Colloidal silver consists of tiny silver particles in a liquid.
Colloidal silver is sometimes promoted on the internet as a dietary supplement; however, evidence supporting health-related claims is lacking.
Colloidal silver is used for wound healing, improving skin disorders, and preventing certain diseases.
CAS Number: 7440-22-4
EC Number: 231-131-3
Molecular Formula: Ag
Molecular Weight: 107.87
Synonymes:
7440-22-4, 7761-88-8, Silver, Silver Paste DGP80 TESM8020, Silver atomic spectroscopy standard concentrate 1.00 g Ag, Colloidal silver ink, Silver nanowires, Silver nitrate concentrate, Silver nitrate solution, Silver standard solution, Silver, dispersion, Silverjet DGH-55HTG, Silverjet DGH-55LT-25C, Silverjet DGP-40LT-15C, Silverjet DGP-40TE-20C, SunTronic® Silver
Colloidal silver has been used in a variety of ways.
However, Colloidal silver is not approved for medical use by the FDA and should not be consumed, injected, or inhaled.
Use of colloidal silver can result in short-term and long term side effects.
Colloidal silver, also known as silver proteins or colloidal silver proteins, is a suspension of tiny silver particles in liquid.
Although silver has been used for medicinal and health purposes for thousands of years, colloidal silver has recently become popular amongst wellness enthusiasts hoping to boost their overall health.
Colloidal silver is a suspension of tiny silver particles.
Commercial products are made by mixing silver, sodium hydroxide, and gelatin.
Homemade suspensions have also been made using different ingredients and an electrical current.
Most commonly, people swallow the suspension; however, Colloidal silver has also been inhaled using a nebulizer machine, and used topically on the skin and in the eyes.
Colloidal silver has even been used as a nasal spray.
Colloidal silver is a liquid suspension of microscopic particles of silver.
Colloidal silver has been promoted for its supposed antibacterial, antiviral, and antifungal properties.
Colloidal silver is one of the basic elements present in the earth's crust.
Colloidal silver is alloyed with many other metals to improve strength and hardness and to achieve corrosion resistance.
Colloidal silvers are one of the most commonly utilized nanomaterials due to their anti-microbial properties, high electrical conductivity, and optical properties.
Colloidal silvers (colloidal silver) have unique optical, electronic, and antibacterial properties, and are widely used in areas such as biosensing, photonics, electronics, and antimicrobial applications.
Colloidal silver is rare, but occurs naturally in the environment as a soft, “silver”-colored metal or as a white powdery compound (silver nitrate).
Metallic Colloidal silver and silver alloys are used to make jewelry, eating utensils, electronic equipment, and dental fillings.
Colloidal silvers of silver have been developed into meshes, bandages, and clothing as an antibacterial.
Colloidal silver is used in photographic materials, electric and electronic products, brazing alloys and solders, electroplated and sterling ware, as a catalyst, and in coinage.
Colloidal silvers are nanoparticles of silver, i.e. silver particles of between 1 nm and 100 nm in size.
The metal Colloidal silver is described as a white, lustrous solid.
In Colloidal silver is pure form it has the highest thermal and electrical conductivity and lowest contact resistance of all metals.
With the exception of gold, silver is the most malleable metal.
Colloidal silvers are nanoscale-sized particles composed of silver atoms.
Colloidal silvers, in particular, have attracted significant attention due to their distinct characteristics and potential applications.
Silver has no known functions or benefits in the body when taken by mouth, and Colloidal silver is not an essential mineral.
Colloidal silver products are often marketed as dietary supplements to take by mouth.
These products also come in forms to use on the skin.
Colloidal silver is a controversial alternative medicine.
A common form of Colloidal silver that is used to treat infections is silver nitrate.
Recent advancement in technology has introduced Colloidal silvers into the medical field.
Their small size and ability to induce cell death through multiple mechanisms makes them fantastic pharmacological candidates.
Colloidal silver is one of the earliest known metals.
Silver has no known physiologic or biologic function, though colloidal silver is widely sold in health food stores.
Colloidal silver has high thermal and electrical conductivity and resists oxidation in air that is devoid of hydrogen sulfide.
While frequently described as being 'silver' some are composed of a large percentage of silver oxide due to their large ratio of surface to bulk silver atoms.
Numerous shapes of Colloidal silvers can be constructed depending on the application at hand.
Commonly used Colloidal silvers are spherical, but diamond, octagonal, and thin sheets are also common.
Colloidal silver is widely used in many consumer products due to its unique optical, electrical, and thermal properties and extraordinarily efficient at absorbing and scattering light.
Colloidal silver has a face-centered cubic crystal structure.
Colloidal silver is a white metal, softer than copper and harder than gold.
When molten, Colloidal silver is luminescent and occludes oxygen, but the oxygen is released upon solidification.
As a conductor of heat and electricity, Colloidal silver is superior to all other metals.
Colloidal silver is soluble in HNO3 containing a trace of nitrate.
Colloidal silver is soluble in hot 80% H2SO4.
Colloidal silver is insoluble in HCl or acetic acid.
Colloidal silver is tarnished by H2S, soluble sulfides and many sulfur-containing organic substances (e.g., proteins).
Colloidal silver is not affected by air or H2O at ordinary temperatures, but at 200 C, a slight film of silver oxide is formed.
Colloidal silver is not affected by alkalis, either in solution or fused.
There are two stable, naturally occurring isotopes, 107Ag and 109Ag.
In addition, there are reported to be 25 less stable isotopes, ranging in half-life from 5 seconds to 253 days.
Colloidal silver is a white lustrous metal that is extremely ductile and malleable.
Colloidal silver does not oxidize in O2 by heating.
While frequently described as being 'silver' some are composed of a large percentage of silver oxide due to their large ratio of surface to bulk silver atoms.
Numerous shapes of nanoparticles can be constructed depending on the application at hand.
Commonly used Colloidal silvers are spherical, but diamond, octagonal, and thin sheets are also common.
Their extremely large surface area permits the coordination of a vast number of ligands.
The properties of Colloidal silvers applicable to human treatments are under investigation in laboratory and animal studies, assessing potential efficacy, biosafety, and biodistribution.
Most applications in biosensing and detection exploit the optical properties of Colloidal silvers, as conferred by the localized surface plasmon resonance effect.
That is, a specific wavelength (frequency) of incident light can induce collective oscillation of the surface electrons of Colloidal silvers.
The particular wavelength of the localized surface plasmon resonance is dependant on the Colloidal silver size, shape, and agglomeration state.
Colloidal silvers are the most common commercialized nano technological product on the market.
Due to its unique antibacterial properties, Colloidal silvers have been hailed as a breakthrough germ killing agent and have been incorporated into a number of consumer products such as clothing, kitchenware, toys and cosmetics.
Many consider silver to be more toxic than other metals when in nanoscale form and that these particles have a different toxicity mechanism compared to dissolved silver.
Colloidal silver can be synthesized using ethylene glycol as a reducing agent and PVP as a capping agent, in a polyol synthesis reaction (vide supra).
A typical synthesis using these reagents involves adding fresh Colloidal silver nitrate and PVP to a solution of ethylene glycol heated at 140 °C.
This procedure can actually be modified to produce another anisotropic silver nanostructure, nanowires, by just allowing the silver nitrate solution to age before using Colloidal silver in the synthesis.
By allowing the silver nitrate solution to age, the initial nanostructure formed during the synthesis is slightly different than that obtained with fresh silver nitrate, which influences the growth process, and therefore, the morphology of the final product.
Silver nanopaticles are widely incorporated into wound dressings, and are used as an antiseptic and disinfectant in medical applications and in consumer goods.
Colloidal silver becomes Ag2O3 in O3 and black Ag2S3 in S2 and H2S.
Colloidal silver is soluble in HNO3 and concentrated H2SO4.
Colloidal silver is not soluble in alkali.
Nanoscience and nanotechnology have now become the topic research that many developed.
Colloidal silver materials are developed in many applications because of their unique optical characteristic.
Colloidal silver is a noble metal, extensively used in SERS, photocatalysis and solar cells.
The surface of Colloidal silver can be functionalized to attain specific properties such as biocompatibility and vapor selectivity of sensors.
Iodized Colloidal silver foils and thin films find potential use as SERS-active metal substrates.
Cu substrates laminated with Ag foils, have compatible coefficient of thermal expansion (CTE), to be used for electronic packaging.
Their extremely large surface area permits the coordination of a vast number of ligands.
The properties of Colloidal silvers applicable to human treatments are under investigation in laboratory and animal studies, assessing potential efficacy, biosafety, and biodistribution.
Colloidal silvers are nanoparticles of silver in the range of 1 nm and 100 nm in size.
While frequently described as being 'Colloidal silver' some are composed of a large percentage of silver oxide due to their large ratio of surface-to-bulk silver atoms.
As studies of Colloidal silvers improve, several Colloidal silvers medical applications have been developed to help prevent the onset of infection and promote faster wound healing.
Colloidal silvers are materials with dimensions typically in the range of 1 to 100 nanometers.
At this scale, materials often exhibit unique and enhanced properties compared to their bulk counterparts.
Colloidal silvers have a high surface area per unit mass and release a continuous level of silver ions into their environment.
Colloidal silvers exhibit catalytic activity, making them useful in certain chemical reactions and processes.
This property is of interest in fields such as catalysis and environmental remediation.
Colloidal silvers display unique optical properties, including the ability to interact with light in ways that depend on their size and shape.
This has led to applications in sensors, imaging, and as components in optical devices.
Due to the conductive nature of silver, nanoparticles made from silver can exhibit enhanced electrical conductivity.
This property is advantageous in applications related to electronics and sensors.
The interaction of light with the electrons in Colloidal silvers leads to a phenomenon known as surface plasmon resonance (SPR).
This optical effect is widely exploited in sensing applications.
Colloidal silvers have been investigated for various biomedical applications, including drug delivery systems, imaging agents, and as components in diagnostic tools.
Colloidal silvers are used in the formulation of conductive inks and coatings for applications in printed electronics, flexible electronics, and RFID tags.
Colloidal silvers are incorporated into textiles and fabrics to impart antimicrobial properties, making them useful for applications such as antibacterial clothing and wound dressings.
Incorporation of silver particles into plastics, composites, and adhesives increases the electrical conductivity of the material.
Silver pastes and epoxies are widely utilized in the electronics industries.
Colloidal silver based inks are used to print flexible electronics and have the advantage that the melting point of the small Colloidal silvers in the ink is reduced by hundreds of degrees compared to bulk silver.
When scintered, these Colloidal silver based inks have excellent conductivity.
Colloidal silvers have attract increasing attention for the wide range of applications in biomedicine.
Colloidal silvers, generally smaller than 100 nm and contain 20–15,000 silver atoms, have distinct physical, chemical and biological properties compared to their bulk parent materials.
The optical, thermal, and catalytic properties of Colloidal silvers are strongly influenced by their size and shape.
Additionally, owning to their broad-spectrum antimicrobial ability, Colloidal silvers have also become the most widely used sterilizing nanomaterials in consuming and medical products, for instance, textiles, food storage bags, refrigerator surfaces, and personal care products.
Colloidal silvers are those having diameters of nanometer size.
With the advent of modern technology, humans can make nano-sized particles that were not present in nature.
Manufactured nanomaterials are materials with diameters of nanometer size, while nanotechnology is one of the fastest growing sectors of the hi-tech economy.
The application of nanotechnology has recently been extended to areas in medicine, biotechnology, materials and process development, energy and the environment.
Colloidal silver is the 66th most abundant element on the Earth, which means Colloidal silver is found at about0.05 ppm in the Earth’s crust.
Mining silver requires the movement of many tons of ore torecover small amounts of the metal.
Nevertheless, Colloidal silver is 10 times more abundant than gold and though silver is sometimes found as a free metal in nature, mostly Colloidal silver is mixed with theores of other metals.
When found pure, Colloidal silver is referred to as “native silver.”
Colloidal silver’s major ores areargentite (silver sulfide, Ag2S) and horn silver (silver chloride, AgCl).
Colloidal silver can also be recovered throughthe chemical treatment of a variety of ores.
Colloidal silvers have unique optical properties because they support surface plasmons.
At specific wavelengths of light the surface plasmons are driven into resonance and strongly absorb or scatter incident light.
This effect is so strong that Colloidal silver allows for individual nanoparticles as small as 20 nm in diameter to be imaged using a conventional dark field microscope.
This strong coupling of metal nanostructures with light is the basis for the new field of plasmonics.
Applications of plasmonic Colloidal silvers include biomedical labels, sensors, and detectors.
Colloidal silver is also the basis for analysis techniques such as Surface Enhanced Raman Spectroscopy (SERS) and Surface Enhanced Fluorescent Spectroscopy.
There are many ways Colloidal silvers can be synthesized; one method is through monosaccharides.
This includes glucose, fructose, maltose, maltodextrin, etc., but not sucrose.
Colloidal silver is also a simple method to reduce silver ions back to Colloidal silvers as it usually involves a one-step process.
There have been methods that indicated that these reducing sugars are essential to the formation of Colloidal silvers.
Many studies indicated that this method of green synthesis, specifically using Cacumen platycladi extract, enabled the reduction of silver.
Additionally, the size of the Colloidal silver could be controlled depending on the concentration of the extract.
The studies indicate that the higher concentrations correlated to an increased number of Colloidal silvers.
Smaller Colloidal silvers were formed at high pH levels due to the concentration of the monosaccharides.
Another method of Colloidal silver synthesis includes the use of reducing sugars with alkali starch and silver nitrate.
The reducing sugars have free aldehyde and ketone groups, which enable them to be oxidized into gluconate.
However, most Colloidal silver isrecovered as a by-product of the refining of copper, lead, gold, and zinc ores.
Colloidal silvers have been explored for their potential in water treatment and purification due to their antimicrobial properties.
The silver ions are bioactive and have broad spectrum antimicrobial properties against a wide range of bacteria.
By controlling the size, shape, surface and agglomeration state of the nanoparticles, specific silver ion release profiles can be developed for a given application.
Colloidal silvers typically have dimensions ranging from 1 to 100 nanometers.
The size and shape of these particles can influence their physical, chemical, and optical properties.
One of the notable features of Colloidal silvers is their strong antibacterial and antimicrobial activity.
The Colloidal silver must have a free ketone group because in order to act as a reducing agent Colloidal silver first undergoes tautomerization.
When inhaled, Colloidal silvers can go deeper into the lungs reaching more sensitive areas.
The most common methods for Colloidal silver synthesis fall under the category of wet chemistry, or the nucleation of particles within a solution.
This nucleation occurs when a Colloidal silver ion complex, usually AgNO3 or AgClO4, is reduced to colloidal Ag in the presence of a reducing agent.
When the concentration increases enough, dissolved metallic Colloidal silver ions bind together to form a stable surface.
The surface is energetically unfavorable when the cluster is small, because the energy gained by decreasing the concentration of dissolved particles is not as high as the energy lost from creating a new surface.
When the cluster reaches a certain size, known as the critical radius, Colloidal silver becomes energetically favorable, and thus stable enough to continue to grow.
This nucleus then remains in the system and grows as more Colloidal silver atoms diffuse through the solution and attach to the surface.
When the dissolved concentration of atomic Colloidal silver decreases enough, it is no longer possible for enough atoms to bind together to form a stable nucleus.
The most common capping ligands are trisodium citrate and polyvinylpyrrolidone (PVP), but many others are also used in varying conditions to synthesize particles with particular sizes, shapes, and surface properties.
There are many different wet synthesis methods, including the use of reducing sugars, citrate reduction, reduction via sodium borohydride, the Colloidal silver mirror reaction, the polyol process, seed-mediated growth, and light-mediated growth.
Each of these methods, or a combination of methods, will offer differing degrees of control over the size distribution as well as distributions of geometric arrangements of the nanoparticle.
A new, very promising wet-chemical technique was found by Elsupikhe et al. (2015).
They have developed a green ultrasonically-assisted synthesis.
Under ultrasound treatment, Colloidal silvers (AgNP) are synthesized with κ-carrageenan as a natural stabilizer.
The reaction is performed at ambient temperature and produces Colloidal silvers with fcc crystal structure without impurities.
The concentration of κ-carrageenan is used to influence particle size distribution of the AgNPs.
The synthesis of Colloidal silvers by sodium borohydride (NaBH4) reduction occurs by the following reaction:
Ag+ + BH4− + 3 H2O → Ag0 +B(OH)3 +3.5 H2
The reduced metal atoms will form nanoparticle nuclei.
Overall, this process is similar to the above reduction method using citrate.
The benefit of using sodium borohydride is increased monodispersity of the final particle population.
The reason for the increased Colloidal silver when using NaBH4 is that it is a stronger reducing agent than citrate.
The impact of reducing agent strength can be seen by inspecting a LaMer diagram which describes the nucleation and growth of nanoparticles.
When Colloidal silver nitrate (AgNO3) is reduced by a weak reducing agent like citrate, the reduction rate is lower which means that new nuclei are forming and old nuclei are growing concurrently.
This is the reason that the citrate reaction has low monodispersity.
Because NaBH4 is a much stronger reducing agent, the concentration of silver nitrate is reduced rapidly which shortens the time during which new nuclei form and grow concurrently yielding a monodispersed population of Colloidal silvers.
Particles formed by reduction must have their surfaces stabilized to prevent undesirable particle agglomeration (when multiple particles bond together), growth, or coarsening.
The driving force for these phenomena is the minimization of surface energy (nanoparticles have a large surface to volume ratio).
This tendency to reduce surface energy in the system can be counteracted by adding species which will adsorb to the surface of the nanoparticles and lowers the activity of the particle surface thus preventing particle agglomeration according to the DLVO theory and preventing growth by occupying attachment sites for metal atoms.
Chemical species that adsorb to the surface of Colloidal silvers are called ligands.
Some of these surface stabilizing species are:
NaBH4 in large amounts, poly(vinyl pyrrolidone) (PVP), sodium dodecyl sulfate (SDS), and/or dodecanethiol.
Once the particles have been formed in solution they must be separated and collected.
There are several general methods to remove nanoparticles from solution, including evaporating the solvent phase or the addition of chemicals to the solution that lower the solubility of the nanoparticles in the solution.
Both methods force the precipitation of the Colloidal silvers.
The polyol process is a particularly useful method because Colloidal silver yields a high degree of control over both the size and geometry of the resulting Colloidal silvers.
At this nucleation threshold, new Colloidal silvers stop being formed, and the remaining dissolved silver is absorbed by diffusion into the growing nanoparticles in the solution.
As the particles grow, other molecules in the solution diffuse and attach to the surface.
This process stabilizes the surface energy of the particle and blocks new Colloidal silver ions from reaching the surface.
The attachment of these capping/stabilizing agents slows and eventually stops the growth of the particle.
In addition, if the aldehydes are bound, Colloidal silver will be stuck in cyclic form and cannot act as a reducing agent.
For example, glucose has an aldehyde functional group that is able to reduce Colloidal silver cations to silver atoms and is then oxidized to gluconic acid.
The reaction for the sugars to be oxidized occurs in aqueous solutions.
The polyol process is highly sensitive to reaction conditions such as temperature, chemical environment, and concentration of substrates.
Therefore, by changing these variables, various sizes and geometries can be selected for such as quasi-spheres, pyramids, spheres, and wires.
Further study has examined the mechanism for this process as well as resulting geometries under various reaction conditions in greater detail.
Colloidal silvers can be synthesized in a variety of non-spherical (anisotropic) shapes.
Because Colloidal silver, like other noble metals, exhibits a size and shape dependent optical effect known as localized surface plasmon resonance (LSPR) at the nanoscale, the ability to synthesize Ag nanoparticles in different shapes vastly increases the ability to tune their optical behavior.
For example, the wavelength at which LSPR occurs for a nanoparticle of one morphology (e.g. a sphere) will be different if that sphere is changed into a different shape.
This shape dependence allows a Colloidal silver to experience optical enhancement at a range of different wavelengths, even by keeping the size relatively constant, just by changing Colloidal silver shape.
This aspect can be exploited in synthesis to promote change in shape of nanoparticles through light interaction.
The applications of this shape-exploited expansion of optical behavior range from developing more sensitive biosensors to increasing the longevity of textiles.
Colloidal silvers have been shown to have synergistic antibacterial activity with commonly used antibiotics such as; penicillin G, ampicillin, erythromycin, clindamycin, and vancomycin against E. coli and S. aureus.
Furthermore, synergistic antibacterial activity has been reported between Colloidal silvers and hydrogen peroxide causing this combination to exert significantly enhanced bactericidal effect against both Gram negative and Gram positive bacteria.
This antibacterial synergy between Colloidal silvers and hydrogen peroxide can be possibly attributed to a Fenton-like reaction that generates highly reactive oxygen species such as hydroxyl radicals.
Colloidal silvers can prevent bacteria from growing on or adhering to the surface.
This can be especially useful in surgical settings where all surfaces in contact with the patient must be sterile.
Colloidal silvers can be incorporated on many types of surfaces including metals, plastic, and glass.
In medical equipment, Colloidal silver has been shown that Colloidal silvers lower the bacterial count on devices used compared to old techniques.
However, the problem arises when the procedure is over and a new one must be done.
In the process of washing the instruments a large portion of the Colloidal silvers become less effective due to the loss of silver ions.
They are more commonly used in skin grafts for burn victims as the Colloidal silvers embedded with the graft provide better antimicrobial activity and result in significantly less scarring of the victim.
These new applications are direct decedents of older practices that used silver nitrate to treat conditions such as skin ulcers.
Now, Colloidal silvers are used in bandages and patches to help heal certain burns and wounds.
An alternative approach is to use AgNP to sterilise biological dressings (for example, tilapia fish skin) for burn and wound management.
In this method, polyvinylpyrrolidone (PVP) is dissolved in water by sonication and mixed with silver colloid particles.
Active stirring ensures the PVP has adsorbed to the nanoparticle surface.
Centrifuging separates the PVP coated nanoparticles which are then transferred to a solution of ethanol to be centrifuged further and placed in a solution of ammonia, ethanol and Si(OEt4) (TES).
Stirring for twelve hours results in the silica shell being formed consisting of a surrounding layer of silicon oxide with an ether linkage available to add functionality.
Varying the amount of TES allows for different thicknesses of shells formed.
This technique is popular due to the ability to add a variety of functionality to the exposed silica surface.
Colloidal silver have unique physical, chemical and optical properties that are being leveraged for a wide variety of applications.
A resurgence of interest in the utility of Colloidal silver as a broad based antimicrobial agent has led to the development of hundreds of products that incorporate Colloidal silvers to prevent bacterial growth on surfaces and in clothing.
The optical properties of Colloidal silvers are of interest due to the strong coupling of the Colloidal silvers to specific wavelengths of incident light.
This gives them a tunable optical response, and can be utilized to develop ultra-bright reporter molecules, highly efficient thermal absorbers, and nanoscale “antennas” that amplify the strength of the local electromagnetic field to detect changes to the nanoparticle environment.
Colloidal silver is said to be a “key technology of the 21st century”, which is the result of its interdisciplinary nature.
Colloidal silvers are some of the most widely used nanomaterials in commerce, with numerous uses in consumer and medical products.
Workers who produce or use Colloidal silvers are potentially exposed to those materials in the workplace.
Previous authoritative assessments of occupational exposure to silver did not account for particle size.
In studies that involved human cells, Colloidal silvers were associated with toxicity (cell death and DNA damage) that varied according to the size of the particles.
In animals exposed to Colloidal silvers by inhalation or other routes of exposure, silver tissue concentrations were elevated in all organs tested.
Exposure to silver nanomaterials in animals was associated with decreased lung function, inflamed lung tissue, and histopathological (microscopic tissue) changes in the liver and kidney.
In the relatively few studies that compared the effects of exposure to nanoscale or microscale silver, nanoscale particles had greater uptake and toxicity than did microscale particles.
Colloidal silvers of different shapes and sizes are synthesized through chemical, physical, and green methods.
Obtained nanoparticles are generally utilized in the medical industry, catalytic applications, sensors, and special displays.
Colloidal silvers have been an important component of various different applications for a very long time.
Colloidal silvers are explored for their potential use in food packaging materials due to their antimicrobial properties.
They may help extend the shelf life of packaged foods by inhibiting the growth of microorganisms.
Colloidal silvers are utilized in the fabrication of solar cells and other photovoltaic devices.
They can enhance light absorption and electron transport within the devices, contributing to improved efficiency.
In the field of medicine, Colloidal silvers are being investigated for their use in photothermal therapy.
When exposed to specific wavelengths of light, they can generate heat, which may be utilized for targeted treatment of cancer cells.
Some studies suggest that Colloidal silvers may exhibit antiviral properties, making them a subject of interest in the development of antiviral drugs or materials.
Colloidal silvers can be incorporated into textile coatings to provide UV protection.
This is particularly useful in outdoor clothing and fabrics to shield against harmful ultraviolet radiation.
Colloidal silvers are employed in the production of conductive inks for printed electronics and flexible displays.
Their conductivity and compatibility with flexible substrates make them valuable in these applications.
Due to their antimicrobial properties, Colloidal silvers are explored for use in air and water purification systems.
They can help eliminate or reduce the presence of harmful microorganisms.
Colloidal silvers are incorporated into sensors for various applications, including gas sensors, biosensors, and environmental sensors.
Their unique optical and electrical properties make them suitable for sensing platforms.
Colloidal silvers may be included in certain cosmetic and personal care products for their potential antibacterial and preservative properties.
In the medical field, efforts are made to develop biocompatible Colloidal silvers for applications such as drug delivery and imaging.
These nanoparticles aim to interact safely with biological systems.
Colloidal silvers are used in the formulation of conductive inks for printed radio-frequency identification (RFID) tags.
This application is relevant in the field of logistics and inventory tracking.
The capping agent is also not present when heated.
Colloidal silvers can become airborne easily due to their size and mass.
Colloidal silver is located in group 11 (IB) of period 5, between copper (Cu) above Colloidal silver in period 4 andgold (Au) below it in period 6.
Colloidal silver products have not undergone safety studies and are not recommended by the FDA.
In addition, there have been serious adverse effects such as seizures, psychosis, neuropathy (burning pain usually in hands and feet), and even deaths reported from colloidal silver use.
Because there is no information to suggest colloidal silver is effective for the treatment of any condition, the risks of using Colloidal silver outweigh the benefits.
Colloidal silver is only slightly harder than gold.
Colloidal silver is insoluble in water, but it will dissolve in hot concentrated acids.
Freshly exposed silver has a mirror-like shine thatslowly darkens as a thin coat of tarnish forms on Colloidal silver surface (from the small amount ofnatural hydrogen sulfide in the air to form silver sulfide, AgS).
Colloidal silvers can also be produced via γ-irradiation using polysaccharide alginate as stabilizer, and photochemical reduction.
A relatively new biological method can be used to make gold Colloidal silvers by dissolving gold in sodium chloride solution, using natural chitosan without any stabilizer and reductant.
Colloidal silver’s modern chemical symbol (Ag) is derived from its Latin word argentum, which means silver.
The word “silver” is from the Anglo-Saxon world “siolfor.”
Ancients who first refined and worked with Colloidal silver used the symbol of a crescent moon to represent the metal.
Colloidal silvers can undergo coating techniques that offer a uniform functionalized surface to which substrates can be added.
When the Colloidal silver is coated, for example, in silica the surface exists as silicic acid.
Colloidal silvers can thus be added through stable ether and ester linkages that are not degraded immediately by natural metabolic enzymes.
Recent chemotherapeutic applications have designed anti cancer drugs with a photo cleavable linker, such as an ortho-nitrobenzyl bridge, attaching Colloidal silver to the substrate on the nanoparticle surface.
The low toxicity Colloidal silver complex can remain viable under metabolic attack for the time necessary to be distributed throughout the bodies systems.
If a cancerous tumor is being targeted for treatment, ultraviolet light can be introduced over the tumor region.
The electromagnetic energy of the light causes the photo responsive linker to break between the drug and the nanoparticle substrate.
The drug is now cleaved and released in an unaltered active form to act on the cancerous tumor cells.
Advantages anticipated for this method is that the drug is transported without highly toxic compounds, the drug is released without harmful radiation or relying on a specific chemical reaction to occur and the drug can be selectively released at a target tissue.
Colloidal silver is somewhat rare and is considered a commercially precious metal with many uses.
Pure Colloidal silver is too soft and usually too expensive for many commercial uses, and thus Colloidal silver isalloyed with other metals, usually copper, making it not only stronger but also less expensive.
The purity of Colloidal silver is expressed in the term “fitness,” which describes the amount of silverin the item.
Fitness is just a multiple of 10 times the Colloidal silver content in an item.
For instance,sterling Colloidal silver should be 93% (or at least 92.5%) pure silver and 7% copper or some othermetal.
The fitness rating for pure Colloidal silver is 1000.
Therefore, the rating for sterling Colloidal silver is 930,and most sliver jewelry is rated at about 800.
This is another way of saying that most Colloidal silver jewelry is about 20% copper or other less valuable metal.
Many people are fooled when they buy Mexican or German silver jewelry, thinking theyare purchasing a semiprecious metal.
These forms of “Colloidal silver” jewelry go under many names,including Mexican silver, German silver, Afghan silver, Austrian silver, Brazilian silver, Nevadasilver, Sonara silver, Tyrol silver, Venetian silver, or just the name “silver” with quotes aroundit.
None of these jewelry items, under these names or under any other names, contain anysilver.
These metals are alloys of copper, nickel, and zinc.
A transition metal that occurs native and as the sulfide (Ag2S) and chloride (AgCl).
Colloidal silver is extracted as a by-product in refining copper and lead ores.
Colloidal silver darkens in air due to the formation of silver sulfide.
Colloidal silver is used in coinage alloys, tableware, and jewelry.
Of all the metals, Colloidal silver isthe best conductor of heat and electricity.
This property determines much of Colloidal silver commercialusefulness.
Colloidal silver is melting point is 961.93°C.
Colloidal silver boiling point is 2,212°C.
Colloidal silver density is10.50 g/cm3.
The beneficial effects of Colloidal silvers are also manifested in their action against inflammation and suppression of tumor growth.
Colloidal silvers can induce apoptosis, or programmed cell death, in tumor cells.
The activity of Colloidal silvers in the human body can be used for imaging of living cells and tissues, both in diagnosis and research.
Colloidal silvers are also used in biosensors, can detect tumor cells, and have potential in phototherapy, where they absorb radiation, heat up and selectively eliminate selected cells.
Colloidal silvers are highly commercial due to properties such as good conductivity, chemical stability, catalytic activity, and their antimicrobial activity.
Due to their properties, they are commonly used in medical and electrical applications.
Colloidal silver compounds are used in photography symbol:
Ag
m.p. 961.93°C
b.p. 2212°C
r.d. 10.5 (20°C)
p.n. 47
r.a.m. 107.8682.
Synthetic protocols for Colloidal silver production can be modified to produce Colloidal silvers with non-spherical geometries and also to functionalize nanoparticles with different materials, such as silica.
Creating Colloidal silvers of different shapes and surface coatings allows for greater control over their size-specific properties.
There are instances in which Colloidal silvers and colloidal silver are used in consumer goods.
Samsung for example claimed that the use of Colloidal silvers in washing machines would help to sterilize clothes and water during the washing and rinsing functions, and allow clothes to be cleaned without the need for hot water.
The nanoparticles in these appliances are synthesized using electrolysis.
Through electrolysis, Colloidal silver is extracted from metal plates and then turned into Colloidal silvers by a reduction agent.
This method avoids the drying, cleaning, and re-dispersion processes, which are generally required with alternative colloidal synthesis methods.
Importantly, the electrolysis strategy also decreases the production cost of Ag nanoparticles, making these washing machines more affordable to manufacture.
Colloidal silver can form explosive salts with azidrine.
Ammonia forms explosive compounds with gold, mercury, or Silver.
Acetylene and ammonia can form explosive Silver salts in contact with Ag.
Dust may form explosive mixture with air.
Powders are incompatible with strong oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions.
Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides May react and/or form dangerous or explosive compounds, with acetylene, ammonia, halogens, hydrogen peroxide; bromoazide, concentrated or strong acids, oxalic acid, tartaric acid, chlorine trifluoride, ethyleneimine.
Factors contributing toward Colloidal silvers market growth include rise in demand for Colloidal silvers for anti-microbial applications and increase in demand from electronics sector.
Colloidal silvers are investigated in the field of tissue engineering for their potential to support cell growth and enhance the properties of scaffolds used in regenerative medicine.
In marine applications, Colloidal silvers are used in anti-fouling coatings on ship hulls.
They help prevent the accumulation of marine organisms, reducing drag and improving fuel efficiency.
Colloidal silvers are explored for their potential use in pesticide formulations.
Their antimicrobial properties could be leveraged for crop protection and pest control.
Colloidal silvers are employed in the development of electrochemical sensors for detecting various analytes.
These sensors find applications in fields such as environmental monitoring and healthcare.
Colloidal silvers can be utilized in the fabrication of sensors for detecting hydrogen peroxide.
This application is relevant in fields such as clinical diagnostics and industrial processes.
Colloidal silvers are studied for their potential application in energy storage devices, such as batteries and supercapacitors, where their unique properties can influence performance.
An early, and very common, method for synthesizing Colloidal silvers is citrate reduction.
This method was first recorded by M. C. Lea, who successfully produced a citrate-stabilized silver colloid in 1889.
Citrate reduction involves the reduction of a silver source particle, usually AgNO3 or AgClO4, to colloidal silver using trisodium citrate, Na3C6H5O7.
The synthesis is usually performed at an elevated temperature (~100 °C) to maximize the monodispersity (uniformity in both size and shape) of the particle.
In this method, the citrate ion traditionally acts as both the reducing agent and the capping ligand, making Colloidal silver a useful process for AgNP production due to its relative ease and short reaction time.
However, the silver particles formed may exhibit broad size distributions and form several different particle geometries simultaneously.
The addition of stronger reducing agents to the reaction is often used to synthesize particles of a more uniform size and shape.
Colloidal silver mirror reaction involves the conversion of Colloidal silver nitrate to Ag(NH3)OH.
Ag(NH3)OH is subsequently reduced into colloidal silver using an aldehyde containing molecule such as a sugar.
The silver mirror reaction is as follows:
2(Ag(NH3)2)+ + RCHO + 2OH− → RCOOH + 2Ag + 4NH3.
The size and shape of the Colloidal silvers produced are difficult to control and often have wide distributions.
However, this method is often used to apply thin coatings of Colloidal silver particles onto surfaces and further study into producing more uniformly sized nanoparticles is being done.
The biological synthesis of Colloidal silvers has provided a means for improved techniques compared to the traditional methods that call for the use of harmful reducing agents like sodium borohydride.
Many of these methods could improve their environmental footprint by replacing these relatively strong reducing agents.
The commonly used biological methods are using plant or fruit extracts, fungi, and even animal parts like insect wing extract.
The problems with the chemical production of Colloidal silvers is usually involves high cost and the longevity of the particles is short lived due to aggregation.
The harshness of standard chemical methods has sparked the use of using biological organisms to reduce silver ions in solution into colloidal Colloidal silvers.
Colloidal silvers can provide a means to overcome MDR.
In general, when using a targeting agent to deliver nanocarriers to cancer cells, Colloidal silver is imperative that the agent binds with high selectivity to molecules that are uniquely expressed on the cell surface.
Hence NPs can be designed with proteins that specifically detect drug resistant cells with overexpressed transporter proteins on their surface.
Colloidal silver a pitfall of the commonly used nano-drug delivery systems is that free drugs that are released from the nanocarriers into the cytosol get exposed to the MDR transporters once again, and are exported.
To solve this, 8 nm Colloidal silvers were modified by the addition of trans-activating transcriptional activator (TAT), derived from the HIV-1 virus, which acts as a cell-penetrating peptide (CPP).
Generally, AgNP effectiveness is limited due to the lack of efficient cellular uptake; however, CPP-modification has become one of the most efficient methods for improving intracellular delivery of Colloidal silvers.
Once ingested, the export of the AgNP is prevented based on a size exclusion.
The concept is simple: the nanoparticles are too large to be effluxed by the MDR transporters, because the efflux function is strictly subjected to the size of Colloidal silver substrates, which is generally limited to a range of 300-2000 Da.
Thereby the Colloidal silvers remain insusceptible to the efflux, providing a means to accumulate in high concentrations.
In addition, increased demand from pharmaceutical industry as Colloidal silver is used in the field of biomarkers, biosensors, implant technology, tissue engineering, nanorobots & nanomedicine, and image enhancement devices.
The bactericidal activity of Colloidal silvers is due to the silver cations, which have the potential to disrupt physiological activity of microbes such as bacteria.
Growth in concerns regarding environmental impact and toxicity of Colloidal silvers is hindering the Colloidal silvers market.
Furthermore, high Colloidal silver product prices are likely to hinder market growth during the forecast period.
On the contrary, rise in trend of biological synthesis method is expected to create lucrative opportunities for the market during the forecast period.
Colloidal silvers are investigated for their potential role in drug delivery systems.
They can be designed to carry therapeutic agents and release them in a controlled manner, offering targeted drug delivery.
Colloidal silvers can exhibit photocatalytic activity, which means they can accelerate chemical reactions under light exposure.
This property is explored in applications like environmental remediation and water treatment.
In the field of electronics, Colloidal silvers are used to create flexible and transparent conductive films.
These films have applications in flexible electronics, touch screens, and electronic displays.
Colloidal silvers are integrated into textiles to impart anti-odor properties by inhibiting the growth of odor-causing bacteria.
This application is common in sportswear and undergarments.
Colloidal silvers are incorporated into various nanocomposite materials to enhance their mechanical, thermal, and electrical properties.
These nanocomposites find applications in materials science and engineering.
Some studies explore the use of Colloidal silvers as contrast agents in magnetic resonance imaging (MRI) for medical diagnostics.
Colloidal silvers can be very effective against fungal infections that are otherwise difficult to treat.
This is of great importance for patients with weakened immunity who are especially vulnerable to fungi.
These Colloidal silvers not only suppress pathogenic fungi, including yeasts, but also fungi that grow in households, such as various mold species.
Colloidal silver reacts violently with chlorine trifluoride (in the presence of carbon).
Bromoazide explodes on contact with Silver foil.
Acetylene forms an insoluble acetylide with Silver.
When Colloidal silver is treated with nitric acid in the presence of ethyl alcohol, Silver fulminate, which can detonated may be formed.
Ethyleneimine forms explosive compounds with Colloidal silver, hence Silver solder should not be used to fabricate equipment for handling ethyleneimine.
Finely divided Silver and strong solutions of hydrogen peroxide may explode.
Colloidal silvers optical properties are also dependent on the nanoparticle size.
Smaller nanospheres absorb light and have peaks near to 400 nm, and larger nanoparticles have increased scattering to gives peaks that broaden and shift towards longer wavelengths.
Larger shifts into the infrared region of the electromagnetic spectrum are achieved by changing the nanoparticles shape to rods or plates.
Colloidal silvers can be synthesized by a variety of different techniques that are chemical, physical or biological.
The most common method for making colloidal gold is by a chemical citrate reduction method, but gold nanoparticles can also be grown by being encapsulated and immersed in polyethylene glycol dendrimers before being reduced by formaldehyde under near infra-red treatment.
Uses of Colloidal silver:
Because silver has antibacterial properties, colloidal silver was used to treat skin infections before antibiotics were available.
More recently, colloidal silver has been used to treat a variety of infections, including COVID-19, to boost the immune system, and decrease inflammation.
Colloidal silver is important to know, there is no clinical evidence to support the efficacy of colloidal silver and the U.S. Food and Drug Administration (FDA) recommends against Colloidal silver use.
There are some topical silver creams and other topical products that are approved by the FDA to prevent and treat infections.
These are different than colloidal silver.
Several of Colloidal silver compounds were not only useful but even essential for the predigital photographicindustry.
Colloidal silver has no known active biological role in the human body, and the levels of Ag+ within the body are below detection limits.
The metal has been used for thousands of years mainly as ornamental metal or for coins.
Furthermore, Colloidal silver has been used for medicinal purposes since 1000 BC.
Colloidal silver was known that water would keep fresh if it was kept in a silver pitcher; for example, Alexander the Great (356–323 BC) used to transport his water supplies in Colloidal silver pitchers during the Persian War.
A piece of Colloidal silver was also used, for example, to keep milk fresh, before any household refrigeration was developed.
In 1869, Ravelin proved that Colloidal silver in low doses acts as an antimicrobial.
Around the same time, the Swiss botanist showed that already at very low concentration Ag+ can kill the green algae spirogyra in fresh water.
This work inspired the gynaecologist Crede to recommended use of AgNO3 drops on new born children with conjunctivitis.
Using Colloidal silvers for catalysis has been gaining attention in recent years.
Although the most common applications are for medicinal or antibacterial purposes, Colloidal silvers have been demonstrated to show catalytic redox properties for dyes, benzene, and carbon monoxide.
Other untested compounds may use Colloidal silvers for catalysis, but the field is not fully explored.
Colloidal silvers supported on aerogel are advantageous due to the higher number of active sites.
Several of the Colloidal silver salts, such as silver nitrate, silver bromide, and silverchloride, are sensitive to light and, thus, when mixed with a gel-type coating on photographicfilm or paper, can be used to form light images.
Most of the Colloidal silver used in the United Statesis used in photography.
Photochromic (transition) eyeglasses that darken as they are exposed to sunlight have asmall amount of silver chloride imbedded in the glass that forms a thin layer of metallic silverthat darkens the lens when struck by sunlight.
This photosensitive chemical activity is thenreversed when the eyeglasses are removed from the light.
Colloidal silver reversal results from asmall amount of copper ions placed in the glass.
This reaction is repeated each time the lensesare exposed to sunlight.
This malleable white metal is found as argentite (Ag2S) and horn silver (AgCl) or in lead and copper ore.
Colloidal silvers coated with a thin layer of elemental silver and fumed with iodine were used by Niépce and Daguerre.
Aside from the heliograph and physautotype, Colloidal silver halide compounds were the basis of all photographic processes used in the camera and most of the printing processes during the 19th century.
Colloidal silver are one of the most fascinating, promising and widely used nano materials, particularly for their interesting antibacterial, antiviral and antifungal effects.
However, their potential uses are much wider.
Colloidal silvers are used in antibacterial products, industrial production, catalysis, household products and consumer goods.
Colloidal silver was used to treat infections and wounds before antibiotics became available.
Colloidal silvers are commonly used in biomedical and medical applications due to their antibacterial, antifungal, antiviral, anti-inflammatory, and anti-tumor effects.
Due to their favorable surface-to-volume ratio and crystal structure, nano silver particles are a promising alternative to antibiotics.
They can penetrate bacterial walls and effectively deal with bacterial biofilms and mucous coatings, which are usually well-protected environments for bacteria.
Colloidal silver are one of the most commonly used nanomaterials because of their high electrical conductivity, optical properties, and anti-microbial properties.
The biological activity of Colloidal silvers depends on factors such as particle composition, size distribution, surface chemistry, size; shape, coating/capping, particle morphology, dissolution rate, agglomeration, efficiency of ion release, and particle reactivity in solution.
Colloidal silvers have found a wide range of applications including their use as catalysts, as optical sensors of zeptomole (10−21) concentrations, in textile engineering, in electronics, in optics, as anti-reflection coatings, and most importantly in the medical field as a bactericidal and therapeutic agent.
Colloidal silver is used in the formulation of dental resin composites, in coatings of medical devices, as a bactericidal coating in water filters, as an antimicrobial agent in air sanitizer sprays, pillows, respirators, socks, keyboards, detergents, soaps, shampoos, toothpastes, washing machines and many other consumer products, in bone cement and in many wound dressings.
Colloidal silvers are also commonly used in colloidal solutions to enhance Raman spectroscopy.
The size and shape of nanoparticles have been shown to affect the enhancement.
Colloidal silvers are the most common shape of nanoparticles, but other shapes such as nanostars, nanocubes, nanorods and nanowires can be produced through a polymer-mediated polyol process.
Colloidal silvers can also be capped or hollowed using various chemical methods.
For a more accurate spread for detection, nanoparticles can be deposited or spin-coated onto multiple surfaces.
Coating is metallic silver and Colloidal silver salts are popularly used in medicinal purposes and in medical devices.
Colloidal silver is a precious metal, used in jewelryand ornaments Other applications includeColloidal silver use in photography, electroplating, dentalalloys, high-capacity batteries, printed circuits,coins, and mirrors.
Colloidal silver is stable in air, and it is utilized in reflecting mirrors.
The film vacuum evaporated on a quartz plate with the thickness of 2–55 nm shows the transmittance maximum at λ: 321.5 nm and works as a narrow band filter.
The name Colloidal silver is derived from the Saxon word ‘siloflur’, which has been subsequently transformed into the German word ‘Silabar’ followed by ‘Silber’ and the English word ‘silver’.
Romans called the element ‘argentum’, and this is where the symbol Ag derives from.
Colloidal silver is widely distributed in nature.
Colloidal silver can be found in its native form and in various ores such as argentite (Ag2S), which is the most important ore mineral for silver, and horn silver (AgCl).
The principal sources of silver are copper, copper–nickel, gold, lead and lead–zinc ores, which can be mainly found in Peru, Mexico, China and Australia.
Colloidal silver and its alloys and compounds have numerous applications.
As a precious metal, Colloidal silver is used in jewelry.
Also, one of its alloys, sterling Colloidal silver, containing 92.5 weight % silver and 7.5 weight % copper, is a jewelry item and is used in tableware and decorative pieces.
The metal and Colloidal silver copper alloys are used in coins.
Colloidal silvers are widely recognized for their strong antimicrobial properties.
They are incorporated into products such as wound dressings, bandages, and medical devices to prevent bacterial and microbial growth.
In medical diagnostics, Colloidal silvers are explored for their use as contrast agents in imaging techniques such as magnetic resonance imaging (MRI).
Their unique properties contribute to enhanced imaging quality.
Colloidal silvers are investigated for drug delivery applications.
They can be designed to carry therapeutic agents and release them in a controlled manner, offering targeted drug delivery.
Colloidal silvers are integrated into textiles and clothing to provide antimicrobial and anti-odor properties.
This application is common in sportswear, undergarments, and fabrics used in healthcare settings.
Colloidal silvers are used in a variety of consumer products, including socks, kitchenware, and appliances, to impart antimicrobial properties and reduce the growth of bacteria that cause odors.
Colloidal silvers are employed in water treatment technologies to eliminate or reduce the presence of harmful microorganisms.
They can be part of filters, coatings, or solutions used for purifying water.
Due to their antimicrobial properties, Colloidal silvers are explored for use in food packaging materials.
They can help extend the shelf life of packaged foods by inhibiting the growth of microorganisms.
Colloidal silvers are used in the electronics industry to create conductive inks for printed electronics, flexible displays, and sensors.
Their electrical conductivity and compatibility with flexible substrates make them valuable in these applications.
Colloidal silvers exhibit catalytic activity and are employed in various catalytic reactions.
This has implications for applications in chemical synthesis and industrial processes.
In the medical field, Colloidal silvers are investigated for their use in photothermal therapy.
When exposed to specific wavelengths of light, they can generate heat, which may be utilized for targeted treatment of cancer cells.
Colloidal silvers may be included in certain cosmetic and personal care products for their potential antibacterial and preservative properties.
In the electronics industry, Colloidal silvers are used to create flexible and transparent conductive films, with applications in flexible electronics, touch screens, and electronic displays.
Colloidal silvers can exhibit photocatalytic activity, accelerating chemical reactions under light exposure.
This property is explored in applications like environmental remediation and water treatment.
Due to their antimicrobial properties, Colloidal silvers are employed in air purification systems to help eliminate or reduce the presence of harmful microorganisms.
Colloidal silvers find applications in various biomedical areas, including tissue engineering, biosensors, and the development of biocompatible materials.
Colloidal silvers are utilized in coatings for materials like glass and plastics to provide UV-blocking properties.
This is particularly important in products such as sunglasses, protective eyewear, and sunscreens.
In dentistry, Colloidal silvers are incorporated into dental materials such as composites and coatings to provide antimicrobial properties and reduce the risk of bacterial infections.
Colloidal silvers are being studied for potential applications in cancer treatment.
Their unique properties, including their ability to generate heat under light exposure, make them candidates for targeted cancer therapy.
Colloidal silvers are used in the production of transparent conductive films for solar cells.
These films enhance light absorption and electron transport within the solar cells, contributing to improved efficiency.
In electronics manufacturing, Colloidal silvers are employed in the fabrication of flexible printed circuit boards (FPCBs).
Their use supports the development of flexible and bendable electronic devices.
Colloidal silvers can be incorporated into coatings for eyewear and surfaces to provide anti-fog properties.
This is particularly beneficial in applications where clear visibility is essential.
Colloidal silvers are integrated into smart textiles, enabling the development of fabrics with electronic and sensing capabilities.
These textiles find applications in wearable technology and healthcare monitoring.
Colloidal silvers are studied for potential applications in the oil and gas industry, particularly in enhanced oil recovery processes and as additives in drilling fluids.
Colloidal silvers are used in packaging materials for electronic components to provide a conductive barrier and protect against environmental factors such as moisture and corrosion.
Colloidal silvers are utilized in the development of photonic devices, including sensors, waveguides, and components for optical communication systems.
Colloidal silvers are added to heat transfer fluids to enhance their thermal conductivity.
This is relevant in applications where efficient heat transfer is crucial, such as in cooling systems.
Colloidal silvers can be incorporated into 3D printing materials, allowing the production of conductive and functional 3D-printed objects for electronic and sensing applications.
Colloidal silvers are explored for their potential role in soil remediation, assisting in the removal of contaminants and pollutants from soil environments.
Colloidal silvers can be added to construction materials such as concrete to impart antimicrobial properties and reduce the growth of bacteria on surfaces.
Colloidal silver-copper brazing alloys and solders have many applications.
They are used in automotive radiators, heat exchangers, electrical contacts, steam tubes, coins, and musical instruments.
Some other uses of Colloidal silver metal include its applications as electrodes, catalysts, mirrors, and dental amalgam.
Colloidal silver is used as a catalyst in oxidation-reductions involving conversions of alcohol to aldehydes, ethylene to ethylene oxide, and ethylene glycol to glyoxal.
Colloidal silver has a multitude of uses and practical applications both in Colloidal silver elemental metallic formand as a part of its many compounds.
Colloidal silver is excellent electrical conductivity makes it ideal for usein electronic products, such a computer components and high-quality electronic equipment.
Colloidal silver would be an ideal metal for forming the wiring in homes and transmission lines, if Colloidal silver weremore abundant and less expensive.
Metallic Colloidal silver has been used for centuries as a coinage metal in many countries.
Theamount of silver now used to make coins in the United States has been reduced drastically byalloying other metals such as copper, zinc, and nickel with Colloidal silver.
Colloidal silver is used as a catalyst to speed up chemical reactions, in water purification, and inspecial high-performance batteries (cells).
Colloidal silver is high reflectivity makes it ideal as a reflectivecoating for mirrors.
Production Methods of Colloidal silver:
Many processes are known for recovery of Colloidal silver from its ores.
These depend mostly on the nature of the mineral, its silver content, and recovery of other metals present in the ore.
Colloidal silver is usually extracted from high-grade ores by three common processes that have been known for many years.
These are amalgamation, leaching, and cyanidation.
In one amalgamation process, ore is crushed and mixed with sodium chloride, copper sulfate, sulfuric acid, and mercury, and roasted in cast iron pots.
The amalgam is separated and washed.
Silver is separated from Colloidal silver amalgam by distillation of mercury.
In the cyanidation process the ore is crushed and roasted with sodium chloride and then treated with a solution of sodium cyanide.
Colloidal silver forms a stable Colloidal silver cyanide complex, [Ag(CN)2]–.
Adding metallic zinc to this complex solution precipitates Colloidal silver.
One such process, known as the Patera process, developed in the mid 19th century, involves roasting ore with sodium chloride followed by leaching with sodium thiosulfate solution.
Colloidal silver 834 SILVERis precipitated as silver sulfide, Ag2S, by adding sodium sulfide to the leachate.
In the Clandot process, leaching is done with ferric chloride solution.
Addition of zinc iodide precipitates Colloidal silver iodide, AgI.
AgI is reduced with zinc to obtain Colloidal silver.
The above processes are applied for extraction of Colloidal silver from high-grade ores.
However, with depletion of these ores, many processes were developed subsequently to extract Colloidal silver from low-grade ores, especially lead, copper, and zinc ores that contain very small quantities of silver.
Low grade ores are concentrated by floatation.
The concentrates are fed into smelters (copper, lead, and zinc smelters).
The concentrates are subjected to various treatments before and after smelting including sintering, calcination, and leaching.
Copper concentrates are calcined for removal of sulfur and smelted in a reverberatory furnace to convert into blister copper containing 99 wt% Cu.
The blister copper is fire-refined and cast into anodes.
The anodes are electrolytically refined in the presence of cathodes containing 99.9% copper.
Insoluble anode sludges from electrolytic refining contain silver, gold, and platinum metals.
Colloidal silver is recovered from the mud by treatment with sulfuric acid.
Base metals dissolve in sulfuric acid leaving Colloidal silver mixed with any gold present in the mud.
Colloidal silver is separated from gold by electrolysis.
Lead and zinc concentrates can be treated in more or less the same manner as copper concentrates.
Sintering lead concentrates removes sulfur and following that smelting with coke and flux in a blast furnace forms impure lead bullion.
The lead bullion is drossed with air and sulfur and softened with molten bullion in the presence of air to remove most impurities other than Colloidal silver and gold.
Copper is recovered from the dross and zinc converts to Colloidal silver oxide and is recovered from blast furnace slag.
The softened lead obtained above also contains some Colloidal silver.
The Colloidal silver is recovered by the Parkes Process.
The Parkes process involves adding zinc to molten lead to dissolve Colloidal silver at temperatures above the melting point of zinc.
On cooling, zinc-silver alloy solidifies, separating from the lead and rising to the top.
The alloy is lifted off and zinc is separated from silver by distillation leaving behind metallic Colloidal silver.
The unsoftened lead obtained after the softening operation contains Colloidal silver in small but significant quantities.
Such unsoftened lead is cast into anode and subjected to electrolytic refining.
The anode mud that is formed adhering to these anodes is removed by scraping.
Colloidal silver contains bismuth, silver, gold, and other impurity metals.
Colloidal silver is obtained from this anode mud by methods similar to the extraction of anode mud from the copper refining process discussed earlier.
If the low–grade ore is a zinc mineral, then zinc concentrate obtained from the flotation process is calcined and leached with water to remove zinc.
Colloidal silver and lead are left in leach residues.
Residues are treated like lead concentrates and fed into lead smelters.
Colloidal silver is recovered from this lead concentrate by various processes described above.
Environmental Fate of Colloidal silver:
Colloidal silver exists in four oxidation states (0,+1,+2,and +3).
Colloidal silver occurs primarily as sulfides with iron, lead, tellurides, and with gold.
Colloidal silver is a rare element, which occurs naturally in its pure form.
Colloidal silver is a white, lustrous, relatively soft, and very malleable metal.
Colloidal silver has an average abundance of about 0.1 ppm in the Earth’s crust and about 0.3 ppm in soils.
History of Colloidal silver:
Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate Colloidal silver from lead as early as 3000 B.C.
Colloidal silver occurs native and in ores such as argentite (Ag2S) and horn silver (AgCl); lead, lead-zinc, copper, gold, and copper-nickel ores are principal sources.
Mexico, Canada, Peru, and the U.S. are the principal Colloidal silver producers in the western hemisphere.
Colloidal silver is also recovered during electrolytic refining of copper.
Commercial fine silver contains at least 99.9% silver.
Purities of 99.999+% are available commercially.
Pure silver has a brilliant white metallic luster.
Colloidal silver is a little harder than gold and is very ductile and malleable, being exceeded only by gold and perhaps palladium.
Pure Colloidal silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance.
Colloidal silver is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulfide, or air containing sulfur.
The alloys of Colloidal silver are important.
Sterling Colloidal silver is used for jewelry, silverware, etc. where appearance is paramount.
This alloy contains 92.5% silver, the remainder being copper or some other metal.
Colloidal silver is of utmost importance in photography, about 30% of the U.S. industrial consumption going into this application.
Colloidal silver is used for dental alloys.
Colloidal silver is used in making solder and brazing alloys, electrical contacts, and high capacity silver–zinc and silver–cadmium batteries.
Colloidal silver paints are used for making printed circuits.
Colloidal silver is used in mirror production and may be deposited on glass or metals by chemical deposition, electrodeposition, or by evaporation.
When freshly deposited, Colloidal silver is the best reflector of visible light known, but is rapidly tarnishes and loses much of Colloidal silver reflectance.
Colloidal silver is a poor reflector of ultraviolet.
Colloidal silver fulminate (Ag2C2N2O2), a powerful explosive, is sometimes formed during the silvering process.
Colloidal silver iodide is used in seeding clouds to produce rain.
Colloidal silver chloride has interesting optical properties as Colloidal silver can be made transparent.
Colloidal silver also is a cement for glass.
Colloidal silver nitrate, or lunar caustic, the most important silver compound, is used extensively in photography.
While Colloidal silver itself is not considered to be toxic, most of its salts are poisonous.
Natural silver contains two stable isotopes.
Fifty-six other radioactive isotopes and isomers are known.
Colloidal silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body.
A condition, known as argyria, results with a greyish pigmentation of the skin and mucous membranes.
Colloidal silver has germicidal effects and kills many lower organisms effectively without harm to higher animals.
Colloidal silver for centuries has been used traditionally for coinage by many countries of the world.
In recent times, however, consumption of Colloidal silver has at times greatly exceeded the output.
In 1939, the price of silver was fixed by the U.S. Treasury at 71￠/troy oz., and at 90.5￠/troy oz. in 1946.
In November 1961 the U.S. Treasury suspended sales of nonmonetized Colloidal silver, and the price stabilized for a time at about $1.29, the melt-down value of silver U.S. coins.
The Coinage Act of 1965 authorized a change in the metallic composition of the three U.S. subsidiary denominations to clad or composite type coins.
This was the first change in U.S. coinage since the monetary system was established in 1792.
Clad dimes and quarters are made of an outer layer of 75% Cu and 25% Ni bonded to a central core of pure Cu.
The composition of the oneand five-cent pieces remains unchanged.
One-cent coins are 95% Cu and 5% Zn.
Earlier subsidiary coins of 90% Ag and 10% Cu officially were to circulate alongside the clad coins; however, in practice they have largely disappeared (Gresham’s Law), as the value of the silver is now greater than their exchange value.
Colloidal silver coins of other countries have largely been replaced with coins made of other metals.
On June 24, 1968, the U.S. Government ceased to redeem U.S. Silver Certificates with silver.
The price of Colloidal silver in 2001 was only about four times the cost of the metal about 150 years ago.
This has largely been caused by Central Banks disposing of some of their silver reserves and the development of more productive mines with better refining methods.
Also, Colloidal silver has been displaced by other metals or processes, such as digital photography.
Safety Profile of Colloidal silver:
Human systemic effects by inhalation: skin effects.
The acute toxicity of silver metal is low.
The acute toxicity of soluble silver compounds depends on the counterion and must be evaluated case by case.
For example, silver nitrate is strongly corrosive and can cause burns and permanent damage to the eyes and skin.
Chronic exposure to silver or silver salts can cause a local or generalized darkening of the mucous membranes, skin, and eyes known as argyria.
The other chronic effects of silver compounds must be evaluated individually.
Although Colloidal silvers are widely used in a variety of commercial products, there has only recently been a major effort to study their effects on human health.
Inhalation of dusts can cause argyrosis.
Questionable carcinogen with experimental tumorigenic data.
Flammable in the form of dust when exposed to flame or by chemical reaction with C2H2, NH3, bromoazide, ClF3 ethyleneimine, H2O2, oxalic acid, H2SO4, tartaric acid.
Incompatible with acetylene, acetylene compounds, aziridine, bromine azide, 3-bromopropyne, carboxylic acids, copper + ethylene glycol, electrolytes + zinc, ethanol + nitric acid, ethylene oxide, ethyl hydroperoxide, ethyleneimine, iodoform, nitric acid, ozonides, peroxomonosulfuric acid, peroxyformic acid.
Properties of Colloidal silver:
Melting point: 960 °C(lit.)
Boiling point: 2212 °C(lit.)
Density: 1.135 g/mL at 25 °C
vapor density: 5.8 (vs air)
vapor pressure: 0.05 ( 20 °C)
refractive index: n20/D 1.333
Flash point: 232 °F
storage temp.: 2-8°C
solubility: H2O: soluble
form: wool
color: Yellow
Specific Gravity: 10.49
Odor: Odorless
Resistivity: 1-3 * 10^-5 Ω-cm (conductive paste) &_& 1.59 μΩ-cm, 20°C
Water Solubility: insoluble
Sensitive: Light Sensitive
Merck: 13,8577