Formation Of Colloidal Silver Research Articles

Photoinduced Formation of Colloidal Silver in Nitrocellulose Solutions Containing Titanium Alkoxides

The study shows the possibility of photo-induced reduction of silver nitrate and formation of stable colloidal silver particles in an isopropanol-N,N-dimethylacetamide solution of titanium alkoxide (polybutyl titanate) stabilized by nitrocellulose. It is established that titanium alkoxide and the products of its partial hydrolysis in the liquid composition play the role of a photocatalyst for the reduction of silver ions; the introduction of nitric or acetic acid additives to the composition significantly increases its photosensitivity. The films deposited from the liquid composition, previously irradiated with visible or UV light, consist of hydrated titanium dioxide and nitrocellulose with incorporated colloidal silver. Thermal treatment of the films at 150–245°C leads to the decomposition of nitrocellulose and an increase in the absorption by silver particles.

A GREEN SYNTHESIS OF COLLOIDAL SILVER NANOPARTICLES AND THEIR REACTION WITH OZONE

Colloidal silver nanoparticles were prepared by a conventional reduction of Ag + ions with NaBH 4 and with a novel approach using tannic acid (tannin) as reducing agent of Ag + ions. The formation of colloidal silver was followed by electronic absorption spectroscopy monitoring the growth of the surface-plasmon resonance band of the nanoparticles. Colloidal silver in tannin is more stable than that prepared with NaBH 4 because tannin exerts also a protective colloid function permitting to reach much higher colloidal silver concentration than in the case of NaBH 4 . Colloidal silver nanoparticles are readily reactive with ozone producing oxidized silver nanoparticles composed by argentic oxide (AgO). If the ozonation is conducted in gentle conditions the oxidized silver nanoparticles remain as colloidal suspension while if mechanical shaking is applied the particles coagulate and separate from the liquid medium as a precipitate.

Colloidal Nano Silver-Its Production Method, Properties, Standards and its Bio-efficacy as an Inorganic Antibiotic

The past 80 years has seen a plethora of different methods used to produce pretend colloidal silver that more often than not, consists mainly of ionic silver and other chemicals. Generally, little or no colloidal material is seen. Normally, only a ratio of Ionic to Colloidal Silver of 85:15% is quoted as the best obtainable result. Colloidal silver generally consists of nanosized clusters of silver atoms in an aqueous solution. We should not refer to them as particles. These atomic clusters are of a neutral polarity, but their suspension in the water causes a highly negative (interfacial) electrostatic charge called the Zeta potential. It is this highly negative Zeta potential of the clusters that causes a mutual repelling action resulting in an almost permanent suspension. This interfacial electrical charge is vulnerable to high temperatures and contamination by ionic substances. Even small amounts of ionic silver can interfere with this normal repelling action. Any of these contaminations may cause a drop in the interfacial charge causing aggregation and the release of attraction forces, such as the Van der Waals force, present in all materials. What follows is an uncontrolled growth of ever larger clusters to a point where gravity takes over and metallic silver drops out of the suspension. It has been determined that Colloidal Silver clusters should not be referred to as metallic, as at 10 nm size and below, they do not behave like a metal or controlled by standard physical laws. Because of this, nano sized silver clusters exhibit characteristics that are not present in bulk metallic silver. Some of these characteristics of nano sized colloidal silver can only be explained as being quantum phenomena. In this paper, we will show by using only the purest water and silver commercially available (99.998%), and by precisely controlling temperature, light and electrical conditions, and stable high grade, colloidal silver can be consistently produced using electrochemical principles. Some of our material has shown little signs of deterioration over many years. By also controlling the actual atomic cluster to a narrow size distribution and concentration, a highly effective antibacterial substance is created. That blue, indigo, violet and UV light plays such a most crucial role in the formation of colloidal silver has only recently been recognised by some scientists. It is ironic to realise that knowledge of the capabilities of short wavelength electromagnetic radiation, over and above 2.64 electron volt (eV), has been known for decades, even for nature and life itself. Few, if any, have paid any attention to the significance of these short wavelengths of light on colloidal silver production. One example of this is the role of UV on the skin promoting the production of Vitamin D. Similarly, UV exposure on silver halide deposited on B&W film produces a latent (photographic) image.

Sensitized photoreduction of silver ions in the presence of acetophenone

Aqueous silver perchlorate (AgClO 4)–acetophenone (AP)–sodium dodecylsulfate (SDS) solutions were photolyzed with near-UV light. The formation of colloidal silver and the photobleach of AP were caused by irradiation with 310 nm light, which was absorbed solely by AP (sensitized photoreduction). Gross features of the sensitized photoreduction of Ag + and the photobleach of AP were interpreted in terms of a simple reaction scheme entailing suitable combinations of the kinetics parameters. The kinetics parameters for the AgClO 4–AP–SDS solutions were compared with those for the AgClO 4–benzophenone–SDS solutions. It was noticed that the progress of the photoreaction was accompanied by the change in the extinction coefficient of the colloidal silver.

Formation of colloidal silver in the presence of a nonionic surfactant, Surfynol 465

The formation of colloidal silver in the presence of a nonionic surfactant, Surfynol 465, was studied at various temperatures. By simply mixing equal volumes of AgClO4 aq. (1–10 mmol kg−1) and Surfynol 465 aq., the colloidal silver was formed. The colloidal solution had well over ten times the amount of fine silver particles in the solution formed by the ordinary methods. The first factor to form the colloidal silver without aggregation was the molar ratio of Surfynol 465 to AgClO4, and the optimum ratio increased with increasing the concentration of AgClO4 or the temperature. In the fraction of colloidal silver collected through the gel filtration, Surfynol 465 was also found in the micellar state. From these results, it was suggested that Surfynol 465 was a protecting agent of colloidal silver as well as a reducing agent of AgClO4 in the similar manner to the case of colloidal gold.

ChemInform Abstract: Formation of Colloidal Silver by “Push‐Pull” Reduction of Ag+.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Formation of colloidal silver by "push-pull" reduction of silver(1+)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFormation of colloidal silver by "push-pull" reduction of silver(1+)Maritza Gutierrez and Arnim HengleinCite this: J. Phys. Chem. 1993, 97, 44, 11368–11370Publication Date (Print):November 1, 1993Publication History Published online1 May 2002Published inissue 1 November 1993https://doi.org/10.1021/j100146a003RIGHTS & PERMISSIONSArticle Views525Altmetric-Citations111LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts

Formation of colloidal silver in water by ultrasonic irradiation

Stable colloidal dispersions of silver were prepared by ultrasonic irradiations of aqueous AgClO4 or AgNO3 solutions in the presence of surfactants.

Colloidal silver formation at the surface of float glass

The formation of colloidal silver during the heating in air of silver films on float glass has been observed. The presence of colloidal silver gives to a yellow color and an absorption band centered at 400–420 nm. The results of this study indicate that the formation of colloidal silver is strongly dependent upon the concentration of stannous tin in the glass. The optical density of the absorption band induced in the glass is much greater for samples silvered on the tin-rich face of the glass and varies with the thermal history of the sample. Removal of the outer few micrometers of the glass surface results in a radical change in the amount of colloidal silver formed. Silver colloids are formed only if the sample is heated in an atmosphere containing oxygen, suggesting that the silver must be ionized before it will diffuse into the glass. The colloid formation process has an activation energy of approximately 30 kcal/mol, which is very near that reported for silver-sodium interdiffusion in similar glasses.

Photochemical Reaction of High-Molecular Silver Compounds

A WHITISH gelatinous precipitate is formed when a hydrophilic alkaline polyalkylacrylate solution of common formula: where R = CH3, C2H5, etc., Me = sodium, potassium or other alkaline elements, is added to a silver nitrate solution. This precipitate is dissolved slowly in a polymer excess to a probably complex silver salt solution. A freshly prepared precipitate is white; in light it quickly becomes lemon coloured and the complex solution which is formed becomes orange coloured. After a longer time in diffused daylight it turns into deep red and after some days it changes into dark violet. Various colours of the solution indicate that a photochemical decomposition occurs which is accompanied by the formation of colloidal silver at various degrees of dispersity. Direct sunlight and ultra-violet rays accelerate many times the photochemical decomposition of the high polymer silver compounds to silver sols, the most effective radiation being in the range of 450–300 mµ.