Chapter 15 Arsenic Speciation in Solid Phases of Geothermal Fields

The purpose of the present study was to assess arsenic (As) speciation in rice from West Bengal, India, in order to improve understanding of the health risk posed by arsenic in Indian rice. Rice is a potentially important route of human exposure to arsenic, especially in populations with rice-based diets. However, arsenic toxicity varies greatly with species. Determination of arsenic (As) species in rice is necessary because inorganic As species are more toxic than organic As. Total arsenic was determined by inductively coupled plasma mass spectrometry; arsenite, arsenate, monomethylarsonic acid, and dimethyarsinic acid were quantified by high-performance liquid chromatography- inductively coupled plasma mass spectrometry. The analysis of a rice flour certified reference material (SRM-1568-a) were evaluated for quality assurance. The use of 2M TFA for extraction with an isocratic mobile phase was optimized for extraction and employed for arsenic speciation in rice. The extraction method showed a high recovery of arsenic. Most of the As species in rice were noticed to be inorganic [Arsenite (As-III), Arsenate As-V]. It appeared very clear from the present study that inorganic arsenic shared maximum arsenic load in rice straw while in grains it is considerably low. As species recovered from rice grain and straw are principally As-III and As-V with a little share of DMA and almost non-detectable MMA and As-B. The order of As species in rice grain revealed in this study were As-III (54.5-65.4 %)>As-V(21.2-28.3%)>DMA(5.2%).

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Removal of Tramp Elements within 7075 Alloy by Super-Gravity Aided Rheorefining Method

Metals ◽

10.3390/met8090701 ◽

2018 ◽

Vol 8 (9) ◽

pp. 701 ◽

Cited By ~ 5

Author(s):

Lei Guo ◽

Xiaochun Wen ◽

Qipeng Bao ◽

Zhancheng Guo

Keyword(s):

Heat Treatment ◽

Liquid Phase ◽

7075 Aluminum Alloy ◽

Total Removal ◽

Tramp Element ◽

Removal Ratio ◽

Gravity Coefficient ◽

Flow Through ◽

Solid Phases ◽

7075 Alloy

An investigation was made on the super-gravity aided rheorefining process of recycled 7075 aluminum alloy in order to remove tramp elements. The separation temperatures in this study were selected as 609 °C, 617 °C and 625 °C. And the gravity coefficients were set as 400 G, 700 G, 1000 G. The finely distributed impurity inclusions will aggregate to the grain boundaries of Al-enriched phase during heat treatment. In the field of super-gravity, the liquid phase composed of tramp elements Zn, Cu, Mg et al. will flow through the gaps between solid Al-enriched grains and form into filtrate. Both the weight of filtrate and removal ratio of tramp element improved with the increase of gravity coefficient. The total removal ratio of tramp element decreased with the fall of temperature due to the flowability deterioration of liquid phase. The time for effective separation of liquid/solid phases with super-gravity can be restricted within 1 min.

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Combined Use of Structure Analysis, Studies of Molecular Association in Solution, and Molecular Modelling to Understand the Different Propensities of Dihydroxybenzoic Acids to Form Solid Phases

Pharmaceutics ◽

10.3390/pharmaceutics13050734 ◽

2021 ◽

Vol 13 (5) ◽

pp. 734

Author(s):

Aija Trimdale ◽

Anatoly Mishnev ◽

Agris Bērziņš

Keyword(s):

Crystal Structure ◽

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Structure Analysis ◽

Crystal Structure Analysis ◽

Molecular Association ◽

Hydroxyl Groups ◽

Solid Phases ◽

Solvent Molecules ◽

Dynamics Simulations

The arrangement of hydroxyl groups in the benzene ring has a significant effect on the propensity of dihydroxybenzoic acids (diOHBAs) to form different solid phases when crystallized from solution. All six diOHBAs were categorized into distinctive groups according to the solid phases obtained when crystallized from selected solvents. A combined study using crystal structure and molecule electrostatic potential surface analysis, as well as an exploration of molecular association in solution using spectroscopic methods and molecular dynamics simulations were used to determine the possible mechanism of how the location of the phenolic hydroxyl groups affect the diversity of solid phases formed by the diOHBAs. The crystal structure analysis showed that classical carboxylic acid homodimers and ring-like hydrogen bond motifs consisting of six diOHBA molecules are prominently present in almost all analyzed crystal structures. Both experimental spectroscopic investigations and molecular dynamics simulations indicated that the extent of intramolecular bonding between carboxyl and hydroxyl groups in solution has the most significant impact on the solid phases formed by the diOHBAs. Additionally, the extent of hydrogen bonding with solvent molecules and the mean lifetime of solute–solvent associates formed by diOHBAs and 2-propanol were also investigated.

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Compaction of peat cover over desulfurized gold mine tailings changes: Arsenic speciation and mobility

Applied Geochemistry ◽

10.1016/j.apgeochem.2021.104923 ◽

2021 ◽

Vol 128 ◽

pp. 104923

Author(s):

T.V. Rakotonimaro ◽

M. Guittony ◽

C.M. Neculita

Keyword(s):

Mine Tailings ◽

Arsenic Speciation ◽

Gold Mine ◽

Gold Mine Tailings

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ZnOTe Compounds Grown by DC-Magnetron Co-Sputtering

Coatings ◽

10.3390/coatings11050570 ◽

2021 ◽

Vol 11 (5) ◽

pp. 570

Author(s):

Olga Sánchez ◽

Manuel Hernández-Vélez

Keyword(s):

Molar Fraction ◽

Variable Parameter ◽

Point Of View ◽

X Ray Diffraction ◽

X Ray ◽

Sample Series ◽

Solid Phases ◽

The One ◽

High Bulk ◽

Substrate Sample

ZnOTe compounds were grown by DC magnetron cosputtering from pure Tellurium (Te) and Zinc (Zn) cathodes in O2/Ar atmosphere. The applied power on the Zn target was constant equal to 100 W, while the one applied on the Te target took two values, i.e., 5 W and 10 W. Thus, two sample series were obtained in which the variable parameter was the distance from the Te targets to the substrate. Sample compositions were determined by Rutherford Backscattering Spectroscopy (RBS) experiments. Structural analysis was done using X-Ray diffraction (XRD) spectrometry and the growth of the hexagonal w-ZnO phase was identified in the XRD spectra. RBS results showed high bulk homogeneity of the samples forming ZnOTe alloys, with variable Te molar fraction (MF) ranging from 0.48–0.6% and from 1.9–3.1% for the sample series obtained at 5 W and 10 W, respectively. The results reflect great differences between the two sample series, particularly from the structural and optical point of view. These experiments point to the possibility of Te doping ZnO with the permanence of intrinsic defects, as well as the possibility of the formation of other Te solid phases when its content increases. The results and appreciable variations in the band gap transitions were detected from Photoluminescence (PL) measurements.

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Importance of monitoring arsenic methylation metabolism in acute promyelocytic leukemia patients receiving the treatment of arsenic trioxide

Experimental Hematology and Oncology ◽

10.1186/s40164-021-00205-6 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Yu Zheng ◽

Yuan-Fei Mao ◽

Hui-Jin Zhao ◽

Li Chen ◽

Li-Ning Wang ◽

...

Keyword(s):

Arsenic Trioxide ◽

Acute Promyelocytic Leukemia ◽

Arsenic Speciation ◽

Promyelocytic Leukemia ◽

Chronic Liver ◽

Dimethylarsinic Acid ◽

Metabolic Pattern ◽

Methylation Index ◽

Arsenic Methylation

Abstract Background Arsenic trioxide [ATO, inorganic arsenite (iAsIII) in solution] plays an important role in the treatment of acute promyelocytic leukemia (APL). However, the long-term adverse effects (AEs) and the retention of arsenic among APL patients are rarely reported. In this study, we focused on arsenic methylation metabolism and its relationship with chronic hepatic toxicity, as we previously reported, among APL patients who had finished the treatment of ATO. Methods A total of 112 de novo APL patients who had completed the ATO-containing treatment were enrolled in the study. Arsenic species [iAsIII, inorganic arsenate (iAsV), and their organic metabolites, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)] in patients’ plasma, urine, hair and nails were detected by high-performance liquid chromatography combined with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Eighteen single nucleotide polymorphisms (SNPs) of the arsenic (+ 3 oxidative state) methylation transferase (AS3MT) gene, which was known as the main catalyzer for arsenic methylation, were tested with the polymerase chain reaction method. Results The study showed the metabolic pattern of arsenic in APL patients undergoing and after the treatment of ATO, in terms of total arsenic (TAs) and four species of arsenic. TAs decreased to normal after 6 months since cessation of ATO. But the arsenic speciation demonstrated significantly higher portion of iAsIII in patient’s urine (40.08% vs. 1.94%, P < 0.001), hair (29.25% vs. 13.29%, P = 0.002) and nails (30.21% vs. 13.64%, P = 0.003) than the healthy controls’, indicating a decreased capacity of arsenic methylation metabolism after the treatment of ATO. Urine primary methylation index (PMI) was significantly lower in patients with both chronic liver dysfunction (0.14 vs. 0.28, P = 0.047) and hepatic steatosis (0.19 vs. 0.3, P = 0.027), suggesting that insufficient methylation of arsenic might be related to chronic liver disorders. Two SNPs (A9749G and A27215G) of the AS3MT gene were associated with impaired urine secondary methylation index (SMI). Conclusions The long-term follow-up of arsenic speciation indicated a decreased arsenic methylation metabolism and a probable relationship with chronic hepatic disorders among APL patients after the cessation of ATO. Urine PMI could be a monitoring index for chronic AEs of ATO, and the SNPs of AS3MT gene should be considered when determining the dosage of ATO.

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