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Heavy Metals
Published in Abhik Gupta, Heavy Metal and Metalloid Contamination of Surface and Underground Water, 2020
Arsenic (As) has an atomic number of 33, an atomic weight of 74.922, and a density of 5.72 g cm–3. Arsenopyrite or iron-arsenic sulfide (FeAsS2) is the most common ore of arsenic. Realgar (As4S4) and orpiment (As2S3) are important ores of As as well. Arsenic can occur as inorganic arsenic compounds, which in turn can have the trivalent or pentavalent form of the element. Besides, arsenic also occurs as organic arsenic compounds, and as arsine gas and substituted arsines. The addition of elemental arsenic to alloys increases their hardness and heat resistance. Elemental arsenic is also used in some types of glass, and in electrical devices. Arsenic trichloride (AsCl3) is used to make pharmaceuticals, pesticides, and ceramics. Arsenic trioxide (As2O3) is the precursor to other arsenic compounds, and is used as a hide and wood preservative, a mordant, and decolorizing agent in glass manufacture. Some arsenic compounds are also used as insecticides, herbicides, corrosion inhibitors, and dehairing agents in the tanning industry. Pentavalent arsenic compounds are used in glass-making, wood-curing, and as herbicides, insecticides, and wood preservatives. Organic arsenic compounds are also used as herbicides and defoliants (Encyclopaedia of Occupational Health and Safety 2012).
The Fate of the Arsenic Species in the Pressure Oxidation of Refractory Gold Ores: Practical and Modelling Aspects
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Wei Sung Ng, Yanhua Liu, Qiankun Wang, Miao Chen
Arsenic is not expected to be present as any major gaseous products under the conditions of pressure oxidation. While arsenic may potentially be present in the gas phase as arsenic trioxide (As2O3), the volatilization temperature of As2O3 is above 450°C, much higher than the normal operating conditions in the autoclave. At high chloride concentrations and in the presence of hydrochloric acid, it may be possible for arsenic trichloride (AsCl3) to be present in the autoclave via reaction of the As2O3 in solution. The volatilization temperature of AsCl3 is much lower at 130°C, and formation is likely to be followed by rapid boiling into the gas phase. Arsenic in the gas phase is more prevalent in processes such as roasting, where arsenic is volatilized via the high thermal conditions, and treatment of the off-gas is required to ensure safe disposal of the arsenic.
A comparative study on subacute toxicity of arsenic trioxide and dimethylarsinic acid on antioxidant status in Crandell Rees feline kidney (CRFK), human hepatocellular carcinoma (PLC/PRF/5), and epithelioma papulosum cyprini (EPC) cell lines
Published in Journal of Toxicology and Environmental Health, Part A, 2018
Antonia Concetta Elia, Gabriele Magara, Claudio Caruso, Loretta Masoero, Marino Prearo, Paola Arsieni, Barbara Caldaroni, Ambrosius Josef Martin Dörr, Melissa Scoparo, Stefania Salvati, Paola Brizio, Stefania Squadrone, Maria Cesarina Abete
Arsenic, mainly the inorganic species, is highly toxic to living organisms; it may directly bind to protein–sulphydryl (SH) groups or increase cellular ROS production (Flora et al. 2005; Maheshwari, Khan, and Mahmood 2017). Proteins with potential of high thiol-disulfide oxidation may be redox sensitive, mediating both the toxic and the therapeutic effects of As. Arsenic is present in four oxidation states—arsenate (+5), arsenite (+3), elemental arsenic (0), and arsine (−3)—and in both inorganic and organic forms. There are two species of inorganic arsenic: trivalent arsenic iAsIII (e.g., sodium arsenite, arsenic trioxide, and arsenic trichloride) and pentavalent arsenic iAsV (e.g., arsenates). Both AsIII and AsV use different pathways to move in the animals and human cells; AsIII is structurally similar to glycerol and may be transported through aquaporins, whereas AsV is similar to phosphate and may enter cells via phosphate transporters (Sun et al. 2014). Arsenic toxicity is related to its chemical speciation; arsenite (AsIII) is more toxic than arsenate (Koehler et al. 2014). Arsenite may react with sulfhydryl groups, inducing structural modification in protein and enzyme inactivation, whereas arsenate might impair ATP synthesis via arsenolysis process (Ventura-Lima, Reis Bogo, and Monserrat 2011).