Journal articles: 'Arsenic – Oxidation'

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Sorlini, S., F. Gialdini, and M. Stefan. "Arsenic oxidation by UV radiation combined with hydrogen peroxide." Water Science and Technology 61, no. 2 (January 1, 2010): 339–44. http://dx.doi.org/10.2166/wst.2010.799.

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Arsenic is a widespread contaminant in the environment around the world. The most abundant species of arsenic in groundwater are arsenite [As(III)] and arsenate [As(V)]. Several arsenic removal processes can reach good removal yields only if arsenic is present as As(V). For this reason it is often necessary to proceed with a preliminary oxidation of As(III) to As(V) prior to the removal technology. Several studies have focused on arsenic oxidation with conventional reagents and advanced oxidation processes. In the present study the arsenic oxidation was evaluated using hydrogen peroxide, UV radiation and their combination in distilled and in real groundwater samples. Hydrogen peroxide and UV radiation alone are not effective at the arsenic oxidation. Good arsenic oxidation yields can be reached in presence of hydrogen peroxide combined with a high UV radiation dose (2,000 mJ/cm2). The quantum efficiencies for As(III) oxidation were calculated for both the UV photolysis and the UV/H2O2 processes.

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Kato, Tatsuya, Yohei Kawasaki, Masakazu Kadokura, Kohei Suzuki, Yasuhiro Tawara, Yoshiyuki Ohara, and Chiharu Tokoro. "Application of GETFLOWS Coupled with Chemical Reactions to Arsenic Removal through Ferrihydrite Coprecipitation in an Artificial Wetland of a Japanese Closed Mine." Minerals 10, no. 5 (May 23, 2020): 475. http://dx.doi.org/10.3390/min10050475.

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Passive systems that utilize a natural power such as a pond, plant, or microorganisms, is expected to be a cost-effective method for acid mine drainage (AMD) treatment. The Ningyo-toge mine, a non-operational uranium mine located in Okayama Prefecture, Japan, generates AMD containing arsenic and iron. To quantitatively study arsenic and iron ion removal in an artificial wetland and pond, chemical reactions were modeled and incorporated into the GETFLOWS (general-purpose terrestrial fluid-flow simulator) software. The chemical reaction models consisted of arsenite and ferrous oxidation equations and arsenic adsorption on ferrihydrite. The X-ray diffraction analysis of sediment samples showed ferrihydrite patterns. These results were consistent with the model for arsenite/ferrous oxidation and arsenic adsorption on ferrihydrite. Geofluid simulation was conducted to simulate mass transfer with the utilized topographic model, inlet flow rate, precipitation, and evaporation. The measured arsenic and iron ions concentrations in solution samples from the wetland and pond, fitted well with the model. This indicated that the main removal mechanism was the oxidation of arsenite/ferrous ions and that arsenic was removed by adsorption rather than dilution.

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Spaziani, Fabio, Yuli Natori, Yoshiaki Kinase, Tomohiko Kawakami, and Katsuyoshi Tatenuma. "Elementary Iodine-Doped Activated Carbon as an Oxidizing Agent for the Treatment of Arsenic-Enriched Drinking Water." Water 11, no. 9 (August 27, 2019): 1778. http://dx.doi.org/10.3390/w11091778.

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An activated carbon impregnated with elementary iodine (I2), named IodAC, characterized by oxidation capability, was developed and applied to oxidize arsenite, As(III), to arsenate, As(V), in arsenic-rich waters. Batch and column experiments were conducted to test the oxidation ability of the material. Comparisons with the oxidizing agents usually used in arsenic treatment systems were also conducted. In addition, the material has been tested coupled with an iron-based arsenic sorbent, in order to verify its suitability for the dearsenication of drinking waters. IodAC exhibited a high and lasting oxidation potential, since the column tests executed on water spiked with 50 mg/L of arsenic (100% arsenite) showed that 1 cc of IodAC (30 wt% I2) can oxidize about 25 mg of As(III) (0.33 mmol) before showing a dwindling in the oxidation ability. Moreover, an improvement of the arsenic sorption capability of the tested sorbent was also proved. The results confirmed that IodAC is suitable for implementation in water dearsenication plants, in place of the commonly used oxidizing agents, such as sodium hypochlorite or potassium permanganate, and in association with arsenic sorbents. In addition, the well-known antibacterial ability of iodine makes IodAC particularly suitable in areas (such developing countries) where the sanitation of water is a critical topic.

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Song, Wei Feng, Qi Deng, Li Ying Bin, Wei Wang, and Chun Wu. "Arsenite Oxidation Characteristics and Molecular Identification of Arsenic-Oxidizing Bacteria Isolated from Soil." Applied Mechanics and Materials 188 (June 2012): 313–18. http://dx.doi.org/10.4028/www.scientific.net/amm.188.313.

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Arsenite oxidation characteristics were studied through domesticated bacteria from soil added arsenic artificially, which came from Dinghu Mountain Natural Reserve of Zhaoqing, Guangdong, China. Two individual bacterial strains were selected as arsenite-oxidizing bacteria by reaction of silver nitrate and detected in community DNA fingerprints generated by PCR coupled with denaturing gradient gel electrophoresis. Physiological, biochemical and arsenite oxidation characteristics of arsenic-oxidizing bacteria were researched. They were gram-negative and rod-shaped bacteria, which were 99% related to Alcaligenes sp.(strain H) and 100% related to Agrobacterium sp. (strain Q) respectively. The arsenic-oxidizing experiment showed that the optimal temperature and pH were 30°Cand 9.0 respectively for both strains. Strain H was an efficient arsenite-oxidizing bacteria. It oxidized As(III) by nearly 100% after 21 hours. Therefore, It was detected as the most perspective strains in this study.

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Rowland, H. A. L., A. G. Gault, J. M. Charnock, and D. A. Polya. "Preservation and XANES determination of the oxidation state of solid-phase arsenic in shallow sedimentary aquifers in Bengal and Cambodia." Mineralogical Magazine 69, no. 5 (October 2005): 825–39. http://dx.doi.org/10.1180/0026461056950291.

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AbstractDetermination of the solid-phase arsenic speciation in sediments hosting high-arsenic groundwaters, utilized for drinking and irrigation in Bengal, SE Asia and elsewhere is important in order to understand the biogeochemistry of arsenic. Despite this, there is a relative paucity of speciation data for solid-phase arsenic in such systems, due to preservation difficulties, low arsenic concentrations in the sediments, multiple coordination environments and sample heterogeneity. In this study, X-ray absorption near edge structure spectroscopy was used in conjunction with linear least-squares fitting of model compounds to determine the oxidation state of arsenic in sediments from West Bengal and Cambodia. Whatever the collection and storage method used, substantial oxidation of arsenic was commonly observed over periods of weeks to several months. Sands were particularly susceptible to changes in arsenic oxidation state during storage. Analysis within two or three weeks of collection is therefore recommended, whilst on-site storage under a nitrogen atmosphere immediately after collection is particularly recommended for the preservation of sandy samples. Both muds and sands from West Bengal and Cambodia were dominated by arsenite (As(III)) with <35±10% arsenate (As(V)). Complete oxidation to arsenate was never observed suggesting that a significant proportion of the sedimentary arsenic is inaccessible within crystalline phases. Centrifuging under anaerobic conditions enabled more detailed information about a variety of arsenic coordination environments to be determined.

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Ai, L. Nguyen, A. Sato, D. Inoue, K. Sei, S. Soda, and M. Ike. "Enrichment of arsenite oxidizing bacteria under autotrophic conditions and the isolation and characterization of facultative chemolithoautotrophic arsenite oxidizing bacteria for removal of arsenic from groundwater." Water Supply 12, no. 5 (August 1, 2012): 707–14. http://dx.doi.org/10.2166/ws.2012.045.

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Arsenic contamination in groundwater has caused severe health problems throughout the world. Developing cost-effective processes for arsenic removal is an emerging issue. Because As(III) is predominant in groundwater and is more difficult to remove than As(V) is, oxidation of As(III) to As(V) is necessary to improve overall arsenic removal. This study was undertaken to enrich arsenite oxidizing bacteria under autotrophic conditions and to isolate and characterize facultative chemolithoautotrophic arsenite oxidizing bacteria (CAOs) that can oxidize As(III) effectively to As(V). An enrichment culture which adapted wide As(III) concentrations and completely oxidized 12 mM As(III) within 4 days under autotrophic conditions was established and maintained. Among 10 isolated strains, 6 strains, B1, B2, C, D, E1 and E2 belonging to β-Proteobacteria, were facultative CAOs and contained aoxB genes encoding the arsenite oxidase large subunit. Furthermore, they displayed various As(III) oxidation capabilities: B1, B2, E1 and E2 efficiently oxidized 1–10 mM As(III). The others showed efficient oxidation at 1–5 mM As(III), suggesting the coexistence of facultative CAOs with various As(III) oxidation capabilities in the enrichment. These results suggest that constructed enrichment and strains B1, B2, E1 and E2 can be useful for the bioremediation of arsenic-contaminated groundwater.

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YAMAZAKI, H., K. ISHII, Y. TAKAHASHI, S. MATSUYAMA, Y. KIKUCHI, Ts AMARTAIVAN, T. YAMAGUCHI, et al. "IDENTIFICATION OF OXIDATION STATES OF TRACE-LEVEL ARSENIC IN ENVIRONMENTAL WATER SAMPLES USING PIXE." International Journal of PIXE 15, no. 03n04 (January 2005): 241–47. http://dx.doi.org/10.1142/s012908350500057x.

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An enhanced sample preparation method for PIXE analysis is described allowing to separate and concentrate arsenic ions of different oxidation states in water samples. Arsenate ions are separated from arsenite ions by co-precipitating into 10 ppm indium hydroxide colloids that are generated at pH 4.0 in a 25 ml solution containing 1 ppm phosphate ions and 25 ppm sulfate ions. Arsenite ions are oxidized to the pentavalent state with permanganate ions and adsorbed by indium hydroxide colloids generated afterwards in solution. The standard procedure for collecting the colloids adsorbing arsenic ions on Nuclepore filter of 0.2 μm pores is based on an investigation of the pH-dependence of the recovery of dissolved arsenic ions and the obtained standard calibration curve covers the concentration range from 1 to 100 ppb for arsenic ions. The prepared targets were examined for 5 to 10 minutes by 3 MeV proton beam (0.7-4 nA beam currents). The lower detection limit of arsenic in a 25 ml aquatic sample is 0.3 ppb for the arsenic-precipitated targets based on the 3σ error of background counts integrated over the FWHM of arsenic peak in the PIXE spectrum. This sample preparation technique was then applied to analyze concentrations and oxidation states of arsenic in a river basin where hot springs are located upstream being possible sources for releasing arsenic in the river.

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Menezes, Regina A., Catarina Amaral, Liliana Batista-Nascimento, Claudia Santos, Ricardo Boavida Ferreira, Fréderic Devaux, Elis C. A. Eleutherio, and Claudina Rodrigues-Pousada. "Contribution of Yap1 towards Saccharomyces cerevisiae adaptation to arsenic-mediated oxidative stress." Biochemical Journal 414, no. 2 (August 12, 2008): 301–11. http://dx.doi.org/10.1042/bj20071537.

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In the budding yeast Saccharomyces cerevisiae, arsenic detoxification involves the activation of Yap8, a member of the Yap (yeast AP-1-like) family of transcription factors, which in turn regulates ACR2 and ACR3, genes encoding an arsenate reductase and a plasma-membrane arsenite-efflux protein respectively. In addition, Yap1 is involved in the arsenic adaptation process through regulation of the expression of the vacuolar pump encoded by YCF1 (yeast cadmium factor 1 gene) and also contributing to the regulation of ACR genes. Here we show that Yap1 is also involved in the removal of ROS (reactive oxygen species) generated by arsenic compounds. Data on lipid peroxidation and intracellular oxidation indicate that deletion of YAP1 and YAP8 triggers cellular oxidation mediated by inorganic arsenic. In spite of the increased amounts of As(III) absorbed by the yap8 mutant, the enhanced transcriptional activation of the antioxidant genes such as GSH1 (γ- glutamylcysteine synthetase gene), SOD1 (superoxide dismutase 1 gene) and TRX2 (thioredoxin 2 gene) may prevent protein oxidation. In contrast, the yap1 mutant exhibits high contents of protein carbonyl groups and the GSSG/GSH ratio is severely disturbed on exposure to arsenic compounds in these cells. These results point to an additional level of Yap1 contribution to arsenic stress responses by preventing oxidative damage in cells exposed to these compounds. Transcriptional profiling revealed that genes of the functional categories related to sulphur and methionine metabolism and to the maintenance of cell redox homoeostasis are activated to mediate adaptation of the wild-type strain to 2 mM arsenate treatment.

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Zargar, Kamrun, Shelley Hoeft, Ronald Oremland, and Chad W. Saltikov. "Identification of a Novel Arsenite Oxidase Gene, arxA, in the Haloalkaliphilic, Arsenite-Oxidizing Bacterium Alkalilimnicola ehrlichii Strain MLHE-1." Journal of Bacteriology 192, no. 14 (May 7, 2010): 3755–62. http://dx.doi.org/10.1128/jb.00244-10.

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ABSTRACT Although arsenic is highly toxic to most organisms, certain prokaryotes are known to grow on and respire toxic metalloids of arsenic (i.e., arsenate and arsenite). Two enzymes are known to be required for this arsenic-based metabolism: (i) the arsenate respiratory reductase (ArrA) and (ii) arsenite oxidase (AoxB). Both catalytic enzymes contain molybdopterin cofactors and form distinct phylogenetic clades (ArrA and AoxB) within the dimethyl sulfoxide (DMSO) reductase family of enzymes. Here we report on the genetic identification of a “new” type of arsenite oxidase that fills a phylogenetic gap between the ArrA and AoxB clades of arsenic metabolic enzymes. This “new” arsenite oxidase is referred to as ArxA and was identified in the genome sequence of the Mono Lake isolate Alkalilimnicola ehrlichii MLHE-1, a chemolithoautotroph that can couple arsenite oxidation to nitrate reduction. A genetic system was developed for MLHE-1 and used to show that arxA (gene locus ID mlg_0216) was required for chemoautotrophic arsenite oxidation. Transcription analysis also showed that mlg_0216 was only expressed under anaerobic conditions in the presence of arsenite. The mlg_0216 gene is referred to as arxA because of its greater homology to arrA relative to aoxB and previous reports that implicated Mlg_0216 (ArxA) of MLHE-1 in reversible arsenite oxidation and arsenate reduction in vitro. Our results and past observations support the position that ArxA is a distinct clade within the DMSO reductase family of proteins. These results raise further questions about the evolutionary relationships between arsenite oxidases (AoxB) and arsenate respiratory reductases (ArrA).

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Ike, M., T. Miyazaki, N. Yamamoto, K. Sei, and S. Soda. "Removal of arsenic from groundwater by arsenite-oxidizing bacteria." Water Science and Technology 58, no. 5 (September 1, 2008): 1095–100. http://dx.doi.org/10.2166/wst.2008.462.

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The presence of arsenic in groundwater has been of great public concern because of its high toxicity. For purification of arsenic-contaminated groundwater, bacterial oxidation of arsenite, As(III), with a chemical adsorption process was examined in this study. After As(III) oxidation to arsenate, As(V), arsenic is easily removable from contaminated groundwater because As(V) is more adsorptive to absorbents than As(III). By acclimation to As(III) of high concentrations, a mixed culture of heterotrophic bacteria with high As(III)-oxidizing activity was obtained from a soil sample that was free from contamination. With initial concentration up to 1,500 mg l−1 As(III), the mixed culture showed high As(III)-oxidizing activity at pH values of 7–10 and at temperatures of 25–35°C. The mixed culture contained several genera of heterotrophic As(III)-oxidizing and arsenic-tolerant bacteria: Haemophilus, Micrococcus, and Bacillus. Activated alumina was added to the basal salt medium containing 75 mg l−1 As(III) before and after bacterial oxidation. Arsenic removal by activated alumina was greatly enhanced by bacterial oxidation of As(III) to As(V). The isotherms of As(III) and As(V) onto activated alumina verified that bacterial As(III) oxidation is a helpful pretreatment process for the conventional adsorption process for arsenic removal.

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Castriota, Felicia, Peter-James H. Zushin, Sylvia S. Sanchez, Rachael V. Phillips, Alan Hubbard, Andreas Stahl, Martyn T. Smith, Jen-Chywan Wang, and Michele A. La Merrill. "Chronic arsenic exposure impairs adaptive thermogenesis in male C57BL/6J mice." American Journal of Physiology-Endocrinology and Metabolism 318, no. 5 (May 1, 2020): E667—E677. http://dx.doi.org/10.1152/ajpendo.00282.2019.

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The global prevalence of type 2 diabetes (T2D) has doubled since 1980. Human epidemiological studies support arsenic exposure as a risk factor for T2D, although the precise mechanism is unclear. We hypothesized that chronic arsenic ingestion alters glucose homeostasis by impairing adaptive thermogenesis, i.e., body heat production in cold environments. Arsenic is a pervasive environmental contaminant, with more than 200 million people worldwide currently exposed to arsenic-contaminated drinking water. Male C57BL/6J mice exposed to sodium arsenite in drinking water at 300 μg/L for 9 wk experienced significantly decreased metabolic heat production when acclimated to chronic cold tolerance testing, as evidenced by indirect calorimetry, despite no change in physical activity. Arsenic exposure increased total fat mass and subcutaneous inguinal white adipose tissue (iWAT) mass. RNA sequencing analysis of iWAT indicated that arsenic dysregulated mitochondrial processes, including fatty acid metabolism. Western blotting in WAT confirmed that arsenic significantly decreased TOMM20, a correlate of mitochondrial abundance; PGC1A, a master regulator of mitochondrial biogenesis; and, CPT1B, the rate-limiting step of fatty acid oxidation (FAO). Our findings show that chronic arsenic exposure impacts the mitochondrial proteins of thermogenic tissues involved in energy expenditure and substrate regulation, providing novel mechanistic evidence for arsenic’s role in T2D development.

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Sun, Ying Jie, Gang Wang, Mou Lu, Bo Fu, Ying Chen, and Qing Yuan Guo. "Analysis on Migration and Transformation Law of Arsenic between Groundwater and Fishponds in the Northen Suburb Groundwater Source Field, Zhengzhou." Applied Mechanics and Materials 71-78 (July 2011): 2948–52. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.2948.

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Based on the test results of the samples of groundwater, fishpond water, pond sediment and topsoil, analysis on migration and transformation laws of arsenic between them was executed. The SPSS statistical analysis software (V1.70) was used, in view to find out the influencing factors about migration and transformation of arsenic. It may be concluded that arsenic in groundwater was transferred to ponds through the irrigation supplies, which was adsorbed by the iron and manganese oxidation of fishpond sediment. As the changing of environment, the arsenite in the groundwater was transformed into arsenate in the fishpond water. The main factors of influencing the arsenic forms were pH、Eh、Fe and Mn in different environments. High pH and strong oxidation condition were conducive to the adsorption of arsenic in fishpond water, while low pH and strong reductive condition were conducive to the dissolution of

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Kadirvel, R., K. Sundaram, S. Mani, S. Samuel, N. Elango, and C. Panneerselvam. "Supplementation of ascorbic acid and α-tocopherol prevents arsenic-induced protein oxidation and DNA damage induced by arsenic in rats." Human & Experimental Toxicology 26, no. 12 (December 2007): 939–46. http://dx.doi.org/10.1177/0960327107087909.

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Contamination of arsenic in drinking water is associated with several human diseases including cancer. It has been reported that oxidative stress plays a vital role in arsenic-induced biochemical and molecular alterations. The aim of the present study was to improve the understanding of arsenic-induced oxidative damage to proteins and to DNA and the role of antioxidants such as ascorbic acid and α-tocopherol in alleviating arsenic-induced damages in experimental rats. A significant increase in the levels of protein oxidation, DNA strand breaks, and DNA–protein cross-links was observed in blood, liver, and kidney of rats exposed to arsenic (100 ppm in drinking water) for 30 days. Co-administration of ascorbic acid and α-tocopherol to arsenic-exposed rats showed a substantial reduction in the levels of arsenic-induced oxidative products of protein and DNA. The results of this study support that free radical–mediated toxic manifestations of arsenic and also suggest that ascorbic acid and α-tocopherol supplementation can improve the arsenic-induced molecular alterations.

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Chen, Miaomiao, Yi Li, Hong Pan, Jiuwei Teng, Ganesh Bora, Ying Wang, and Yi Zhu. "Application of Monoclinic Bismuth Vanadate in Photooxidation of Arsenic-Polluted Water." Transactions of the ASABE 63, no. 6 (2020): 1649–55. http://dx.doi.org/10.13031/trans.13754.

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HighlightsPhotooxidation of trivalent arsenic to pentavalent arsenic was catalyzed by s-m BiVO4 under visible light irradiation.The roles of catalyst, light, and oxygen were investigated.The photooxidation mechanism was studied, and a possible reaction route is proposed.Abstract. Oxidation is a necessary step for inorganic arsenic removal. In this study, monoclinic bismuth vanadate (BiVO4) was synthesized to photooxidize trivalent arsenic to pentavalent arsenic in water in the presence of light and oxygen. Light irradiation initiates photooxidation after physical absorption of arsenite on BiVO4. Addition of oxygen slightly improved the photooxidation efficiency. Photooxidation parameters were optimized; 2.6 mM of BiVO4 synthesized at pH 2 was effective to photooxidize 0.1 M of arsenite in alkaline solution, and 99.8% removal of trivalent arsenic was achieved with a photooxidation efficiency of 85.5%. Photooxidation by BiVO4 might be initiated by hydroxyl radicals resulting from irradiation by visible light. Appropriate BiVO4 morphology and alkalinity of the reaction mixture facilitated photooxidation. Keywords: Arsenic, BiVO4, Photooxidation, Speciation.

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Gonzales Contreras, Paula, Martijn Olde Weghuis, Jan Weijma, and Cees N. J. Buisman. "Recovery of Metals and Stabilization of Arsenic from (Bio-)Leaching Operations by Engineered Biological Processes." Advanced Materials Research 825 (October 2013): 536–39. http://dx.doi.org/10.4028/www.scientific.net/amr.825.536.

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This paper focuses on the application of biotechnological stabilization of arsenic from (bio-) leaching operations. One of the latest applications of the Thioteq technology is arsenic immobilization. The Thioteq-scorodite biorecovery reactor is an aerobic system to immobilise arsenic in bio-scorodite crystals. In this patented process, biological arsenite oxidation, biological ferrous iron oxidation and crystallisation reactions are simultaneously taking place. Bio-scorodite crystals can be easily harvested by sedimentation due to their relative large size of up to 160 μm. This biogenic material is classified as non-hazardous due to its very low arsenic leaching rates. Furthermore, bioscorodite crystals resemble the colour, crystal morphology, iron and arsenic content, structural water of the mineral scorodite. The operational costs related to scorodite bio-crystallization can be reduced at least 50% compared to chemical precipitation because the use of biological reactions to induce the crystallization of scorodite and the good stability properties of the produced crystals. The Thioteq-scorodite process is a reliable cost effective solution to arsenic removal and immobilization by using biological processes. The stabilization of arsenic in the form of biologically produced scorodite is an attractive technology for the compact and safe immobilization of arsenic from medium to high concentrations of arsenic in acidic process streams.

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Bolisetty, Sreenath, Noemi Reinhold, Christophe Zeder, Monica N. Orozco, and Raffaele Mezzenga. "Efficient purification of arsenic-contaminated water using amyloid–carbon hybrid membranes." Chemical Communications 53, no. 42 (2017): 5714–17. http://dx.doi.org/10.1039/c7cc00406k.

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Zhou, Ting, Jian Mei Zhou, Li Ming Zhou, Wen Li Zhang, Li Juan You, Xin Ming Wang, and Jia Yin Cao. "Conversion and Species Distribution Characteristics of Arsenical Chemical Agent in the Soil Contaminated by Chemical Weapons Abandoned by Japan." Advanced Materials Research 955-959 (June 2014): 1194–203. http://dx.doi.org/10.4028/www.scientific.net/amr.955-959.1194.

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In order to phytoremediation the soils contaminated by arsenical chemical weapons abandoned by Japan at some region of Jilin Province and ready for the estimate of the ecological safety, this paper analyzed organic species in soil with GC-MS, disscussed extraction and testing of inorganic arsenic in soil with hydrochloric acid, studied species of arsenic in soil such as available forms, valence state, and combined state, and inferred conversion process of arsenical chemical agent. The results indicate that after simple destroying and long time burial, almost all arsenical chemical agents in soil at this region are converted into inorganic arsenic due to explosion, burning, natural oxidation and microorganism, which primarily exists as As (V). Organic arsenic was only detected at where shells were buried (destroyed), in leaded shells and contaminated soil, with its content 3.65%~32.03%; Organic arsenic content of soil in other part is less than 10%. In contaminated soil of this region, water soluble arsenic and available arsenic extracted from disodium hydrogen phosphate take 0.81~2.58% and 7.49~15.96% of total arsenic respectively. Exchangeable As and binding As (Al-As, Fe-As, reducible As and Ca-As) take 40% of total arsenic, residual As takes 49.38~66.43%. The results may be used as basis for determining remedy methods and assessing ecological safety at this region.

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Drewniak, Lukasz, Renata Matlakowska, and Aleksandra Sklodowska. "Microbial Impact on Arsenic Mobilization in Zloty Stok Gold Mine." Advanced Materials Research 71-73 (May 2009): 121–24. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.121.

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The aim of this review report was to summarize knowledge about arsenic-metabolizing bacteria isolated from Zloty Stok (SW Poland) gold mine and determine their potential role in mobilization of arsenic. Three physiologically different groups of arsenic metabolizing microorganisms (arsenite oxidizers, dissmiliatory arsenate reducers and arsenic resistant microbes) were isolated from the deepest section of Gertruda Adit in Zloty Stok (SW Poland) gold mine. Twenty two strains were isolated from the rock biofilms and seven from arsenic-rich bottom sediments. Analysis of the 16S rRNA gene sequence of isolated bacteria revealed them to be members of the genera: Aeromonas, Arthrobacter, Bacillus, Brevundimonas, Chryseobacterium, Desemzia, Microbacterium, Micrococcus, Paracoccus, Pseudomonas, Rhodococcus, Serratia, Shewanella, Sinorhizobium, Sphingomonas, Stenotrophomonas and Streptomyces. All of the isolated bacteria were resistant to both inorganic arsenic species: arsenate [As(V)] and arsenite [As(III)]. One of the bottom sediments isolates (Sinorhizobium sp. M14) was able to grow on minimal salt medium using arsenite as a source of energy, and was able to release arsenic from arsenopyrite. Two strains (Shewanella sp. O23S and Aeromonas sp. O23A) isolated from bottom sediments were able to grow in the absence of oxygen, by As (V) respiration coupled with lactate oxidation. Based on arsenic metabolic activity of isolated bacteria two different mechanisms of arsenic mobilization from natural minerals (arsenopyrite FeAsS) and secondary ferrous arsenate minerals (scorodite FeAsO4) were proposed.

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Corsini, Anna, Lucia Cavalca, Gerard Muyzer, and Patrizia Zaccheo. "Effectiveness of various sorbents and biological oxidation in the removal of arsenic species from groundwater." Environmental Chemistry 11, no. 5 (2014): 558. http://dx.doi.org/10.1071/en13210.

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Environmental context Arsenic contamination of aquifers is a worldwide public health concern and several technologies have been developed to reduce the arsenic content of groundwater. We investigated the efficiency of various materials for arsenic removal from groundwater and found that iron-based sorbents have great affinity for arsenic even if groundwater composition can depress their ability to bind arsenic. Moreover, we showed that the use of microorganisms can enhance the removal of arsenic from groundwater. Abstract The AsIII and AsV adsorption capacity of biochar, chabazite, ferritin-based material, goethite and nano zero-valent iron was evaluated in artificial systems at autoequilibrium pH (i.e. MilliQ water without adjusting the pH) and at approximately neutral pH (i.e. TRIS-HCl, pH 7.2). At autoequilibrium pH, iron-based sorbents removed 200μgL–1 As highly efficiently whereas biochar and chabazite were ineffective. At approximately neutral pH, sorbents were capable of removing between 17 and 100% of AsIII and between 3 and 100% of AsV in the following order: biochar<chabazite<ferritin-based material<goethite<nano zero-valent iron. Chabazite, ferritin-based material and nano zero-valent iron oxidised AsIII to AsV and ferritin-based material was able to reduce AsV to AsIII. When tested in naturally As-contaminated groundwater, a marked decrease in the removal effectiveness occurred, due to possible competition with phosphate and manganese. A biological oxidation step was then introduced in a one-phase process (AsIII bio-oxidation in conjunction with AsV adsorption) and in a two-phase process (AsIII bio-oxidation followed by AsV adsorption). Arsenite oxidation was performed by resting cells of Aliihoeflea sp. strain 2WW, and arsenic adsorption by goethite. The one-phase process decreased As in groundwater to 85%, whereas the two-phase process removed up to 95% As, leaving in solution 6μgL–1 As, thus meeting the World Health Organization limit (10μgL–1). These results can be used in the scaling up of a two-phase treatment, with bacterial oxidation of As combined to goethite adsorption.

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Pipattanajaroenkul, Phurinat, Prinpida Sonthiphand, Supeerapat Kraidech, Satika Boonkaewwan, and Srilert Chotpantarat. "Detection of arsenite-oxidizing bacteria in groundwater with low arsenic concentration in Rayong province, Thailand." MATEC Web of Conferences 192 (2018): 03036. http://dx.doi.org/10.1051/matecconf/201819203036.

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As contamination in groundwater has become one of the global problems. It has been reported that million people around the world get adverse effects on their health by direct and indirect As-contaminated groundwater consumption. In groundwater, the most abundant As species are arsenite (As3+) and arsenate (As5+). Arsenite is more toxic and mobile than arsenate. Consequently, arsenite oxidation is considered as an important process in groundwater As bioremediation. It has been reported that arsenite-oxidizing bacteria play an important role in reducing As toxicity in contaminated groundwater environment. A functional gene involved in arsenite oxidation is aioA gene. The key objective of this study was to investigate the arsenite-oxidizing bacteria in groundwater with low arsenic concentration in Rayong province, Thailand. The results showed that the arsenite-oxidizing bacteria were detected in groundwater with low arsenic concentration. Phylogenetic analysis revealed that they were closely related to Rhizobium sp., Bradyrhizobiaceae sp., Hydrogenophaga sp., and Stenotrophomonas sp. The knowledge gained from this study will help better understand the distribution of arsenite-oxidizing bacteria in groundwater with low As concentration.

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Tongesayi, Tsanangurayi, and Ronald B. Smart. "Arsenic Speciation: Reduction of Arsenic(V) to Arsenic(III) by Fulvic Acid." Environmental Chemistry 3, no. 2 (2006): 137. http://dx.doi.org/10.1071/en05095.

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Environmental Context.Most technologies for arsenic removal from water are based on the oxidation of the more toxic and more mobile arsenic(iii) to the less toxic and less mobile arsenic(v). As a result, research effort has been focussed on the oxidation of arsenic(iii) to arsenic(v). It is equally important to explore environmental factors that enhance the reduction of arsenic(v) to arsenic(iii). An understanding of the redox cycling of arsenic could result in the development of cheaper and more efficient arsenic removal technologies, especially for impoverished communities severely threatened by arsenic contamination. Abstract.The objective of this study was to investigate the reduction of inorganic arsenic(v) with Suwannee River fulvic acid (FA) in aqueous solutions where pH, [FA], [As(v)], [As(iii)], and [Fe(iii)] were independently varied. Samples of inorganic As(v) were incubated with FA in both light and dark at constant temperature. Sterilisation techniques were employed to ensure abiotic conditions. Aliquots from the incubated samples were taken at various time intervals and analysed for As(iii) using square-wave cathodic-stripping voltammetry at a hanging mercury drop electrode. The study demonstrated the following important aspects of As speciation: (1) FA can significantly reduce As(v) to As(iii); (2) reduction of As(v) to As(iii) is a function of time; (3) both dark and light conditions promote reduction of As(v) to As(iii); (4) Fe(iii) speeds up the reduction reaction; and (5) oxidation of As(iii) to As(v) is promoted at pH 2 more than at pH 6.

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Oh, J. I., T. Urase, H. Kitawaki, M. M. Rahman, M. H. Rhahman, and K. Yamamoto. "Modeling of arsenic rejection considering affinity and steric hindrance effect in nanofiltration membranes." Water Science and Technology 42, no. 3-4 (August 1, 2000): 173–80. http://dx.doi.org/10.2166/wst.2000.0376.

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Rejection characteristics of arsenic compounds such as arsenite, dimethyl arsinic acid, and arsenate were examined regarding the effect of pH change in nanofiltration. Rejection mechanism of arsenic compounds was explained by comparing experimental rejection with calculation of the Extended Nernst-Planck model coupled with steric hindrance model. Nanofiltration membranes of the same material show similar rejection characteristics of arsenic compounds in different species. Steric hindrance and electrostatic effect in the nanofiltration membranes was well described by the model because the rejection of chloride, sulfate and arsenate ions, which exist in ionized forms at a wide pH range showed quite good agreement between model calculation and experimental result. The rejection of dimethyl arsenic acid and arsenite required the consideration of mutual interaction between membrane material and solutes as well as steric hindrance and electrostatic effect. A system with ultra low-pressure nanofiltration membrane coupled with pre-oxidation device was suggested for the treatment of arsenic in groundwater in Bangladesh.

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Martin, R., and R. Braunstein. "Arsenic growth on the gallium arsenide surface during oxidation." Journal of Physics and Chemistry of Solids 48, no. 12 (January 1987): 1207–12. http://dx.doi.org/10.1016/0022-3697(87)90007-2.

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Liang, Mengyu, Huaming Guo, and Wei Xiu. "Mechanisms of arsenite oxidation and arsenate adsorption by a poorly crystalline manganese oxide in the presence of low molecular weight organic acids." E3S Web of Conferences 98 (2019): 04009. http://dx.doi.org/10.1051/e3sconf/20199804009.

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Manganese oxides are considered as one of the effective oxides capable of oxidizing arsenite and reduce the toxicity of arsenic. Since low molecular weight organic acids (LMWOAs) commonly found in nature can act as reducing and chelating agents for manganese oxides, it is particularly important to investigate how these organic acids with different numbers of carboxyl groups like citrate and EDTA affect oxidation and adsorption of arsenic by manganese oxides. In this study, low As(V) adsorption on manganese oxide is slightly enhanced by citrate and EDTA, which results from the increase in active sites via reduction of manganese oxide by LMWOAs. However, citrate and EDTA have different effects on the oxidation of As(III). MnIII/II citrate autocatalytic cycle as a manganese-based redox system decreases As(III) oxidation rate, but EDTA does not yield autocatalysis, which slightly increases the oxidation rate of As(III). Reduction of manganese oxide by EDTA and chelation between Mn(II) and EDTA lead to exposure of more active sites. Our research highlights the different effects of low molecular weight organic acids on the reactions between arsenic and manganese oxide.

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López-Maury, Luis, Francisco J. Florencio, and José C. Reyes. "Arsenic Sensing and Resistance System in the Cyanobacterium Synechocystis sp. Strain PCC 6803." Journal of Bacteriology 185, no. 18 (September 15, 2003): 5363–71. http://dx.doi.org/10.1128/jb.185.18.5363-5371.2003.

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ABSTRACT Arsenic is one of the most important global environmental pollutants. Here we show that the cyanobacterium Synechocystis sp. strain PCC 6803 contains an arsenic and antimony resistance operon consisting of three genes: arsB, encoding a putative arsenite and antimonite carrier, arsH, encoding a protein of unknown function, and arsC, encoding a putative arsenate reductase. While arsB mutant strains were sensitive to arsenite, arsenate, and antimonite, arsC mutants were sensitive only to arsenate. The arsH mutant strain showed no obvious phenotype under the conditions tested. In vivo the arsBHC operon was derepressed by oxyanions of arsenic and antimony (oxidation state, +3) and, to a lesser extent, by bismuth (oxidation state, +3) and arsenate (oxidation state, +5). In the absence of these effectors, the operon was repressed by a transcription repressor of the ArsR/SmtB family, encoded by an unlinked gene termed arsR. Thus, arsR null mutants showed constitutive derepression of the arsBHC operon. Expression of the arsR gene was not altered by the presence of arsenic or antimony compounds. Purified recombinant ArsR protein binds to the arsBHC promoter-operator region in the absence of metals and dissociates from the DNA in the presence of Sb(III) or As(III) but not in the presence of As(V), suggesting that trivalent metalloids are the true inducers of the system. DNase I footprinting experiments indicate that ArsR binds to two 17-bp direct repeats, with each one consisting of two inverted repeats, in the region from nucleotides −34 to + 17 of the arsBHC promoter-operator.

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Hagmann, D., W. Euen, G. Schorer, and G. Metzger. "Arsenic silicide formation by oxidation of arsenic implanted silicon." Journal of Electronic Materials 18, no. 4 (July 1989): 561–65. http://dx.doi.org/10.1007/bf02657789.

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Zeng, Xian-Chun, Guoji E, Jianing Wang, Nian Wang, Xiaoming Chen, Yao Mu, Hao Li, Ye Yang, Yichen Liu, and Yanxin Wang. "Functions and Unique Diversity of Genes and Microorganisms Involved in Arsenite Oxidation from the Tailings of a Realgar Mine." Applied and Environmental Microbiology 82, no. 24 (September 23, 2016): 7019–29. http://dx.doi.org/10.1128/aem.02190-16.

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ABSTRACTThe tailings of the Shimen realgar mine have unique geochemical features. Arsenite oxidation is one of the major biogeochemical processes that occurs in the tailings. However, little is known about the functional and molecular aspects of the microbial community involved in arsenite oxidation. Here, we fully explored the functional and molecular features of the microbial communities from the tailings of the Shimen realgar mine. We collected six samples of tailings from sites A, B, C, D, E, and F. Microcosm assays indicated that all of the six sites contain both chemoautotrophic and heterotrophic arsenite-oxidizing microorganisms; their activities differed considerably from each other. The microbial arsenite-oxidizing activities show a positive correlation with soluble arsenic concentrations. The microbial communities of the six sites contain 40 phyla of bacteria and 2 phyla of archaea that show extremely high diversity. Soluble arsenic, sulfate, pH, and total organic carbon (TOC) are the key environmental factors that shape the microbial communities. We further identified 114 unique arsenite oxidase genes from the samples; all of them code for new or new-type arsenite oxidases. We also isolated 10 novel arsenite oxidizers from the samples, of which 4 are chemoautotrophic and 6 are heterotrophic. These data highlight the unique diversities of the arsenite-oxidizing microorganisms and their oxidase genes from the tailings of the Shimen realgar mine. To the best of our knowledge, this is the first report describing the functional and molecular features of microbial communities from the tailings of a realgar mine.IMPORTANCEThis study focused on the functional and molecular characterizations of microbial communities from the tailings of the Shimen realgar mine. We fully explored, for the first time, the arsenite-oxidizing activities and the functional gene diversities of microorganisms from the tailings, as well as the correlation of the microbial activities/diversities with environmental factors. The findings of this study help us to better understand the diversities of the arsenite-oxidizing bacteria and the geochemical cycle of arsenic in the tailings of the Shimen realgar mine and gain insights into the microbial mechanisms by which the secondary minerals of the tailings were formed. This work also offers a set of unique arsenite-oxidizing bacteria for basic research of the molecular regulation of arsenite oxidation in bacterial cells and for the environmentally friendly bioremediation of arsenic-contaminated groundwater.

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Yu, Hui Xin, Yi Ping Chen, and Yong Feng Jia. "Arsenic Release from Highly Contaminated Sediment during Resuspesion." Advanced Materials Research 742 (August 2013): 327–30. http://dx.doi.org/10.4028/www.scientific.net/amr.742.327.

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Arsenic release mediated by biotic and abiotic activities from sediment during resuspension was investigated in laboratory. The results showed that arsenic was released strongly during resuspension, indicating highly contaminated sediment disturbed by wave or anthropogenic process may lead to strong arsenic release and threaten the local aquatic environment. Combine with change of solid species, we can conclude that oxidation of arsenic sulfides primarily contributed to arsenic release to the aqueous phase. Arsenic release was significantly accelerated by aerobic bacteria compared with uninoculated systems, suggesting biotic oxidation of arsenic sulfides may be the dominant mechanism responsible for partition of arsenic between solid and aqueous phase during resuspension.

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V. Petrov, G., S. B. Fokina, A. Y. Boduen, I. E. Zotova, and B. F. Fidarov. "Arsenic behavior in the autoclave-hydrometallurgical processing of refractory sulfide gold-platinum-bearing products." International Journal of Engineering & Technology 7, no. 2.2 (March 5, 2018): 35. http://dx.doi.org/10.14419/ijet.v7i2.2.9897.

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Among various types of gold-bearing ores a special place belongs to the ores, which contain gold finely-dispersed in sulphide minerals, mostly in arseno-pyrite and pyrite. Autoclave-hydrometallurgical processing technologies for such raw materials seem to be of a particular interest for study. However, autoclave oxidation of sulfide-arsenic material results in significant amounts of technological solutions with high concentrations of arsenic, iron and sulfuric acid.This article represents the studies of how arsenic behaves in autoclave oxidative leaching of a refractory sulphide gold-platinum-bearing concentrate. We studied how the composition of arsenic-bearing solutions in autoclave leaching (acidity, concentration of iron and arsenic) influences the depth of arsenic precipitation when neutralized with calcium-containing reagents, which allows converting the maximum amount of arsenic together with iron in the form of iron arsenate into a stable long-term storable precipitation.

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Otte, M. L., I. M. J. Dekkers, J. Rozema, and R. A. Broekman. "Uptake of arsenic by Aster tripolium in relation to rhizosphere oxidation." Canadian Journal of Botany 69, no. 12 (December 1, 1991): 2670–77. http://dx.doi.org/10.1139/b91-335.

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Arsenic present in salt marsh soil is taken up by plants and subsequently transferred to other parts of the ecosystem. The reduced state of the bulk soil of salt marshes favours the mobility of arsenic. In the rhizosphere of plants however, arsenic may be immobilized owing to oxidation of arsenic (III) to less mobile arsenic (V) and adsorption to iron (hydr-)oxides. In a field survey iron concentrations in the vicinity of roots of Aster tripolium were higher than in the bulk soil. In a greenhouse experiment accumulation of arsenic and iron in the rhizosphere occurred, which could be due to the oxidizing activity of plant roots and (or) microorganisms. This process stimulates uptake of arsenic by salt marsh plants. The formation of an iron plaque seems to play an important role in the uptake of arsenic by salt marsh plants, as was indicated by an incubation experiment with root parts of A. tripolium. The results of the experiments indicate that iron plays a key factor in determining the mobility of arsenic in salt marsh soils and in the uptake and translocation processes in the plants. Although oxidation processes in the rhizosphere enhance uptake of arsenic, it may be an important detoxification mechanism for the plants. Key words: arsenic, Aster tripolium, iron, rhizosphere, salt marsh.

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Hassan, Zahid, Munawar Sultana, Sirajul I. Khan, Martin Braster, Wilfred F. M. Röling, and Hans V. Westerhoff. "Ample Arsenite Bio-Oxidation Activity in Bangladesh Drinking Water Wells: A Bonanza for Bioremediation?" Microorganisms 7, no. 8 (August 8, 2019): 246. http://dx.doi.org/10.3390/microorganisms7080246.

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Millions of people worldwide are at risk of arsenic poisoning from their drinking water. In Bangladesh the problem extends to rural drinking water wells, where non-biological solutions are not feasible. In serial enrichment cultures of water from various Bangladesh drinking water wells, we found transfer-persistent arsenite oxidation activity under four conditions (aerobic/anaerobic; heterotrophic/autotrophic). This suggests that biological decontamination may help ameliorate the problem. The enriched microbial communities were phylogenetically at least as diverse as the unenriched communities: they contained a bonanza of 16S rRNA gene sequences. These related to Hydrogenophaga, Acinetobacter, Dechloromonas, Comamonas, and Rhizobium/Agrobacterium species. In addition, the enriched microbiomes contained genes highly similar to the arsenite oxidase (aioA) gene of chemolithoautotrophic (e.g., Paracoccus sp. SY) and heterotrophic arsenite-oxidizing strains. The enriched cultures also contained aioA phylotypes not detected in the previous survey of uncultivated samples from the same wells. Anaerobic enrichments disclosed a wider diversity of arsenite oxidizing aioA phylotypes than did aerobic enrichments. The cultivatable chemolithoautotrophic and heterotrophic arsenite oxidizers are of great interest for future in or ex-situ arsenic bioremediation technologies for the detoxification of drinking water by oxidizing arsenite to arsenate that should then precipitates with iron oxides. The microbial activities required for such a technology seem present, amplifiable, diverse and hence robust.

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Coryell, Michael, Barbara A. Roggenbeck, and Seth T. Walk. "The Human Gut Microbiome’s Influence on Arsenic Toxicity." Current Pharmacology Reports 5, no. 6 (November 25, 2019): 491–504. http://dx.doi.org/10.1007/s40495-019-00206-4.

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Abstract Purpose of Review Arsenic exposure is a public health concern of global proportions with a high degree of interindividual variability in pathologic outcomes. Arsenic metabolism is a key factor underlying toxicity, and the primary purpose of this review is to summarize recent discoveries concerning the influence of the human gut microbiome on the metabolism, bioavailability, and toxicity of ingested arsenic. We review and discuss the current state of knowledge along with relevant methodologies for studying these phenomena. Recent Findings Bacteria in the human gut can biochemically transform arsenic-containing compounds (arsenicals). Recent publications utilizing culture-based approaches combined with analytical biochemistry and molecular genetics have helped identify several arsenical transformations by bacteria that are at least possible in the human gut and are likely to mediate arsenic toxicity to the host. Other studies that directly incubate stool samples in vitro also demonstrate the gut microbiome’s potential to alter arsenic speciation and bioavailability. In vivo disruption or elimination of the microbiome has been shown to influence toxicity and body burden of arsenic through altered excretion and biotransformation of arsenicals. Currently, few clinical or epidemiological studies have investigated relationships between the gut microbiome and arsenic-related health outcomes in humans, although current evidence provides strong rationale for this research in the future. Summary The human gut microbiome can metabolize arsenic and influence arsenical oxidation state, methylation status, thiolation status, bioavailability, and excretion. We discuss the strength of current evidence and propose that the microbiome be considered in future epidemiologic and toxicologic studies of human arsenic exposure.

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Hara, Junko, and Susumu Norota. "XAFS analysis of Arsenic bound in holocellulose extracted from organic-rich contaminated sediments." E3S Web of Conferences 98 (2019): 09010. http://dx.doi.org/10.1051/e3sconf/20199809010.

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The arsenic bound in holocellulose, a precursor of humic substances extracted from organic contaminated sediments, was investigated using XANES (x-ray adsorption near-edge structure) and EXAFS (extended x-ray absorption fine structure) with fluorescence mode. The most abundant arsenic bound in holocellulose was As-O in the first coordination sphere. Sulphur and carbon were also found in a neighbouring coordination shell around arsenic. The arsenic oxidation state was judged to be As (III) by As K edge XANES spectra as a shift to higher absorption edge energy with the increasing formal oxidation state. This arsenic speciation and bounding were well matched with biochemical mechanisms of arsenic absorption into plants.

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Reeske, Gregor, and Alan H. Cowley. "Controlling the oxidation state of arsenic in cyclic arsenic cations." Chemical Communications, no. 16 (2006): 1784. http://dx.doi.org/10.1039/b602017h.

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35

Lu, Qing, Shu Hui Zhang, and Xiao Hu. "Study on Removal Arsenic from Iron Ore with Arsenic in Sintering Process." Advanced Materials Research 284-286 (July 2011): 238–41. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.238.

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The physicochemical properties of iron ore with arsenic in South of China was analyzed by chemical analysis, XRD, high power microscope. The effects of various factors on arsenic removal in sintering process were studied and the optimal technique parameters were obtained. The results show that the mineral of iron ore with arsenic in South of China mainly is composed of magnetite and gangue, in which arsenic with 0.282% mass content exists as FeAsS and few as As2S3. The oxidation and thermal decomposition reaction of FeAsS occurs in sintering process. Under feeble oxidation atmosphere the arsenic removal rate of iron ore along with reaction temperature increases, and the holding time elongates, or the coke powder content rises. The optimal removal arsenic process parameter is: reaction temperature 1050~1100°C, holding time 8~15min, and coke powder content 6%.

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Song, Yan, Hong Ying Yang, and Lin Lin Tong. "Bioleaching of Complex Refractory Gold Ore Concentrate of China: Comparison of Shake Flask and Continuous Bioreactor." Advanced Materials Research 1130 (November 2015): 243–46. http://dx.doi.org/10.4028/www.scientific.net/amr.1130.243.

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The laboratory tests of biooxidation and cyanidation were carried out by using samples of the complex refractory gold ore from China. The elemental composition was 16.8 % iron, 18.6 % sulfur, 4.88 % arsenic，2.30 % carbon and 3.49 % antimony. Gold is assayed at 46 g/t. The arsenic oxidation of 88.11 %，carbon removal rate of 32.34 % and antimony oxidation of 23.92 % over 16d was achieved in shake flasks in the presence of the mixed culture (HQ0211: Thiobacillus ferrooxidans Leptospirillum ferrooxidans and Thiobacillus thiooxidans). The continuous bioreactor tests resulted in greater dissolution rates for arsenic, carbon and antimony, which led to a greater extent of sulphide oxidation within a shorter period of time. The maximum oxidation of arsenic and antimony was 90.72 % and 40.09 % respectively and the removal rate of carbon is 63.48% after 8d in the continuous bioreactor tests. After bioleaching, the gold recovery of the oxidation residue was 98.02 % with the cyanidation method, which was showed the biological pretreatment was applicable to the complex refractory gold ore.

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Vega, Silvia, Jan Weijma, and Cees N. J. Buisman. "Immobilization of Arsenic by a Thermoacidophilic Mixed Culture with Pyrite as Energy Source." Solid State Phenomena 262 (August 2017): 656–59. http://dx.doi.org/10.4028/www.scientific.net/ssp.262.656.

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Arsenic is an abundant element associated with a wide range of minerals and a major contaminant in metallurgical wastewater. For the immobilization of arsenic, iron arsenate in the very stable mineral scorodite (FeAsO4 2H2O) is the preferred route. Microorganisms of the natural iron cycle living at pH below 2 and high temperatures can conduct the oxidation of ferrous iron with oxygen, which is not feasible chemically at these extreme conditions. Remarkably, at similar acidic conditions and high temperature these microorganisms can also carry out the oxidation of arsenite (As(III)) to arsenate (As(V)). Using these intrinsic features of the microorganisms, we have investigated the role of a thermoacidophilic mixed culture in the oxidation of As(III) and precipitation of (As(V) in the form of scorodite from a synthetic wastewater containing 6.7mM of As(III) and 0.5%Wt pyrite as main iron Fe(II) source. The results indicate that As(III) was completely oxidized from the synthetic wastewater in the presence of pyrite and scorodite was formed only in presence of the mixed culture at a Fe/As:1.3. This is a combination of biological oxidation and biocrystallisation accomplished to the presence of pyrite not only as the main energy source for the microorganisms, but as catalyst in the As(III) oxidation reaction.

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Liu, G. J., X. R. Zhang, J. Jain, J. W. Talley, and C. R. Neal. "Stability of inorganic arsenic species in simulated raw waters with the presence of NOM." Water Supply 6, no. 6 (December 1, 2006): 175–82. http://dx.doi.org/10.2166/ws.2006.954.

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Effect of natural organic matter (NOM) on the stability of inorganic arsenic species in simulated raw water was examined at circumneutral pH. An ion chromatography–inductively coupled plasma mass spectrometry system was used for simultaneous determination of As(III) and As(V). A reduction of arsenate (As(V)) to arsenite (As(III)) was observed in the unfiltered simulated raw waters (USW). The As(V) reduction to As(III) did not occur in the simulated waters that passed through a 0.2 μm membrane (FSW). Microorganism activities is probably the major reason causing As(V) reduction in the USW. In the FSW without NOM, As(III) tended to be oxidized into As(V). The addition of 0.036 mM of Fe(II) significantly facilitated the oxidation. The presence of 10 mg/L Suwannee River NOM as C inhibited As(III) oxidation no matter whether Fe(II) existed or not. The experimental results suggest that NOM can mediate distribution of inorganic arsenic species in water, thus it is an important factor controlling the mobility and toxicity of arsenic in drinking water.

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Chou, Wen-Chien, Hsuan-Yu Chen, Sung-Liang Yu, Linzhao Cheng, Pan-Chyr Yang, and Chi V. Dang. "Arsenic suppresses gene expression in promyelocytic leukemia cells partly through Sp1 oxidation." Blood 106, no. 1 (July 1, 2005): 304–10. http://dx.doi.org/10.1182/blood-2005-01-0241.

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The mechanism by which arsenic dramatically affects gene expression remains poorly understood. Here we report that prolonged exposure of acute promyelocytic leukemia NB4 cells to low levels of arsenic trioxide increased the expression of a set of genes responsible for reactive oxygen species (ROS) production. We hypothesize that arsenic-induced ROS in turn contribute partially to altered gene expression. To identify genes responsive to arsenic-induced ROS, we used microarray gene expression analysis and identified genes that responded to arsenic and hydrogen peroxide but whose response to arsenic was reversed by an ROS scavenger, N-acetyl-L-cysteine. We found that 26% of the genes significantly responsive to arsenic might have been directly altered by ROS. We further explored the mechanisms by which ROS affects gene regulation and found that the Sp1 transcription factor was oxidized by arsenic treatment, with a corresponding decrease in its in situ binding on the promoters of 3 genes, hTERT, C17, and c-Myc, whose expressions were significantly suppressed. We conclude that ROS contributed partly to arsenic-mediated gene regulation and that Sp1 oxidation contributed to gene suppression by arsenic-induced ROS.

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Wang, Gejiao. "Microbial arsenic oxidation and chemotaxis (Abstract)." Annals of Agricultural Science, Moshtohor 56, no. 4 (April 1, 2018): 215–16. http://dx.doi.org/10.21608/assjm.2018.65524.

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Andreev, Yury V. "Arsenic Precipitation from Solutions in Autoclave-Hydrometallurgical Technology of Processing Sulphide Concentrates." Solid State Phenomena 299 (January 2020): 980–85. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.980.

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Currently, the share of gold extracted from technologically simple gold ores is steadily decreasing, which determines the involvement in the processing of refractory gold ores containing finely disseminated gold and silver in sulfides, mainly in pyrites and arsenopyrites. Autoclave oxidation is a promising method of pretreatment of the refractory sulfide-arsenic gold-bearing raw materials before cyanidation. A serious problem of auriferous ores autoclave-hydrometallurgical processing is the removal of contained arsenic into relatively harmless and capable of being kept forms. This article shows the results of behavior of arsenic during the neutralization of solid after autoclave oxidative leaching of refractory gold-containing materials.

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Yu, Lin, Yue Liu, Zhi Gang Wei, Gui Qiang Diao, Ming Sun, and Qian Yu. "Density Functional Theory Calculations of Arsenic(III) Structures on Perfect TiO₂ Anatase (1 0 1) Surface." Advanced Materials Research 233-235 (May 2011): 491–94. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.491.

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There are many areas in the world where the ground water has been contaminated by arsenic. One process to purify the water is to use TiO2 to adsorb the arsenic. As the TiO2 surface can be cleaned and reused, it has a promising potential as a water purifier. In this paper, the plane-wave function method, based on the density functional theory, has been used to calculate the structures of arsenic(III) on a perfect TiO2 anatase (1 0 1) surface. All the arsenic(III) solution species such as H3AsO3, H2AsO3-1, HAsO3-2 and AsO3-3 are put onto the surface with many different possible structures to obtain the adsorption energy. Based on the adsorption energy, the bidentate binuclear (BB) adsorption configurations of arsenic(III) on the surface are more favorable at low concentrations, whereas BB form and monodentate mononuclear (MM) form may coexist at higher concentrations. The models and results fit well with published experimental results. The results and conclusions will be of benefit to further research on arsenite adsorption and its photocatalytic oxidation on a TiO2 surface.

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Wei, Zhi Gang, Yan Di Zou, Hai Xia Zeng, Xue Chun Zhong, Zhen Jun Cheng, and Shu Guang Xie. "Density Functional Theory Calculations of Arsenic(V) Structures on Perfect TiO₂ Anatase (1 0 1) Surface." Advanced Materials Research 233-235 (May 2011): 495–98. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.495.

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There are many areas in the world where the ground water has been contaminated by arsenic. One process to purify the water is to use TiO2 to adsorb the arsenic. As the TiO2 surface can be cleaned and reused, it has a promising potential as a water purifier. In this paper, the plane-wave function method, based on the density functional theory, has been used to calculate the structures of arsenic(III) on a perfect TiO2 anatase (1 0 1) surface. All the arsenic(III) solution species such as H3AsO3, H2AsO3-1, HAsO3-2 and AsO3-3 are put onto the surface with many different possible structures to obtain the adsorption energy. Based on the adsorption energy, the bidentate binuclear (BB) adsorption configurations of arsenic(III) on the surface are more favorable at low concentrations, whereas BB form and monodentate mononuclear (MM) form may coexist at higher concentrations. The models and results fit well with published experimental results. The results and conclusions will be of benefit to further research on arsenite adsorption and its photocatalytic oxidation on a TiO2 surface.

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Manning, Bruce A., Scott E. Fendorf, Benjamin Bostick, and Donald L. Suarez. "Arsenic(III) Oxidation and Arsenic(V) Adsorption Reactions on Synthetic Birnessite." Environmental Science & Technology 36, no. 5 (March 2002): 976–81. http://dx.doi.org/10.1021/es0110170.

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Li, Jiaxin, Stephen B. Waters, Zuzana Drobna, Vicenta Devesa, Miroslav Styblo, and David J. Thomas. "Arsenic (+3 oxidation state) methyltransferase and the inorganic arsenic methylation phenotype." Toxicology and Applied Pharmacology 204, no. 2 (April 2005): 164–69. http://dx.doi.org/10.1016/j.taap.2004.12.002.

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Mitsunobu, Satoshi, Natsuko Hamanura, Takafumi Kataoka, and Fumito Shiraishi. "Arsenic attenuation in geothermal streamwater coupled with biogenic arsenic(III) oxidation." Applied Geochemistry 35 (August 2013): 154–60. http://dx.doi.org/10.1016/j.apgeochem.2013.04.005.

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Marchal, M., R. Briandet, S. Koechler, B. Kammerer, and P. N. Bertin. "Effect of arsenite on swimming motility delays surface colonization in Herminiimonas arsenicoxydans." Microbiology 156, no. 8 (August 1, 2010): 2336–42. http://dx.doi.org/10.1099/mic.0.039313-0.

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Herminiimonas arsenicoxydans is a Gram-negative bacterium able to detoxify arsenic-contaminated environments by oxidizing arsenite [As(III)] to arsenate [As(V)] and by scavenging arsenic ions in an extracellular matrix. Its motility and colonization behaviour have been previously suggested to be influenced by arsenite. Using time-course confocal laser scanning microscopy, we investigated its biofilm development in the absence and presence of arsenite. Arsenite was shown to delay biofilm initiation in the wild-type strain; this was partly explained by its toxicity, which caused an increased growth lag time. However, this delayed adhesion step in the presence of arsenite was not observed in either a swimming motility defective fliL mutant or an arsenite oxidase defective aoxB mutant; both strains displayed the wild-type surface properties and growth capacities. We propose that during the biofilm formation process arsenite acts on swimming motility as a result of the arsenite oxidase activity, preventing the switch between planktonic and sessile lifestyles. Our study therefore highlights the existence, under arsenite exposure, of a competition between swimming motility, resulting from arsenite oxidation, and biofilm initiation.

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Jiang, J. Q. "Removing arsenic from groundwater for the developing world - a review." Water Science and Technology 44, no. 6 (September 1, 2001): 89–98. http://dx.doi.org/10.2166/wst.2001.0348.

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This paper is principally concerned with summarising the experience to date of treating arsenic containing ground/surface water by oxidation, coagulation/precipitation and adsorption processes. Arsenic (As) has been verified through epidemiological evidence as one of the most carcinogenic and toxic substances in surface and ground water. Oxidation, coagulation/precipitation, and adsorption have been widely used in arsenic removal and the study results demonstrated that these technologies can remove arsenic from ground/surface water efficiently; the residual arsenic concentration in the effluent could be in the range of 5-10 μg/l, against the influent arsenic concentration in the range of 10-500 μg/l. However, these technologies need to be surveyed in order to validate the efficiency, cost and maintenance requirments by considering social and economic situations and the availability of the local resources in the developing world.

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Simon, Grigore, Hui Huang, James E. Penner-Hahn, Stephen E. Kesler, and Li-Shun Kao. "Oxidation state of gold and arsenic in gold-bearing arsenian pyrite." American Mineralogist 84, no. 7-8 (August 1, 1999): 1071–79. http://dx.doi.org/10.2138/am-1999-7-809.

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50

Dave, Shailesh R., and K. H. Gupta. "Interactions of Acidithiobacillus ferrooxidans with Heavy Metals, Various Forms of Arsenic and Pyrite." Advanced Materials Research 20-21 (July 2007): 423–26. http://dx.doi.org/10.4028/www.scientific.net/amr.20-21.423.

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An arsenic resistant ferrous iron oxidizing bacterium Acidithiobacillus ferrooxidans (GenBank no. EF010878) was isolated from reactor leachate. The reactor leachate showed extreme environmental parameters. Ferrous iron concentrations of more than 60 g/L were found to be inhibitory in the presence and absence of arsenite. Ks values of 12.5 and 8.0 g/L ferrous sulphate and Vmax of 0.124 and 0.117 g/L/h/0.8 mg of protein were found in the presence and absence of arsenite respectively. At 14.9 g/L of arsenite and arsenate the culture showed 26.8 and 59.7 % ferrous iron oxidizing activity respectively. Amongst the metals studied, copper was found to be more toxic as compared to nickel and zinc. In the presence of 3.51 g/L nickel or 4.68 g/L zinc, about 30 % biooxidation activity was registered. In the pyrite oxidation study 87, 67 and 64 % of pyrite oxidation was found and 2.02, 3.19 and 5.96 g/L total iron was solubilized with 5, 10 and 20 g/L of pyrite respectively. The isolate was also able to oxidize refractory arsenopyrite gold ore and 0.531 g/L of arsenic was solubilized along with 0.872 g/L of soluble total iron. During this period the numbers of planktonic bacteria increased from 2.4 x 106 to 1.0 x 108 cells/mL.

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Journal articles on the topic 'Arsenic – Oxidation'

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