Sorption and precipitation of iron of Kaolinite. II. Sorption isotherms and their interpretation in terms of Iron(III) ionic equilibria

Soil Research ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 199 ◽  
Author(s):  
AW Fordham
Keyword(s):  
Iron Concentration ◽  
Ferric Hydroxide ◽  
Sorption Isotherms ◽  
Ionic Species ◽  
Total Iron ◽  
Polymerization Process ◽  
Quasi Equilibrium ◽  
Clay Surface ◽  
Ionic Equilibria ◽  
Ph Range

The sorption of iron(III) by kaolinite was studied in different media as a function of iron concentration, pH, and time, with such low concentrations of total iron that precipitation was excluded over most of the pH range examined. The reaction continued at a measurable rate for several weeks but a state of quasi-equilibrium, independent of the medium and of clay : solution ratio, was achieved in about 1 week. The amount of iron sorbed from the most acidic solutions was relatively low but increased markedly with increasing pH. Total iron concentrations measured in equilibrium with the clay were resolved by computer into concentrations of the component ionic species, which were then plotted against the total amount of iron sorbed. Unique relationships were found within specified pH ranges. From pH2O to 2.7, the amount of iron sorbed was correlated with the concentration of the species FeOH2+ and, from about pH 2.7 to 3.6, with the concentration of Fe(OH)2+. Specific sorption of these species by the clay is discussed. At higher pH values and prior to the precipitation of iron, other factors contributed to the sorption of iron. A reaction of monomeric iron species from solution with iron already sorbed by the clay is proposed, leading to the formation of polymers on the clay surface. Under suitable conditions of iron concentration and pH, precipitation of ferric hydroxide, probably a later stage of the polymerization process, occurred on the clay surface, in accordance with a well-defined solubility product relationship.

Sorption and precipitation of iron on kaolinite. III. The solubility of iron(III) hydroxides precipated in the presence of kaolinite

Soil Research ◽  
1970 ◽  
Vol 8 (1) ◽  
pp. 107 ◽  
Author(s):  
AW Fordham
Keyword(s):  
Electron Microscope ◽  
Solubility Product ◽  
Reaction Times ◽  
Ionic Species ◽  
Total Iron ◽  
X Ray ◽  
Acidic Solutions ◽  
Ph Values ◽  
Solubility Products ◽  
Ph Range

Iron(111) hydroxides were precipitated upon kaolinite suspended in acidic solutions of either 0.15M NaCl or 0.15M NaClO4. The progress of the reaction was followed for up to 15 weeks by periodic measurements of pH values and total iron(111) concentrations in solution. Total iron(m) concentrations varied from 1 0 - 3 ~ to 2 x 10-7 and pH values from 2.2 to 4.4. In NaCl media, steady state conditions were reached within 4-5 weeks. Allowing for the various iron(III) ionic species present in the solution phase, the solubility product *K++S2 (= [Fe(OH)+2]/aH+) was found to be 4.9 x 10-3 (S.D. = 0.7 x 10-3 log*K++S2 = - 2.31; log Kso = - 38.9). Although the initial precipitates were amorphous, the presence of �-FeOOH in aged suspensions was detected by X-ray analysis, in agreement with electron microscope observations. In NaClO4 media, the solubility of precipitates decreased rapidly during the first 3 weeks and relatively slowly thereafter. Although equilibrium was obviously not established within 5 weeks and possibly not within 15 weeks, values of solubility products, constant over the whole pH range, were derived from results at both reaction times. For suspensions aged for 5 weeks, *K++S2 was 4.85 x 10-3 (S.D. = 0.75 x 10-3 ; logKso = -38.9), whilst for those at 15 weeks, *K++S2 was 2.45 x 10-3 (S.D. = 0.3 x 10-3; log Kso = -39.2). X-ray and infra-red analyses and electron microscope examination indicated the presence of lepidocrocite in the aged products. There was no evidence that either the type or the solubility of products formed on aging was influenced by the presence of kaolinite, although the clay accelerated the rate of crystal growth.

THE IMPACT OF WIND CONDITIONS ON THE LEVELS OF TOTAL IRON CONTENT IN THE SEA OF AZOV

2017 ◽  
Author(s):  
Yuri Fedorov ◽  
Yuri Fedorov ◽  
Irina Dotsenko ◽  
Irina Dotsenko ◽  
Leonid Dmitrik ◽  
...  
Keyword(s):  
Bottom Sediments ◽  
Iron Content ◽  
Iron Concentration ◽  
Total Iron ◽  
Sea Of Azov ◽  
Open Area ◽  
The Sea Of Azov ◽  
Dissolved Iron ◽  
The Impact ◽  
Taganrog Bay

The distribution and behavior of certain of trace elements in sea water is greatly affected by both physical, chemical and hydrometeorological conditions that are showed in the scientific works of prof. Yu.A. Fedorov with coauthors (1999-2015). Due to the shallow waters last factor is one of the dominant, during the different wind situation changes significantly the dynamics of water masses and interaction in the system “water – suspended matter – bottom sediments”.Therefore, the study of the behavior of the total iron in the water of the sea at different wind situation is relevant. The content of dissolved iron forms migration in The Sea of Azov water (open area) varies from 0.017 to 0.21 mg /dm3 (mean 0.053 mg /dm3) and in Taganrog Bay from 0.035 to 0.58 mg /dm3 (mean 0.11 mg /dm3) and it is not depending on weather conditions.The reduction in the overall iron concentration in the direction of the Taganrog Bay → The Sea of Azov (open area) is observed on average more than twice. The dissolved iron content exceeding TLV levels and their frequency of occurrence in the estuary, respectively, were higher compared with The Sea of Azov (open area).There is an increase in the overall iron concentration in the water of the Azov Sea on average 1.5 times during the storm conditions, due to the destruction of the structure of the upper layer and resuspension of bottom sediments, intensifying the transition of iron compounds in the solution.

scholarly journals Iron-Oxidizing Bacteria Are Associated with Ferric Hydroxide Precipitates (Fe-Plaque) on the Roots of Wetland Plants

1999 ◽  
Vol 65 (6) ◽  
pp. 2758-2761 ◽  
Author(s):  
David Emerson ◽  
Johanna V. Weiss ◽  
J. Patrick Megonigal
Keyword(s):  
Ferric Hydroxide ◽  
Root Systems ◽  
Wetland Plants ◽  
Positive Correlation ◽  
Cell Numbers ◽  
Iron Oxidizing Bacteria ◽  
Soil Solutions ◽  
Fe Plaque ◽  
Ph Range

ABSTRACT The presence of Fe-oxidizing bacteria in the rhizosphere of four different species of wetland plants was investigated in a diverse wetland environment that had Fe(II) concentrations ranging from tens to hundreds of micromoles per liter and a pH range of 3.5 to 6.8. Enrichments for neutrophilic, putatively lithotrophic Fe-oxidizing bacteria were successful on roots from all four species; acidophilic Fe-oxidizing bacteria were enriched only on roots from plants whose root systems were exposed to soil solutions with a pH of <4. InSagittaria australis there was a positive correlation (P < 0.01) between cell numbers and the total amount of Fe present; the same correlation was not found for Leersia oryzoides. These results present the first evidence for culturable Fe-oxidizing bacteria associated with Fe-plaque in the rhizosphere.

Quantitation of reticuloendothelial iron kinetics in humans

1984 ◽  
Vol 247 (5) ◽  
pp. R842-R849 ◽  
Author(s):  
M. Stefanelli ◽  
D. P. Bentley ◽  
I. Cavill ◽  
H. P. Roeser
Keyword(s):  
Binding Capacity ◽  
Iron Concentration ◽  
Transferrin Saturation ◽  
Ferric Hydroxide ◽  
Equal Proportion ◽  
Dual Isotope ◽  
Plasma Iron ◽  
Storage Pool ◽  
Iron Kinetics

Reticuloendothelial iron kinetics were investigated in a simultaneous dual-isotope study in 10 healthy adult subjects in whom 55Fe-ferric hydroxide phosphate colloid was used to label the reticuloendothelial iron pools, and 59Fe-transferrin was used to define plasma iron kinetics. The simultaneous clearance of 55Fe and 59Fe from plasma and the uptake of each into red blood cells were measured over 14 days. The 55Fe-colloid was cleared almost immediately, and its iron was rapidly released to bind to plasma transferrin. Red cell incorporation of 55Fe was, however, much slower than that of 59Fe bound to transferrin in vitro. The data were analyzed by a new model of reticuloendothelial iron metabolism that contained two reticuloendothelial iron pools; one had a rapid turnover and donated iron to transferrin, and the other, a storage pool, had a slower turnover. The transit pool contained a mean of 164 mumol iron with little variation between subjects, whereas the storage pool was somewhat larger (mean 873 mumol iron) and showed more marked variation between subjects. In general an equal proportion of the iron leaving the transit pool went to transferrin and to the storage pool. The distribution between the two routes did not appear to be related either to plasma iron concentration, latent iron-binding capacity, or transferrin saturation.

Fecal total iron concentration is inversely associated with fecalLactobacillusin preschool children

2017 ◽  
Vol 32 (8) ◽  
pp. 1475-1479 ◽  
Author(s):  
Sasank Kalipatnapu ◽  
Sivaraman Kuppuswamy ◽  
Giriprasad Venugopal ◽  
Venkatesh Kaliaperumal ◽  
Balamurugan Ramadass
Keyword(s):  
Preschool Children ◽  
Iron Concentration ◽  
Total Iron ◽  
Total Iron Concentration

The Effect of Total Iron Concentration and Iron Speciation on the Rate of Ferrous Iron Oxidation Kinetics of Leptospirillum ferriphilum in Continuous Tank Systems

2007 ◽  
Vol 20-21 ◽  
pp. 447-451 ◽  
Author(s):  
Jochen Petersen ◽  
Tunde Victor Ojumu
Keyword(s):  
Oxidation Kinetics ◽  
Ferrous Iron ◽  
Ferric Iron ◽  
Iron Oxidation ◽  
Iron Concentration ◽  
Total Iron ◽  
Ferrous Iron Oxidation ◽  
Utilisation Rate ◽  
Kinetics Of ◽  
Total Iron Concentration

In this study the results from a systematic study of the oxidation kinetics of Leptospirillum ferriphilum in continuous culture at total iron concentrations ranging from 2 to12 g/L are reported. In all experiments the steady-state concentrations of ferrous iron were small and comparable, and at least 97% of was as ferric. Surprisingly, the specific ferrous iron utilisation rate decreased with increasing total iron concentration, while yield coefficients increased. It was noted that the biomass concentration in the reactor (as measured by both CO2 uptake rate and cell counts) dramatically increased with increasing total iron concentrations, whereas it stayed more or less the same over a wide range of dilution rates at a given total iron concentration. The experimental data was re-analysed in terms of ferrous iron kinetics using Monod kinetics with a ferric inhibition term. The results confirm that the maximum specific iron utilisation rate is itself a function of ferric iron concentration, declining with increasing concentration. It thus appears that high concentrations of ferric iron stimulate microbial growth while at the same time inhibiting the rate of ferrous iron oxidation. It is postulated that these phenomena are related, i.e. that more growth occurs to reduce the load on the individual cell, possibly by sharing some metabolic functions.

scholarly journals The number fraction of iron-containing particles affects OH, HO<sub>2</sub> and H<sub>2</sub>O<sub>2</sub> budgets in the atmospheric aqueous phase

2021 ◽  
Author(s):  
Amina Khaled ◽  
Minghui Zhang ◽  
Barbara Ervens
Keyword(s):  
Particulate Matter ◽  
Aqueous Phase ◽  
Aerosol Particles ◽  
Iron Concentration ◽  
Transition Metal Ions ◽  
Total Iron ◽  
Chemical Mechanism ◽  
Cloud Droplets ◽  
Iron Distribution ◽  
Total Iron Concentration

Abstract. Reactive oxygen species (ROS), such as OH, HO2, H2O2 affect the oxidation capacity of the atmosphere and cause adverse health effects of particulate matter. The role of transition metal ions (TMIs) in impacting the ROS concentrations and conversions in the atmospheric aqueous phase has been recognized for a long time. Model studies usually assume that the total TMI concentration as measured in bulk aerosol or cloud water samples is distributed equally across all particles or droplets. This assumption is contrary to single-particle measurements that have shown that only a small number fraction of particles contain iron and other TMIs (FN,Fe < 100 %) which implies that also not all cloud droplets contain TMIs. In the current study, we apply a box model with an explicit multiphase chemical mechanism to simulate ROS formation and cycling in (i) aqueous aerosol particles and (ii) cloud droplets. Model simulations are performed for the range of 1 % ≤ FN,Fe ≤ 100 % for constant pH values of 3, 4.5 and 6 and constant total iron concentration (10 or 50 . Model results are compared for two sets of simulations with FN,Fe < 100 % (FeN < 100) and 100 % (FeBulk). We find largest differences between model results in OH and HO2/O2− concentrations at pH = 6. Under these conditions, HO2 is subsaturated in the aqueous phase because of its high effective Henry's law constant and the fast chemical loss reactions of the O2− radical anion. As the main reduction of process of Fe(III) is its reaction with HO2/O2−, we show that the HO2 subsaturation leads to predicted Fe(II)/Fe(total) ratios for FN,Fe < 100 % that are lower by a factor of ≤ 2 as compared to bulk model approaches. This trend is largely independent of the total iron concentration, as both chemical source and sink rates of HO2/O2− scale with the iron concentration. The chemical radical (OH, HO2) loss in particles is usually compensated by its uptake from the gas phase. We compare model-derived reactive uptake parameters γ(OH) and γ(HO2) for the full range of FN,Fe. While γ(OH) is not affected by the iron distribution, the calculated γ(HO2) range from 0.0004 to 0.03 for FN,Fe = 1 % and 100 %, respectively. Implications of these findings are discussed for the application of lab-derived γ(HO2) in models to present reactive HO2 uptake on aerosols. As the oxidant budget in aerosol particles and cloud droplets is related to the oxidative potential, we also conclude that the iron distribution FN,Fe should be taken into account to estimate the ROS concentrations and health impacts of particulate matter that might be overestimated by bulk sampling and model approaches. Our study suggests that the number concentration of iron-containing particles may be more important than the total iron mass concentration in determining ROS budgets and uptake rates in cloud and aerosol water.

Groundwater Iron Assessment and Consumption by Women in Rural Northwestern Bangladesh

2012 ◽  
Vol 82 (1) ◽  
pp. 5-14 ◽  
Author(s):  
D. Merrill ◽  
A. Shamim ◽  
Ali ◽  
Jahan ◽  
B. Labrique ◽  
...  
Keyword(s):  
Iron Content ◽  
Iron Concentration ◽  
Total Iron ◽  
Reproductive Age ◽  
Rural Setting ◽  
Iron Intake ◽  
High Iron Content ◽  
Northwestern Bangladesh ◽  
Local Water ◽  
The Impact

In Bangladesh, approximately 97 % of the rural population uses groundwater as a drinking source. In many areas of the country this water is known to have elevated levels of iron. The contribution to iron intake that this exposure provides, and the impact on health, are unknown. In the pre- and post-monsoon seasons of 2008, we measured iron content of household tube well water, explored local water collection methods, and estimated iron intake through consumption of groundwater for 276 women of reproductive age in a rural setting in northwestern Bangladesh. Groundwater samples were analyzed for total iron (mg/L), arsenic (category of µg/L), pH, temperature (oC), and oxidation-reduction potential (Eh). Participants drank [mean (SD); 2.7 (0.8) L] of water per day, all of which was collected from domestic tube wells. Total iron concentration in groundwater was high, [median (IQR) 16.3 (6.9, 28.2) mg/L], and variable throughout the area. Using this value, estimated daily iron intake [median (IQR)] was 41.1 (16.0, 71.0) mg from drinking water alone. The amount of water consumed was unrelated to its iron concentration (r = - 0.06; p = 0.33) despite potentially unpleasant organoleptic qualities of high iron content in water. Groundwater contributes substantially to daily iron intake of rural Bangladeshi women and currently represents an under-assessed potential source of dietary iron.

Removal of Arsenic from Rural Water Supplies

1982 ◽  
Vol 17 (1) ◽  
pp. 75-82
Author(s):  
Gerald D. Lutwick
Keyword(s):  
Contact Time ◽  
Ferric Iron ◽  
Ferric Hydroxide ◽  
Maximum Flow ◽  
Total Arsenic ◽  
Water Supplies ◽  
Rural Water ◽  
Ph Range ◽  
Removal Of Arsenic ◽  
Insoluble Salt

Abstract Diatomite impregnated with ferric hydroxide has been field tested for removal of arsenic from rural domestic waters. The waters tested covered the pH range of 6.5 to 8.2 and the total arsenic concentrations of 0.04 to 0.58 mg/L. As the water passes through the bed of ferric hydroxide ferric arsenate is formed, an insoluble salt. Arsenic is present in ground waters as arsenite and arsenate. Arsenite is removed from water supplies by oxidizing the arsenite to arsenate with hypochlorite before passage through the bed of ferric hydroxide. The units contain a bed at least 48 cm deep and 25 cm in diameter. The diatomite is 10 to 50 mesh and contains 3 to 4% ferric iron as the hydroxide. The unit was designed for a minimum contact time of one minute allowing a maximum flow rate of 36 litres per minute.

CHEMICAL COMPONENTS IN RIME ON MT. MORIYOSHI IN NORTHERN JAPAN

2005 ◽  
Vol 15 (03n04) ◽  
pp. 211-219 ◽  
Author(s):  
KATSUMI SAITOH ◽  
HITOSHI KODAMA ◽  
KOICHIRO SERA ◽  
KEIJI YOSHIMURA ◽  
OSAMU NAGAFUCHI
Keyword(s):  
Ionic Species ◽  
Spherical Particles ◽  
Chemical Components ◽  
Pixe Analysis ◽  
Edx Analysis ◽  
Surface Snow ◽  
Ph Range ◽  
Northeast Asian ◽  
Fresh Surface ◽  
Snow Samples

In order to shed light on the long-range transport of atmospheric pollutants in the Northeast Asian regions, we studied the chemical components in rime and fresh surface snow on Mt. Moriyoshi (altitude: 1454 m), located on the Sea of Japan side of northern Honshu, Japan, near Northwest China and Southwest Russia. Rime and fresh surface snow samples were collected at Juhyou-Daira (near the summit; altitude: 1200 m) in February 2004. The pH range of rime samples was 4.2 – 4.9, and the electric conductivity (EC) range was 52 – 282 μS/cm. On the other hand, the pH range of snow samples was 4.5 – 4.9, and the EC range was 17 – 77 μS/cm. The elemental compositions, ionic species and particle shapes of these samples were determined and/or observed by PIXE, ion chromatography and SEM-EDX analysis. PIXE analysis of the rime and snow samples revealed 24 elements, of which Na , Mg , Al , Si , K , Ca , Ti and Fe were found to be the major components. Comparing the determined values of rime and snow sample elements, rime samples were several times to several dozen times higher than snow samples for almost all the elements. For determined values of ionic species, rime samples were several times to several dozen times higher than snow samples. With the aid of SEM-EDX analysis, many small silicon-rich spherical particles were observed in the rime samples. Small silicon-rich spherical particles were also found in the snow samples. The existent forms of chemical components in rime will be an important factor when we consider the origin of air pollutants transported over long distances in the Northeast Asian regions.

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