scholarly journals Regulation of dissolved phosphate through incorporation into schwertmannite

2020 ◽  
Author(s):  
Helen E. King ◽  
Stan Bakker ◽  
Gijs Munnecom ◽  
Felipe Gomez
Keyword(s):  
Inductively Coupled Plasma ◽  
Mine Drainage ◽  
Critical Concentration ◽  
Ion Pairs ◽  
Atomic Emission ◽  
Inductively Coupled ◽  
Tinto River ◽  
Rio Tinto ◽  
Speciation Modelling ◽  
Río Tinto

<p>Phosphate is known to absorb strongly to schwertmannite (Fe<sub>8</sub>O<sub>8</sub>(OH)<sub>6</sub>(SO<sub>4</sub>)·nH<sub>2</sub>O)<sup>1</sup> and as such, schwertmannite has been proposed to limit phosphate in solution in acid mine drainage (AMD) environments. This in turn will limit phosphate availability to the micro-organisms that live in and propagate AMD<sup>2</sup>. Here we have studied sediment samples from the Rio Tinto river in Spain collected during Europlanet field area visit to verify whether phosphate can be incorporated into sulphate-rich minerals in this river. The minerals were identified using X-ray diffraction. Our analyses show that the concentration of phosphate in the river is in the nM range. Digestion of modern sediments in nitric acid followed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis indicate that sites with sulphate-rich minerals are correlated with elevated phosphate concentrations. In addition, phosphate is also retained in ancient sediments that are dominated by goethite (FeO(OH)).</p><p>We have also conducted experiments to explore the competition between Fe<sup>3+</sup>, phosphate and sulphate ions in solution as well as the effect of this on schwertmannite nucleation. UV-Vis and Raman spectroscopy demonstrate that contact ion pairs form between Fe<sup>3+</sup> and phosphate or sulphate in solution. Particularly, phosphate and sulphate compete for Fe<sup>3+ </sup>in solution consistent with predictions by the solution speciation modelling program PHREEQC. Our experiments also show that above a critical concentration, phosphate retards the nucleation of schwertmannite. As this critical concentration is above that found in Rio Tinto river fluids, phosphate is expected to have a limited role in schwertmannite precipitation, but, its concentration is regulated by its incorporation into schwertmannite and other sulphate-bearing phases in AMD systems.</p><p>References</p><p><sup>1</sup>Eskandarpour et al. 2006, Material Transactions, 1832. <sup>2</sup>Chen et al. 2015, ISME, 1579.</p>

Rapid Catalyst Capture Enables Metal-Free Parahydrogen-Based Hyperpolarized Contrast Agents

2018 ◽  
Author(s):  
Danila Barskiy ◽  
Lucia Ke ◽  
Xingyang Li ◽  
Vincent Stevenson ◽  
Nevin Widarman ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Contrast Agents ◽  
Inductively Coupled Plasma ◽  
Organometallic Compounds ◽  
Atomic Emission ◽  
Platinum Group Metals ◽  
Resonance Spectroscopy ◽  
Plasma Atomic Emission ◽  
Inductively Coupled

<p>Hyperpolarization techniques based on the use of parahydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of parahydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals and their administration in vivo should be avoided.</p> <p><br></p><p>Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 seconds) Ir-based catalyst capture by metal scavenging agents can produce pure parahydrogen-based hyperpolarized contrast agents as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.</p>

Rapid Catalyst Capture Enables Metal-Free Parahydrogen-Based Hyperpolarized Contrast Agents

2018 ◽  
Author(s):  
Danila Barskiy ◽  
Lucia Ke ◽  
Xingyang Li ◽  
Vincent Stevenson ◽  
Nevin Widarman ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Contrast Agents ◽  
Inductively Coupled Plasma ◽  
Organometallic Compounds ◽  
Atomic Emission ◽  
Platinum Group Metals ◽  
Resonance Spectroscopy ◽  
Plasma Atomic Emission ◽  
Inductively Coupled

<p>Hyperpolarization techniques based on the use of parahydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of parahydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals and their administration in vivo should be avoided.</p> <p><br></p><p>Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 seconds) Ir-based catalyst capture by metal scavenging agents can produce pure parahydrogen-based hyperpolarized contrast agents as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.</p>

Silicate analysis of carbonated rocks using ICP-AES with calibration by the concentration ratio

2020 ◽  
Vol 86 (5) ◽  
pp. 16-21
Author(s):  
T. A. Karimova ◽  
G. L. Buchbinder ◽  
S. V. Kachin
Keyword(s):  
Inductively Coupled Plasma ◽  
Concentration Ratio ◽  
Total Error ◽  
Atomic Emission ◽  
Emission Spectrometry ◽  
Calibration Error ◽  
Plasma Atomic Emission Spectrometry ◽  
Standard Samples ◽  
Inductively Coupled ◽  
Carbonate Materials

Calibration by the concentration ratio provides better metrological characteristics compared to other calibration modes when using the inductively coupled plasma atomic emission spectrometry (ICP-AES) for analysis of geological samples and technical materials on their base. The main reasons for the observed improvement are: i) elimination of the calibration error of measuring vessels and the error of weighing samples of the analyzed materials from the total error of the analysis; ii) high intensity of the lines of base element; and iii) higher accuracy of measuring the ratio of intensities compared to that of measuring the absolute intensities. Calcium oxide is better suited as a base when using calibration by the concentration ratio in analysis of carbonate rocks, technical materials, slags containing less than 20% SiO2 and more than 20% CaO. An equation is derived to calculate the content of components determined in carbonate materials when using calibration by the concentration ratio. A method of ICP-AES with calibration by the concentration ratio is developed for determination of CaO (in the range of contents 20 – 100%), SiO2 (2.0 – 35%), Al2O3 (0.1 – 30%), MgO (0.1 – 20%), Fe2O3 (0.5 – 40%), Na2O (0.1 – 15%), K2O (0.1 – 5%), P2O5 (0.001 – 2%), MnO (0.01 – 2%), TiO2 (0.01 – 2.0%) in various carbonate materials. Acid decomposition of the samples in closed vessels heated in a HotBlock 200 system is proposed. Correctness of the procedure is confirmed in analysis of standard samples of rocks. The developed procedure was used during the interlaboratory analysis of the standard sample of slag SH17 produced by ZAO ISO (Yekaterinburg, Russia).

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