scholarly journals Seagrass-Mediated Phosphorus and Iron Solubilization in Tropical Sediments

2017 ◽  
Vol 51 (24) ◽  
pp. 14155-14163 ◽  
Author(s):  
Kasper Elgetti Brodersen ◽  
Klaus Koren ◽  
Maria Moßhammer ◽  
Peter J. Ralph ◽  
Michael Kühl ◽  
...  
Keyword(s):  
Iron Solubilization

scholarly journals Statistical Treatment of Bleaching Kaolin by Iron Removal

2017 ◽  
Vol 57 (4) ◽  
Author(s):  
Román Ángel Hernández Hernández ◽  
Felipe Legorreta García ◽  
Leticia Esperanza Hernández Cruz ◽  
Antonia Martínez Luévanos
Keyword(s):  
Atmospheric Pressure ◽  
Statistical Treatment ◽  
Influential Factors ◽  
Iron Removal ◽  
Dissolved Iron ◽  
Dependent Variables ◽  
Leaching Experiments ◽  
Effects Of Temperature ◽  
Iron Solubilization

In the present study, oxalic acid was used as a leaching reagent to remove iron from a kaolin mineral. Statistical analysis was conducted to determine the most influential factors in the dissolution of iron from the kaolin mineral. Our goal was ferric iron solubilization and its reduction to ferrous iron to improve the iron removal in the acid medium. Leaching experiments were conducted at atmospheric pressure. A two-level factorial design of the type 2<sup>4</sup> was utilized. The dependent variable was the percentage of dissolved iron, and the dependent variables in this study were acid concentration (0.35 and 0.50 M), temperature (75 °C and 100 °C), leaching time (2 and 4 h), and pH (1.5 and 2.5). An analysis of variance revealed that the effects of the factors temperature (b), pH (d), and the combined effects of temperature and time (bc) resulted in the maximum dissolution of iron of 88% at 100 °C, giving a kaolin mineral with a whiteness index 93.50%.

scholarly journals Ash iron mobilization in volcanic eruption plumes

2014 ◽  
Vol 14 (23) ◽  
pp. 32535-32581 ◽  
Author(s):  
G. Hoshyaripour ◽  
M. Hort ◽  
B. Langmann
Keyword(s):  
Volcanic Eruption ◽  
Freezing Point ◽  
Iron Mobilization ◽  
Cloud Processing ◽  
Surface Ocean ◽  
Physicochemical Interactions ◽  
Leaching Experiments ◽  
Ph Conditions ◽  
Iron Solubilization ◽  
Dissolution Efficiency

Abstract. It has been shown that volcanic ash fertilizes the Fe-limited areas of the surface ocean through releasing soluble iron. As ash iron is mostly insoluble upon the eruption, it is hypothesized that heterogeneous in-plume and in-cloud processing of the ash promote the iron solubilization. Direct evidences concerning such processes are, however, lacking. In this study, a 1-D numerical model is developed to simulate the physicochemical interactions of gas–ash–aerosol in volcanic eruption plumes focusing on the iron mobilization processes at temperatures between 600 and 0 °C. Results show that sulfuric acid and water vapor condense at ~150 and ~50 °C on the ash surface, respectively. This liquid phase then efficiently scavenges the surrounding gases (>95% of HCl, 3–20% of SO2 and 12–62% of HF) forming an extremely acidic coating at the ash surface. The low pH conditions of the aqueous film promote acid-mediated dissolution of the Fe-bearing phases present in the ash material. We estimate that 0.1 to 33% of the total iron available at the ash surface is dissolved in the aqueous phase before the freezing point is reached. The efficiency of dissolution is controlled by the halogen content of the erupted gas as well as the mineralogy of the iron at ash surface: elevated halogen concentrations and presence of Fe2+-carrying phases lead to the highest dissolution efficiency. Findings of this study are in agreement with the data obtained through leaching experiments.

Proteolytic Digestion of Meat Is Not Necessary for Iron Solubilization

1989 ◽  
Vol 119 (10) ◽  
pp. 1418-1422 ◽  
Author(s):  
Charles E. Carpenter ◽  
Arthur W. Mahoney
Keyword(s):  
Proteolytic Digestion ◽  
Iron Solubilization

scholarly journals Ash iron mobilization through physicochemical processing in volcanic eruption plumes: a numerical modeling approach

2015 ◽  
Vol 15 (16) ◽  
pp. 9361-9379 ◽  
Author(s):  
G. A. Hoshyaripour ◽  
M. Hort ◽  
B. Langmann
Keyword(s):  
Volcanic Eruption ◽  
Freezing Point ◽  
Iron Mobilization ◽  
Cloud Processing ◽  
Surface Ocean ◽  
Physicochemical Interactions ◽  
Leaching Experiments ◽  
Ph Conditions ◽  
Iron Solubilization ◽  
Dissolution Efficiency

Abstract. It has been shown that volcanic ash fertilizes the Fe-limited areas of the surface ocean through releasing soluble iron. As ash iron is mostly insoluble upon the eruption, it is hypothesized that heterogeneous in-plume and in-cloud processing of the ash promote the iron solubilization. Direct evidences concerning such processes are, however, lacking. In this study, a 1-D numerical model is developed to simulate the physicochemical interactions of the gas–ash–aerosol in volcanic eruption plumes focusing on the iron mobilization processes at temperatures between 600 and 0 °C. Results show that sulfuric acid and water vapor condense at ~ 150 and ~ 50 °C on the ash surface, respectively. This liquid phase then efficiently scavenges the surrounding gases (> 95 % of HCl, 3–20 % of SO2 and 12–62 % of HF) forming an extremely acidic coating at the ash surface. The low pH conditions of the aqueous film promote acid-mediated dissolution of the Fe-bearing phases present in the ash material. We estimate that 0.1–33 % of the total iron available at the ash surface is dissolved in the aqueous phase before the freezing point is reached. The efficiency of dissolution is controlled by the halogen content of the erupted gas as well as the mineralogy of the iron at ash surface: elevated halogen concentrations and presence of Fe2+-carrying phases lead to the highest dissolution efficiency. Findings of this study are in agreement with the data obtained through leaching experiments.

Effect of Acid Pretreatment on the Stability of EDTA, Cysteine, Lactic and Succinic Acid Complexes of Various Iron Sources in a Wheat Flake Cereal

1987 ◽  
Vol 50 (7) ◽  
pp. 587-597
Author(s):  
D. B. NADEAU ◽  
F. M. CLYDESDALE
Keyword(s):  
Succinic Acid ◽  
Ferrous Sulfate ◽  
Iron Complex ◽  
Molar Ratio ◽  
Acid Pretreatment ◽  
Gastrointestinal Ph ◽  
Iron Solubilization ◽  
The Stability ◽  
Reducing Potential

An in vitro incubation at pH 2 of EDTA, cysteine, lactic or succinic acids with each of five iron sources, [hydrogen (HRI) and electrolytically reduced elemental iron (ERI), ferric chloride (FeCl3), ferrous sulfate (FeSO4) and ferric orthophosphate (FOP)] at a 10:1 molar ratio (ligand:iron) was evaluated for its effect on iron solubilization in a wheat flake cereal subjected to a sequential gastrointestinal pH treatment from endogenous pH (E) to 2 to 6. Incubation significantly enhanced the iron solubilizing potential of EDTA at each pH with HRI and ERI, while lactic and succinic acids were similarly effective with FeSO4 and FeCl3 at pH 2. The reducing potential of cysteine, along with its role as a ligand, generated substantial amounts of Fe+ 2 (pH 2) at the apparent expense of complexed iron. However, with the exception of ERI (pH E), incubation did not increase cysteine's effectiveness in producing more soluble iron (ionic + complexed). This indicates that pH was the major solubilizing factor. Due to FOP's relative insolubility, incubation proved ineffective in all instances. These in vitro results indicate that acid incubation to form a ligand-iron complex has the potential to improve bioavailability of iron.

scholarly journals Iron solubilization during anaerobic growth of acidophilic microorganisms with a polymetallic sulfide ore

2015 ◽  
Vol 75 ◽  
pp. 77-84 ◽  
Author(s):  
Paul R. Norris ◽  
Oliver J.P. Gould ◽  
Thomas J. Ogden
Keyword(s):  
Anaerobic Growth ◽  
Acidophilic Microorganisms ◽  
Sulfide Ore ◽  
Iron Solubilization

Pyrite Oxidation by Halotolerant, Thermotolerant Bacteria

2009 ◽  
Vol 71-73 ◽  
pp. 75-78 ◽  
Author(s):  
Paul R. Norris ◽  
James Le C. Nicolle ◽  
L. Calvo-Bado ◽  
V. Angelatou
Keyword(s):  
16S Rrna ◽  
Novel Species ◽  
Enrichment Culture ◽  
Pyrite Oxidation ◽  
Aegean Sea ◽  
Rrna Gene ◽  
The Novel ◽  
16S Rrna Gene Sequences ◽  
Thermotolerant Bacteria ◽  
Iron Solubilization

Thermotolerant “Thiobacillus prosperus”-like bacteria were enriched from warm, acidic sediments of the island of Milos in the Aegean Sea. Analysis of 16S rRNA gene sequences indicated at least two thermotolerant species, with at least one of them present in similar niches at Vulcano, Italy. Iron solubilization in a pyrite-enrichment culture at 47°C was most rapid in the presence of NaCl at 30 g.l 1. One of the novel species (strain M7) grew in pure culture on pyrite with NaCl at 50 g.l-1, but iron solubilization was most rapid with 20 g NaCl.l 1 at just below 50°C.

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