Effect Of Ferric Ions Research Articles

Interactions of Iron and Viscoelastic Surfactants: A New Formation-Damage Mechanism

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 112465, "Interactions of Iron and Viscoelastic Surfactants: A New Formation-Damage Mechanism," by A.R. Al-Nakhli, SPE, Saudi Aramco; H.A. Nasr-El-Din, SPE, Texas A&M U.; and A.A. Al-Baiyat, King Fahd U. of Petroleum and Minerals, prepared for the 2008 SPE International Symposium and Exhibition on Formation Damage Control, Lafayette, Louisiana, 13–15 February. The paper has not been peer reviewed. Viscoelastic-surfactant (VES)-based acids have been used extensively in the last few years in matrix- and acid-fracturing treatments. The results from one treatment were below expectations. Analysis of the live acid used indicated that this acid contained nearly 10 000 mg/L total iron. This study was conducted to provide a better understanding of interactions between iron and VESs. Introduction The existence of iron in the stimulation process is almost a given in every step of the treatment. Therefore, the interaction of iron with acid additives should be examined carefully. Acid additives that were introduced recently are VESs. These surfactants (amphoteric, anionic, or cationic, or combinations of these types) are used to divert the acid in carbonate formations. Amphoteric and cationic surfactants contain function groups that can interact with iron. The full-length paper examines the effect of ferric ion (Fe3+) on amphoteric- and cationic-based VESs. When stimulating a carbonate, the acid, mostly hydrochloric acid (HCl), will react with calcium carbonate (CaCO3) to produce calcium chloride (CaCl2) and increase the pH value. The increase in pH value will trans-form the special micellars into long rod-shaped ones. This transformation is accompanied by a significant increase in fluid viscosity. It is very important to measure the effect of Fe3+ on the viscosity of VES solutions because Fe3+ is expected to be significant during well treatment; iron concentration could be as high as 100 000 mg/L. Also, it is important to study the formation of various ferric species with VESs. The presence of iron can affect the behavior and function of VES-based fluids adversely. Therefore, the objective of the present study is to examine potential interactions between Fe3+ and two categories of VES that have been used in the field: amphoteric and cationic VES. Sources of Fe3+ During acidizing treatments, the acid can be contaminated with iron com-pounds at all stages. Rust in storage tanks and mixing tanks can be dissolved by the acid and produce a mixture of iron(II) and Fe3+. However, dissolved oxygen in the acid will oxidize iron(II) to Fe3+. Large amounts of iron in live acids can result during acid injection as the acid dissolves mill scale in new tubing or corrosion products. Iron content was measured in an acid solution at four different points in the acidizing process. Iron content at the wellhead varied from 200 to 3500 mg/L, and the returning acid showed iron concentrations of 9000 to 100 000 mg/L during cleanup treatments of new wells. Moreover, thin deposits of iron sulfide scale on tubing can result in large quantities of iron(II) in solution during an acid treatment. Also, the formation brine may have iron in solution.

Effect of Ferric Ions on the Mechanical Strength of Marine Mussel Adhesive Proteins

Mussel adhesive protein (MAP) is expected to be used as a new bioadhesive. However, the mechanical properties of MAP have not been reported, despite the potential importance of MAP in medical applications. The study aims to estimate the mechanical strength of MAP, and describe the influence of ferric ions present in MAP on the mechanical strength. Fe3+ incorporated in MAP is regarded as having an important role in the mechanical properties. Mussels were classified into two groups in order to compare the effect of Fe3+ on both the tensile and peel properties of MAP. One group was exposed to artificial seawater with a high concentration of ferric ions, and the other group is exposed to natural seawater as a control. The results revealed that the deterioration of the adhesive strength over time was different between the two groups, although significant differences in the tensile properties were not observed. While the adhesive strength in the control group decreased with elapsed time, it was increased for the iron-enriched group over the first 17 days. This suggested that ferric ions may improve the magnitude of the adhesive strength for MAP.

One‐pot synthesis of a polysaccharide‐based graft copolymer with an efficient redox pair (Fe2+/BrO3−)

AbstractA graft copolymer based on a polysaccharide (sodium salt of carboxymethylcellulose) and a vinyl monomer (acrylamide) has been synthesized in a nitrogen atmosphere, and its reaction conditions have been optimized for a better yield with ferrous sulfate and potassium bromate as a redox initiator. The effects of ferrous ion, bromate ion, hydrogen ion, sodium carboxymethylcellulose, and acrylamide along with the reaction time and temperature have been studied through the determination of the grafting parameters: the grafting ratio, add‐on, conversion, efficiency, homopolymer, and rate of grafting. The maximum yield has been found to occur when the acrylamide concentration is 8.0 × 10−2 mol/dm3, whereas the maximum conversion occurs at a minimum concentration of acrylamide, that is, at 3.0 × 10−2 mol/dm3. The grafting parameters have been found to increase with an increasing concentration of the redox initiator (Fe2+, from 2.0 × 10−3 to 10.0 × 10−3 mol/dm3; BrO, from 2.2 × 10−3 to 4.0 × 10−3 mol/dm3). The maximum efficiency occurs with a reaction time of 210 min. The rate of grafting has been found to be maximum up to 60 min; after that, it decreases rapidly. In this article, it is shown that the hydrogen ion leads to a very clear decrease in the grafting parameters as its concentration increases from 2.1 × 10−3 to 11.3 × 10−3 mol/dm3. Grafted gum and ungrafted gum have been characterized with Fourier transform infrared spectroscopy and thermogravimetric analysis. A probable mechanism has been suggested for graft copolymerization. It has been observed that the graft copolymer is thermally more stable than the parent backbone. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of ferrous ion on photo heterotrophic hydrogen production by Rhodobacter sphaeroides

The effect of ferrous ion (0–3.2 mg/l) on photo heterotrophic hydrogen production was studied in batch culture using sodium lactate as substrate. The results showed that hydrogen production by Rhodobacter sphaeroides was significantly suppressed when Fe 2 + was limited. Hydrogen production increased linearly with an increase in Fe 2 + concentration in the range of 0–1.6 mg/l; reaching a maximum at 2.4 mg/l. When hydrogen production was suppressed in the above medium, a pH increase to 8.9 was observed, and the ratio of lactate utilized to total organic carbon removal was found to be increased, indicating that more soluble organic products were produced. Under the Fe 2 + limited conditions, ferrous iron was shown to have a greater effect on hydrogen production by Rb. sphaeroides than that by the anaerobic heterotrophic bacterium Clostridium butyricum.

The effect of ferric ions on the conductivity of various types of polymer cation exchange membranes

Recently, rejuvenated interest to fuel cells has posed a number of problems regarding the polymer electrolyte membrane properties and their behaviour in different electrolyte solutions. This work was dedicated to study the conductivity of H+-, Fe3+- and mixed H+/Fe3+-forms of cation exchange membranes Neosepta CMS, Nafion 112, 115 and 117 and Selemion HSF under conditions similar to these in the Fe3+/Fe2+–H2/H+ fuel cell in the range of current densities 0–90 mA/cm2. It was found that the conductivities of these membranes in 1.09 M H2SO4 solution decrease in the following order: Selemion HSF › Nafion 117 ≈ Nafion 115 ≈ Neosepta CMS › Nafion 112. Conductivities of perfluorinated membranes were discussed in terms of Hsu and Gierke percolation theory [20]. The Fe3+-forms of Nafion membranes studied displayed a monotonous decline in the resistance when current increased, which is a manifestation of gradual conversion of the Fe3+-form into H+-form of these membranes. Unlike the Nafion membranes, the Fe3+-forms of Neosepta CMS and Selemion HSF membranes exhibited a sharp jump of resistance at relatively high current densities (more than 70 mA/cm2) that is most probably a result of concentration polarization.

Effect of ferrous ion on the biological activity in a UASB reactor: Mathematical modeling and verification

The effect of ferrous ion on the biological activity in a upflow anaerobic sludge blanket (UASB) reactor was studied. A mathematical model was developed and validated in order to simulate the dynamic behavior of a UASB reactor. This model took into consideration of all the biological and physicochemical reactions. The model was able to simulate the accumulation of iron in the sludge bed and its effect on the biological activity of the anaerobic sludge. A significant increase in the maximum uptake rate of methanogens and acidogens was revealed when iron was supplemented to the UASB reactor. The addition of ferrous iron induced a stable and excellent COD conversion rate. The model can be a useful tool for the prediction of process performance in the future and can be used to assist in the operation of biogas plants. The ferrous ion addition proved to enhance the biological activity of UASB sludge. Thus, the model can be used for the design of treatment plants that will take advantage of the benefits of iron addition.

Reduced Adsorption of Ametryn in Clay, Humic Acid, and Soil by Interaction with Ferric Ion Under Fenton Treatment Conditions

Previous work in our laboratory indicated a weak interaction between ferric ion and several triazine/triazinone herbicides during a Fenton treatment process, and the intensity of the interaction was calculated. To further support the existence of this weak interaction, the adsorption of ametryn, a triazine herbicide, was investigated in kaolinite clay, humic acid, and soil under pseudo-Fenton conditions. At a low addition rate of ferric ion, the adsorption of ametryn in clay, humic acid, and soil was enhanced due to the decreased pH resulting from the hydrolysis of ferric ion. But the pH effect was totally neutralized and the adsorption of ametryn was significantly reduced by further addition of ferric ion, demonstrating the existence of the weak interaction between ametryn and ferric acid. Further study showed that the adsorption-reduction effect of ferric ion existed not only with ametryn but also with several other triazine/triazinone herbicides. This weak interaction may accelerate the desorption process during the remediation of triazine/triazinone herbicide-contaminated soil using a Fenton/Fenton-like treatment, but it may also impede the degradation of these herbicides.

Electrochemical Behavior of Hot-Rolled 304 Stainless Steel during Chemical Pickling in HCl-Based Electrolytes

The mechanism and kinetics of chemical pickling of hot-rolled 304 stainless steel oxidized at high temperatures was investigated in HCl-based electrolytes with weight loss, corrosion potential, and electrochemical impedance spectroscopy (EIS) measurements. Corrosion products were characterized with scanning electron microscopy–energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray photoelectron spectroscopy (XPS). The mechanism of chemical pickling in HCl-based electrolytes is associated with anodic brightening. A highly ionically conductive corrosion product layer covering the brightened surface ensures a high corrosion rate of the underlying stainless steel. The addition of ferric ions to HCl-based electrolytes significantly enhances the corrosion rate. On the contrary, the influence of HCl becomes less important because it is highly concentrated, resulting in a brightening of the stainless steel surface. The effect of ferrous ions on the corrosion rate is negligible. The charge-transfer resistance of hot-rolled stainless steel decreases with pickling time due to the progressive removal of oxide layers.

Effects of ferrous ions on the reductive dechlorination of trichloroethylene by zero-valent iron

The surface characteristics of zero-valent iron (ZVI) and the efficiency of reductive dechlorination of trichloroethylene (TCE) in the presence of ferrous ions were studied. The experimental results indicated that the acid-washing of a metallic iron sample enhanced the efficiency of TCE degradation by ZVI. This occurred because acid-washing changed the conformation of oxides on the surface of iron from maghemite (γ-Fe 2O 3) to the more hydrated goethite (α-FeOOH), as was confirmed by XPS analysis. However, when ferrous ions were simultaneous with TCE in water, the TCE degradation rate decreased as the concentration of ferrous ion increased. This was due to the formation of passive precipitates of ferrous hydroxide, including maghemite and magnetite (Fe 3O 4), that coated on the surface of acid-washed ZVI, which as a result inhibited the electron transfer and catalytic hydrogenation mechanisms. On the other hand, in an Fe 0-TCE system without the acid-washing pretreatment of ZVI, ferrous ions were adsorbed into the maghemite lattice which was then converted to semiconductive magnetite. Thus, the electrons were transferred from the iron surface and passed through the precipitates, allowing for the reductive dechlorination of TCE.

Effects of ferric ion on bioleaching of heavy metals from contaminated sediment

Bioleaching is one of the promising procedures for removal of heavy metals from contaminated sediments. The advantages of this biotechnology are that it is easy, efficient, less costly and friendly to the environment. However, the principal disadvantage of this process is its slow kinetics in metal solubilization, which may limit practical application of the bioleaching process. In order to enhance the rate and efficiency of metal solubilization, the ferric ion was used as a catalytic agent in the bioleaching process. It was found that the sediment pH apparently decreased in the bioleaching after addition of ferric ion. The metal solubilization increased quickly after the addition of ferric ion. The rate of metal solubilization was enhanced by the addition of ferric ion, especially for Cr and Pb. An increase in the amount of ferric ion added increased the final efficiency of metal solubilization. The highest final efficiency of metal solubilization was obtained in the bioleaching with 1 g/L of ferric ion. Besides, the growth of sulfur-oxidizing bacteria was not affected by addition of ferric ion in the bioleaching. It was concluded that the kinetics of metal solubilization were enhanced by addition of ferric ion in the bioleaching process.

Fe 2+ decreases the taurine-induced Cl − current in acutely dissociated rat hippocampal neurons

The effects of ferrous ions (Fe 2+) on taurine-induced Cl − current ( I tau) recorded from single neurons, which was freshly isolated from the rat hippocampal CA1 area, were studied with conventional whole-cell recording under voltage-clamp conditions. Using standard pharmacological approaches, we found that the currents gated by concentrations of taurine (≤10 mM), which existed in about 90% of the hippocampal neurons tested, were predominantly mediated by strychnine-sensitive glycine receptors. When co-applied with taurine, Fe 2+ effectively depressed I tau in a concentration-dependent manner, with an IC 50 of 3.76 mM and Hill coefficient of 1.01, while preincubation with 1 mM Fe 2+ alone did not affect the following membrane currents elicited by taurine. The result suggests that resting taurine-gated channels are insensitive to Fe 2+. Since internal cell dialysis with 3 mM Fe 2+ failed to modify I tau, it was deduced that the site of action of Fe 2+ is extracellular. Furthermore, the Lineweaver–Burke double reciprocal plot of normalized response to taurine against the concentration of taurine illustrated that the depression of I tau was noncompetitive, therefore Fe 2+ may act on the glycine receptor–chloride ionophore complex at a site distinct from where taurine binds. Various concentrations of Fe 2+ ranging from 0.1 to 20 mM depressed I tau and this extracellular depression was independent of membrane voltage. These results indicate that Fe 2+ decreases I tau in acutely dissociated rat hippocampal neurons and the inhibition of glycine receptors by Fe 2+ might be one possible approach through which Fe 2+ induces seizures.

Surface studies of a chalcogenide glass ferric ion‐selective electrode Part 1: Influence of ferric and hydroxide ions on interfacial kinetics

AbstractX‐ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and in situ electrochemical impedance spectroscopy (EIS) have been used to characterize the interfacial chemistry of the chalcogenide glass ferric (FeIII) ion‐selective electrode (ISE). The effects of ferric ions (Fe3+) and hydroxide ions (OH−) on the FeIII ISE have been studied and a mechanism for their action is proposed. It has been shown that an elevated hydroxide ion concentration causes the chalcogenide glass FeIII ISE to experience accelerated corrosion. In particular, XPS detected the formation of various antimony and iron hydroxide/oxide species, whereas SIMS and SEM revealed extensive dissolution of germanium selenide from the chalcogenide glass in the presence of OH−. The EIS measurements demonstrated that the rate of charge transfer is facilitated under extreme alkaline conditions, and this is internally consistent with the XPS/SIMS results. By contrast, EIS and XPS aging studies in ferric ion solution revealed a mild passivation film symbolic of an oxide layer. Extended aging of the chalcogenide glass membrane demonstrated a decrease in the charge transfer impedance, indicative of a breakdown in the passive layer properties. It has been shown that a charge transfer reaction occurs between Fe3+ and Ge2+ selenide sites in the membrane and that the rate of reaction is strongly dependent on temperature. Copyright © 2002 John Wiley & Sons, Ltd.

Acid Refining of Synthesised Alloys Within the Quaternary System Fe–Si–Ca–AI: Effect of Ferric Ions

A systematic study of synthesis of different chemical composition of alloys within the quaternary Fe–Si–Ca–Al system, versus acid leaching refining using HCl with or without FeCl3 has been undertaken. Such study has the aim of achieving an adequate structural composition of Fe–Si alloys, in order to obtain high purity and fine particle size silicon by acid leaching, at more reduced costs. The experimental results show that an adequate control of Fe/Al and Si/Ca concentration ratios can hinder the formation of tetragonal and orthorhombic FeSi2 phases, and consequently promotes a successful refining of ferro-silicon alloys. The presence of ferric ion influences on a distinct way the rate of removal of Al–Fe–Si and Fe–Al–Si–Ca phases, increasing the first and decreasing the second one. The suitable starting composition which could give the expected results must be the following: 92–94% Si; 3–3.5% Fe; 3.5–4% Al and Ca ≤ 0.5%.

Enhancement of chalcopyrite leaching by ferrous ions in acidic ferric sulfate solutions

The effects of ferrous ions on chalcopyrite oxidation with ferric ions in 0.1 mol dm −3 sulfuric acid solutions were investigated by leaching experiments at 303 K in nitrogen. With high cupric ion concentrations, the chalcopyrite oxidation was enhanced by high concentrations of ferrous ions and copper extraction was mainly controlled by the concentration ratio of ferrous to ferric ions or the redox potential of solutions. Ferrous ions, however, suppressed the chalcopyrite oxidation when cupric ion concentrations were low. A reaction model, which involves chalcopyrite reduction to intermediate Cu 2S by ferrous ions and oxidation of the Cu 2S by ferric ions, was proposed to interpret the results.

Acid Refining of Synthesised Alloys Within the Quaternary System Fe-Si-Ca-AI: Effect of Ferric Ions

A systematic study of synthesis of different chemical composition of alloys within the quaternary Fe-Si-Ca-AI system, versus acid leaching refining using HCI with or without FeCl3 has been undertaken. Such study has the aim of achieving an adequate structural composition of Fe-Si alloys, in order to obtain high purity and fine panicle size silicon by acid leaching, at more reduced costs. The experimental results show that an adequate control of Fe/Al and Si/Ca concentration ratios can hinder the formation of tetragonal and orthorhombic FeSl2 phases, and consequently promotes a successful refining of ferro-silicon alloys. The presence of ferric ion influences on a distinct way the rate of removal of Al-Fe-Si and Fe-Al-Si-Ca phases, increasing the first and decreasing the second one. The suitable starting composition which could give the expected results must be the following: 92-94% Si; 3-3.5% Fe; 3.5-4% Al and Ca < 0.5%.

The role of ( E)-4-hydroxy-2-nonenal in platelet activation by low density lipoprotein and iron

( E)-4-Hydroxy-2-nonenal (HNE) is a highly reactive product of the oxidation of low density lipoprotein (LDL) which increases the platelet aggregation response to various agonists. HNE formation was increased during the enhanced platelet aggregation to thrombin, ADP, A23187 and epinephrine in the presence of LDL. The increase in platelet aggregation and HNE formation by LDL was inhibited by superoxide dismutase and catalase, suggesting superoxide and hydrogen peroxide produced by platelets during aggregation may be at least partly responsible. The responsiveness of platelets to LDL and the accompanying HNE formation was increased further in the presence of ferrous ion. The effect of ferrous ion on both platelet responses and HNE formation was decreased by superoxide dismutase, catalase and the antioxidants dipyridamole and probucol implicating platelet-derived free radicals. Ferrous ion caused an increase in the release of arachidonic acid from platelet membrane phospholipids in the presence of LDL which was probably caused by increased HNE production. The results suggest iron could increase platelet reactivity at sites of vascular injury by increasing HNE formation and promote the development of atherosclerotic lesions.

Effect of ferrous ion in solution on the formation of anodic oxide film on iron

The effect of Fe 2+ ion in the solution on the anodic formation of the passive oxide film onto iron was investigated by the ellipsometric trace of the film growth in a borate solution at pH 8.4. In addition to a compact inner passive film, formed by initial direct oxidation, the Fe 2+ ion in the solution is oxidized to build up an outer hydrous layer at the latter stage. The inner layer behaves similarly as the usual passive film, in which the film growth follows the ionic migration mechanism under high electric field. The outer layer growth may, however, be determined by a surface reaction between the film and the electrolyte solution, i.e., the growth rate is independent of potential and a linear function of the Fe 2+ ion concentration in the solution.

Grafting polymerization of acrylic acid onto preirradiated polypropylene fabric

Acrylic acid (AAc) was grafted onto polypropylene (PP) fabric by a preirradiation method using a Co-60 gamma ray. The effect of absorbed dose, AAc concentration, reaction temperature, reaction time, storage time, as well as the effect of ferrous ion and sulfuric acid on the degree of grafting were determined. It has been shown that the synergistic effect of sulfuric acid with the ferrous sulfate can not only increase the grafting yield, but also decrease the apparent activation energy for the grafting. It leads to the possibility of getting a particular grafting yield at a lower absorbed dose. In this experiment, It has also been shown that the grafting activity of preirradiated PP fabric in AAc aqueous solution could be well kept at room temperature for a long period.

The surface and solution chemistry of pyrite flotation with xanthate in the presence of iron ions

The effects of the surface and solution chemistry of the Fe(II) and Fe(III) ions on the flotation of both ore- and coal-pyrite with xanthate have been systematically investigated based on flotation results, zeta potential measurements and thermodynamic calculations. It was found that the presence of ferrous and ferric ions in solution significantly depresses ore-pyrite flotation in the pH range of 6–9.5. The effect of ferrous ions is stronger than that of ferric ions. Coal pyrite was found to be nonfloatable above pH 6 due to the large amounts of ferrous ions resulted from pyrite oxidation. The results of thermodynamic calculations have been found to be in good agreement with the experimental results, indicating that the formation of ferric hydroxyl xanthate compounds are responsible for the reduced floatabilities of pyrites when pH is greater than 6.

Effect of Ferrous Ion on Amino Acid Metabolism in Mildiomycin Production by Streptoverticillium rimofaeiens.

The physiological features of the mildiomycin production by Streptoverticillium rimofaciens were examined in iron-sufficient and -deficient media. Activities of NADP-linked glutamate dehydrogenase (GDH) and aspartate aminotransferase (AAT) were markedly enhanced by the addition of 10 micrograms/ml of ferrous ion into culture. Ammonium nitrogen assimilation increased with the increase in mildiomycin production. These indicate that ferrous ion contributes the supply of amino acids as a precursor of mildiomycin production. In the iron-sufficient medium, glutamate, aspartate, serine and arginine in cells were 2 to 10-fold to those in the iron-deficient medium. The major amino acid excreted from cells was arginine in the iron-sufficient culture, while in the iron-deficient culture, valine. Change in the amino acid profile by addition of ferrous ion was useful for mildiomycin biosynthesis, in which ferrous ion played a leading role in amino acid metabolism.