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List of Chemical Substances
Published in T.S.S. Dikshith, and Safety, 2016
Arsenate minerals are minerals containing the arsenate (AsO43-) anion group—arsenic acid, calcium arsenate, chromated copper arsenate, copper(II) arsenate, lead hydrogen arsenate, monosodium methyl arsenate, potassium arsenate, arsenates, arsenic minerals, arsenical herbicides, arsenides, and arsenites. Arsenate resembles phosphate in many respects, since arsenic and phosphorus occur in the same group.
Removal of As(III) and As(V) from water using reduced GO-Fe0 filled PANI composite
Published in Journal of Applied Water Engineering and Research, 2022
Shreemoyee Bordoloi, Rupkamal Chetia, Geetika Borah, Surajit Konwer
Contamination of water from carcinogenic metalloid arsenic is creating a menace worldwide as a long time exposure to arsenic through drinking water can cause severe health problems (Thomas et al. 2007; Chakraborti et al. 2010). Chronic exposure to arsenic-contaminated drinking water is the major cause of arsenic poisoning in developing countries, such as, India (Chakraborti et al. 2002), Bangladesh (Roberts et al. 2011), China (Xie et al. 2009), Vietnam (Kim et al. 2009), where millions of people are using arsenic-contaminated groundwater with concentration above WHO guideline of 10 µg/L for arsenic (WHO, Environmental Health Criteria 224 2001; Berg et al. 2006). Arsenic is released into water sources by natural processes, such as dissolution and weathering of arsenic minerals or by some anthropogenic activities such as mining, use of arsenical pesticides, herbicides, fertilizers in agriculture, industrial effluents, improper disposal of chemical waste etc. Arsenate, As(V) (H3AsO4, , ) along with arsenite, As(III) (H3AsO3, , ), is the primary inorganic form in groundwater (Nickson et al. 2000). Greater attention is required for the removal of As(III) from groundwater due to its higher toxicity and mobility than As(V).
Removal of arsenic from gold processing circuits by use of novel magnetic nanoparticles
Published in Canadian Metallurgical Quarterly, 2018
C. Feng, C. Aldrich, J. J. Eksteen, D. W. M. Arrigan
Arsenic is notoriously known as a highly toxic element present in the crust of the earth, directly or indirectly threatening human health and nature [1]. Generally speaking, the most common arsenic minerals associated with the gold mining industry are sulphides, such as arsenopyrite (FeAsS), enargite (Cu3AsS4) and tennantite ((Cu,Fe)12As4S13). The presence of arsenic has caused a lot of problems not only for the mining of gold ores but also for the extraction of gold. For instance, under the alkaline conditions of gold leaching by cyanidation, arsenic sulphides can be oxidised to arsenite (AsO33−) and arsenate (AsO43−) and partially oxidised to thioarsenite (AsS33−) and thioarsenate (AsS43−), leading to increased oxygen consumption, which could adversely influence the cyanidation process by impeding gold dissolution [2]. Moreover, free cyanide ions might participate in further oxidation of thioarsenites and thioarsenates to form thiocyanates, causing undesired consumption of lixiviant [3]. Meanwhile, these oxidised species tend to attach to the gold surface thus hindering the interaction of gold with cyanide ions and oxygen. Additionally, arsenic may also affect the gold recovery process via competitive adsorption onto activated carbon [4]. Last but not the least, arsenic entering the tailings dams can raise issues. A few studies have indicated that the more toxic As(III) species are more soluble than As(V) species in tailings waters [5–7], making the subsequent treatment difficult and complicated.
Field-scale bioremediation of arsenic-contaminated groundwater using sulfate-reducing bacteria and biogenic pyrite
Published in Bioremediation Journal, 2018
Ming-Kuo Lee, James A. Saunders, Theodore Wilson, Eric Levitt, Shahrzad Saffari Ghandehari, Prakash Dhakal, James Redwine, Justin Marks, Zeki M. Billor, Brian Miller, Dong Han, Luxin Wang
The geochemistry and mineralogy of arsenic are generally well established (Lowers et al. 2007; Smedley and Kinniburgh 2002; Nordstrom 2002; Nordstrom and Archer; O’Day et al. 2004), with the possible exception of what are the stable arsenic-bearing solid phases expected in low-temperature environments. Dissolved arsenic occurs in two oxidation states in most natural waters. Under oxidizing conditions, pentavalent arsenate [As(V)] species (H2AsO4−, HAsO42−, and AsO43−) are dominant. Under moderately reducing conditions, trivalent arsenite [As(III)] species H3AsO3 predominates over a wide range of pH values (Figure 1). Under even more reducing conditions, solid arsenic sulfides or thioarsenite aqueous complexes may become the dominant phases in sulfur-rich environments (Lee et al. 2005; Saunders et al. 2008) (Figure 1). Orpiment (As2S3), realgar (AsS), and arsenopyrite (FeAsS) are the most commonly occurring arsenic minerals under reducing hydrothermal conditions in nature, although metal-arsenide minerals do occur rarely. Under highly reducing conditions, As-bearing pyrite appears to control arsenic solubility in reducing environments containing reactive iron and sulfur (Saunders et al. 2008) (see the section “Results and Discussion”). The geochemistry of arsenic has received new interest and research due to the worldwide problem of arsenic contamination (natural and anthropogenic) of potable drinking water supplies (Smedley and Kinniburgh 2002; Nordstrom and Archer 2003; O’Day 2006; Nordstrom et al. 2014; McArthur et al. 2004).