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Eco-Friendly Synthesis of Metal Nanoparticles for Smart Nanodevices in the Treatment of Diseases
Published in Suvardhan Kanchi, Rajasekhar Chokkareddy, Mashallah Rezakazemi, Smart Nanodevices for Point-of-Care Applications, 2022
Gold is a chemical element with the symbol Au. It is a precious metal used mostly for jewelry, coinage and other artwork [38]. Among the successful development of metal nanoparticles, AuNP explored various nanotechnology-related biomedical applications, and also has non-toxic [39], unique optical, physicochemical and biological properties [40]. Applications include tumor destruction [41], environmental, health care, gene delivery, optics, food industry and space industry [42]. In the 19th century, it has been used as an “anxiolytic” therapy for nervous disorders [43]. And recently, many reports have stated that it can cross the BBB, may interact with DNA and produce genotoxic effects [44].
Environmental Impact of Gold Mining
Published in Mritunjoy Sengupta, Environmental Impacts of Mining, 2021
Modern industrial gold mining destroys landscapes and creates huge quantities of toxic wastes. Due to the use of dirty practices such as open-pit mining and cyanide heap leach mining, companies generate about 20 tons of toxic substances for every 0.333-ounce of a gold ring. The waste, usually a grey liquid, is laden with cyanide and toxic heavy metals.
Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
Symbols and names of elements are derived from a number of sources. They may have been named after the person who discovered the element. For example, W which is the symbol for tungsten is named after Wolfram, the discoverer. Other elements are named after famous scientists, universities, cities and states. Es is the symbol for einsteinium, named after Albert Einstein. Cm is the symbol for curium, named after Madam Curie. Bk is the symbol for berkelium, named after the city of Berkeley, California. Cf is the symbol for the element californium, named after the state of California. Other element names come from Latin, German, Greek and English languages. In the case of sodium, Na comes from the Latin word for natrium. Au, the symbol for gold, comes from aurum, meaning “shining down” in Latin. Cu (copper) comes from the Latin cuprum or cyprium because the Roman source for copper was the island of Cyprus. Fe (iron) comes from the Latin ferrum. Bromine means “stinch” in Greek. Rubidium means red in color. Mercury is sometimes referred to as quick silver. Sulfur is referred to as brimstone in the Bible.
Morphological characterization of lode gold in the auriferous quartz veins at M’Popo mine, Angola, by computed tomography and optical microscopy
Published in Applied Earth Science, 2023
Stephanie Lohmeier, Ramil R. Gainov, Andrew Hodgkin
The most conspicuous mineral in all samples is gold of a uniform deep yellow colour, which is attributed to the average low silver content in the gold grains of 5% (Sevillano et al. 2011). Gold occurs from as small as sub-microscopic particles of <<10 µm to a few 100 µm in size through to large gold grains up to almost 20 mm³ in the samples studied. The gold particles may sit in voids of pyrite crystals, but occurs mostly along pyrite grain borders; to a lesser extent, they are also as native mineral in quartz gangue (Figure 6). Thus, the bulk of gold can be assumed to be free gold: if any gold at all occurs in the pyrite crystal lattice, it must be minor. Gold is post-sulfide and has in 2D microscopy a subrounded to dendrite-like shape. Gold has a density of ∼19.3 g cm−³ and is thus the mineral with the clearly highest density present.
Gold extraction from biosolid sludge obtained by sewage treatment
Published in Environmental Technology, 2019
Sara AlKetbi, Hussain Elsayed, Sulaiman Al-Zuhair
Gold is a precious metal, which if found among the heavy metals extracted from the biosolids would make the treatment process more advantageous. A survey of metal concentrations found in the sludge treated in the biosolid treatment facilities of Texas indicated the presence of gold in the biosolids [24]. Gold extraction by potassium cyanide solution is an old method, which is used at a large scale for extracting gold from its ores. After extraction, the extracted gold is precipitated using zinc shavings. Potassium cyanide has a high extraction selectivity for gold, allowing only gold to be extracted leaving behind other metals. However, this technique is not suitable for heavy metal extraction from biomass meant to be used as a fertilizer, because it is more desirable to extract all heavy metals and not only gold. In addition, cyanide is highly poisonous and harmful to the environment. Thiourea has been suggested as an alternative safer solvent [25]. A solution containing 24 g/L of thiourea and 0.6% of Fe3+ was found to be effective, and within 2 h, over 90% of gold was extracted from mobile phone scraps. However, the main disadvantages of this technique are the high cost of the oxidant (ferric ion) and the need for large volumes of reagents [26].
A Comparative Study on the Extraction of Au(III) Using Cyclopentyl Methyl Ether, Dibutyl Carbitol, and Methyl Isobutyl Ketone in Acidic Chloride Media
Published in Solvent Extraction and Ion Exchange, 2021
Tatsuya Oshima, Takao Koyama, A. Noriyasu Otsuki
Besides its use in jewelry and decorations, gold has also been used in electronic devices because of its high electrical conductivity and corrosion resistance.[,12] Along with the increase in global gold consumption, gold recovery from the discarded electronic devices has been recognized as an important issue.[3–7] Waste electrical and electronic equipment (WEEE) that contains gold is pretreated by processes that involve washing, crushing, separation, and incineration, depending on the nature of the scrap.[1] Pyrometallurgical or hydrometallurgical processes are followed by pretreatment for the purification of precious-metal-containing gold.