spectroscopy has been carried out to investigate the origin of this phenomenon. In parallel, destructive analysis by scanning electron microscopt and transmission electron microscopy was also performed in order to confirm the results from non-destructive method. Through the extensive analysis, it was found that the main cause for discoloration is the formations of $Ag_2CO_3$ and $AgC_2H_3O_2$. Detailed mechanism for the formation of these particles was indentified through systematic studies.