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Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Silver (Ag), a precious metal, has an atomic number of 47, an atomic weight of 107.868, and a density of 10.50 g cm–3. Many lead, zinc, and copper ores are argentiferous, that is, these contain argentite or silver sulfide (Ag2S). Silver is extracted as a by-product from the mining of these three metals. However, being a precious metal, even small amounts of silver fetch a lucrative price. Silver is also an essential constituent of calaverite, which is a gold telluride [(AuAg)Te2]. Silver, alloyed with copper to make it hard, is used for making cutlery, utensils, coins, ornaments, and jewelry. Among the other uses of silver, silver vats are used during the production of acetic acid, vinegar, and cider, because of the resistant nature of silver to acetic acid. It is also used in silver solders, dental amalgams, batteries, ceramic paints, and other items. Silver also acts as a catalyst in the synthesis of formaldehyde and acetaldehyde. The property of silver halides of reacting to light instantaneously makes them invaluable in the production of films, plates, and photographic printing paper. Silver nitrate (AgNO3) is an important laboratory reagent in analytical chemistry, and is used for making mirrors, photography, silver plating, dyeing, and numerous other uses ranging from indelible inks and water disinfectant to antiseptic ointments and astringents (Encyclopaedia of Occupational Health and Safety 2012). Silver has very strong antimicrobial properties, and nanosilver compounds are expected to revolutionize the use of silver in antimicrobial formulations.
Light-Sensitive Materials: Silver Halide Emulsions, Photoresist, and Photopolymers
Published in Daniel Malacara-Hernández, Brian J. Thompson, Advanced Optical Instruments and Techniques, 2017
Sergio Calixto, Daniel J. Lougnot, Izabela Naydenova
The silver halide photographic emulsion [6] consists of several materials, such as the silver halide crystals, a protective colloid, and a small amount of compounds, such as sensitizers and stabilizers. Usually, this emulsion is coated on some suitable support that can be a sheet of transparent plastic (e.g., acetate) or over glass plates, depending on the application. In the photographic emulsion, the silver halide crystals could consist of any one of silver chloride (AgCl), silver bromide (AgBr), or silver iodide (AgI). Silver halide emulsions can contain one class of crystals or mixed crystals, such as AgCl + AgBr or AgBr + AgI. Sensitivity of emulsions depends on the mixing ratio. The protective colloid is the second most important component in the emulsion. It supports and interacts with the silver halide grains. During the developing process, it allows processing chemicals to penetrate, and eases the selective development of exposed grains. Different colloids have been used for the fabrication of photographic films; however, gelatin seems the most favorable material for emulsion making.
Digital Still Cameras at a Glance
Published in Junichi Nakamura, Image Sensors and Signal Processing for Digital Still Cameras, 2017
At first, digital still cameras were used for printing flyers or information magazines for used cars. The pictures that they use are relatively small and do not require very high resolution; they benefit greatly from the instant availability of pictures that digital cameras provide. They became popular among commercial photographers who take pictures for ordinary brochures, catalogues, or magazines because the picture quality grew higher. Many photographers nowadays are beginning to use digital still cameras in place of silver halide cameras.
Hierarchical ZnO nanostructure flowers loaded with AgI nanoparticles for photodegradation of methylene blue under UV visible radiation
Published in Inorganic and Nano-Metal Chemistry, 2022
Prakasit Intaphong, Anukorn Phuruangrat, Kamran Akhbari, Thawatchai Sakhon, Titipun Thongtem, Somchai Thongtem
Silver halides such as AgI, AgBr, and AgCl are popular in the photocatalytic process because they are strong visible-light photosensitive materials.[1,9,10] AgI as p-type semiconductor with band-gap of 2.8 eV shows excellent visible-light-driven photocatalytic activity for photodegradation of organic dye pollutants in wastewater because AgI has appropriate conduction and valence band edges at −0.40 eV and +2.36 eV vs NHE and has high rate of electron–hole separation.[1,9–11]
Dry gelatin ‘Photo-mechanical’ plates – their significance in the evolution of scientific & technical photography
Published in The Imaging Science Journal, 2023
Photographic recording materials of this (and later) era were based on the light sensitivity of silver salts (silver halides). These were in the form of micrometre scale particles dispersed in binders which also fulfilled the function of adhering the particles in a thin layer onto a glass plate. For those not familiar with these technologies this section provides a basic introduction with suggestions for some standard reference works that will give more detail.