Concentrations Of Metal Cations Research Articles

Cellular Automata Study of the Combined Effects of Passive Film Breakdown and Repassivation on Metastable Pits on Sputtered Nanocrystalline Stainless Steel

The growth of metastable pits on sputtered nanocrystalline stainless steel (NCss) was simulated by a cellular automata technology. Pit morphologies, passive film breakdown, and the metal cation concentration inside the metastable pit during its growth were analyzed. The combined effects of passive film breakdown and repassivation hindered metastable pit growth on the NCss, even though their isolated effects may vary significantly. The calculated values of the critical pitting temperature are shown to be statistically distributed because of the difficulty of passive film breakdown, repassivation, and the metastable/stable pitting transition.

Localized Corrosion: Passive Film Breakdown vs Pit Growth Stability: Part V. Validation of a New Framework for Pit Growth Stability Using One-Dimensional Artificial Pit Electrodes

Experimental evidence is provided to support the validity of a new framework for pit growth stability established in previous papers in this series. Downward potential scans from the diffusion-controlled condition were performed on SS316L one-dimensional (1D) artificial pit electrodes in 0.6 M NaCl. The variation of the critical pit surface potential for salt film formation with pit depth was in agreement with the theoretical prediction of the new framework. Using pits of different depths, the maximum pit dissolution current density, idiss,max, was obtained as a function of maximum pit surface potential, Emax, at fixed pit surface metal cation concentrations, Csurf, equal to the saturation concentration, Csat, and 70%Csat. The apparent Tafel slope of the pit dissolution kinetics determined using the downward potential scan of a 1D pit in the charge-transfer-controlled region, where Csurf changes continuously during the scan, was smaller than the Tafel slope for idiss,max(Emax) at a fixed Csurf, indicating that Csurf is a key parameter for pit dissolution. The critical concentration for pit stability/repassivation was found to be approximately 43% of Csat. Charge-transfer-controlled 1D pit growth was shown to be a transient state, which will spontaneously transition to diffusion-controlled growth in accordance with the predictions of the new framework.

Concentrations of Heavy Metal Cations and a Health Risk Assessment of Sediments and River Surface Water: A Case Study from a Serbian Mine

Concentrations of Heavy Metal Cations and a Health Risk Assessment of Sediments and River Surface Water: A Case Study from a Serbian Mine

STUDY OF Cu(II) ADSORPTION BY BENTONITE AND FOLLOWING REGENERATION BY BIOLEACHING

<p>The natural bentonite and bentonite/iron oxide composite were used as sorbents of Cu(II). Their sorption properties were examined under the different conditions such as pH of the solution, initial metal ion concentration. The bentonite removed 71 % Cu(II) while composite 90 %. Their maximum adsorption capacities were 34.1 and 44.4 mg Cu(II) g -1, respectively. The chemical regeneration of composite sorbent by organic acids (oxalic, citric) led to partial Cu(II) dissolution. The hydrochloric acid caused its structural destruction. For the bacterial regeneration, the sorbents were inoculated with heterotrophic indigenous bacteria. After 10 days the bacteria released approximately 80 % of loaded Cu(II), leaving the sorbents stable. Longer treatment and higher concentration of metal cations caused the reverse sorption of Cu(II) by bacteria. The regenerated sorbent was successfully repeatedly used for the Cu(II) adsorption.</p>

Sorption of Ag+ and Cu2+ by Vermiculite in a Fixed-Bed Column: Design, Process Optimization and Dynamics Investigations

Vermiculite has been used for the removal of Cu 2 + and Ag + from aqueous solutions in a fixed-bed column system. The effects of initial silver and copper ion concentrations, flow rate, and bed height of the adsorbent in a fixed-bed column system were investigated. Statistical analysis confirmed that breakthrough curves depended on all three factors. The highest inlet metal cation concentration (5000 mg/dm3), the lowest bed height (3 cm) and the lowest flow rate (2 and 3 cm3/min for Ag + and Cu 2 + , respectively) were optimal for the adsorption process. The maximum total percentage of metal ions removed was 60.4% and 68.7% for Ag+ and Cu2+, respectively. Adsorption data were fitted with four fixed-bed adsorption models, namely Clark, Bohart–Adams, Yoon–Nelson and Thomas models, to predict breakthrough curves and to determine the characteristic column parameters. The adsorbent was characterized by SEM, FTIR, EDS and BET techniques. The results showed that vermiculite could be applied as a cost-effective sorbent for the removal of Cu 2 + and Ag + from wastewater in a continuous process.

Determination of Human Safe Metal Cation Concentrations in Surface Water Used to Prepare Drinking Water

The article proposes a method of determination of the required quality for surface water used to prepare drinking water with the acceptable level of a risk to public health when consuming the drinking water. Data tuples were generated as a result of a special monitoring composition study of surface water within the water intake zone and drinking water sampled in houses and apartments. These data tuples were used as a basis for constructing regression models connecting metal cation concentrations in water of the water intake and piped drinking water. Threshold concentrations of metals in surface water within the water intake of Kazan were calculated by solving inverse problems such as Cauchy ones based upon given acceptable values (a level of carcinogenic risk and a background cation concentration of metals without carcinogenic potential).

TiO2 Assisted Photodegradation for Low Substrate Concentrations and Transition Metal Electron Scavengers

Some contaminants of emerging concern (CECs) are known to survive conventional wastewater treatment, which introduces them back to the environment, allowing them to potentially cycle into drinking water. This is especially concerning because of the inherent ability of some CECs to induce physiological effects in humans at very low doses. Advanced oxidation processes (AOPs) such as TiO2-based photocatalysis are of great interest for addressing CECs in aqueous environments. Natural water resources often contain dissolved metal cation concentrations in excess of targeted CEC concentrations. These cations may significantly adversely impact the degradation of CECs by scavenging TiO2 surface generated electrons. Consequently, simple pseudo-first-order or Langmuir-Hinshelwood kinetics are not sufficient for reactor design and process analysis in some scenarios. Rhodamine Basic Violet 10 (Rhodamine B) dye and dissolved [Cu2+] cations were studied as reaction surrogates to demonstrate that TiO2-catalyzed degradation for very dilute solutions is almost entirely due to the homogeneous reaction with hydroxyl radicals, and that in this scenario, the hole trapping pathway has a negligible impact. Chemical reaction kinetic studies were then carried out to develop a robust model for RB-[Cu2+] reactions that is exact in the electron pathways for hydroxyl radical production and electron scavenging.

Selective metal cation concentration during the solidification of stainless steel EAF dust and slag mixtures from high temperatures for increased Cr recovery

The selective concentration of valuable metal cations in FetO-Cr2O3-NiO-MnO-containing stainless steel dust has been studied. The hazardous metal cations Fe, Cr, Ni and Mn could be locally concentrated during the solidification of a molten stainless steel slag and dust mixture from high temperatures by controlling the primary crystalline spinel phase. The nucleation and growth of the primary spinel phase could be controlled by varying the slag to dust mixing ratio and the cooling temperature. Significant redistribution between the primary spinel and amorphous phases could be observed, where the contents of Cr and Mn in the crystalline phase could be increased up to 40% and 10%, respectively, from their initial contents of 5% and 4% in the melt. Using the specified controlled cooling conditions, a primary spinel phase concentrated with Fe-Cr-Ni-Mn could be formed, which could be clearly distinguished and eventually separated from the amorphous matrix. The mixed stainless steel slag and dust samples were quenched at various cooling temperatures and with varying amounts of dust to identify and optimize the crystalline phases formed using SEM-EDS (scanning electron microscopy-energy dispersive spectroscopy) and XRD (X-ray diffraction) analyses.

SYNTHESIS, COORDINATION AND ACID-BASE PROPERTIES OF MESO-DINITROSUBSTITUTED DERIVATIVES OF 5,15-DIPHENYL-β-OCTAALKYLPORPHINE

Presented work shows results of synthesis and spectrophotometric researches on properties of meso-dinitrosubstituted derivatives of 5,15-diphenyl-β-octaalkylporphyrin nitroderivatives in comparison with 2,8,12,18,3,7,13,17-octaethylporphyrin and 2,3,7,8,12,13,17,18-octaethyl-5,15-dinitroporphyrin. The method of spectrophotometric titration with perchloric acid (for determining the basicity constant) and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) was used in order to study the acid-base properties of porphyrins, namely to determine the acidity constant. The spectral characteristics of the ionized forms of 5,15-dinitro-10,20-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporfin-F (I) and 5,15-dinitro-10,20-bis(4-nitrophenyl)-2,8,12,18-tetramethyl-3,7,13,17-tetraethylporphyrin (II) and the corresponding total constants of the acidic (pKa (I) = 6.00 and pKa (II) = 5.27) and the basic (pKb (I) = 19.78 and pKb (II) = 19.83) ionization were provided. The reaction of complexation of porphyrins with zinc acetate was studied by spectrophotometric method in pure acetonitrile and in mixed AN + DBU solvent. The influence of the degree of deformation of the tetrapyrrole macroring, the electronic effects of substituents and the acidity of the medium on the coordination and acid-base properties of porphyrins was analyzed. It was shown that the reactions of formation of metalloporphyrins with anionic porphyrin forms proceed with much higher rates compared to molecular ones, that is accompanied with a decrease in the energy parameters of the reaction. This is evidently due to the absence of energy costs for the deformation and cleaving N-H bonds of the reaction center, as well as the stronger polarization of the molecule, and as a consequence, the higher degree of solvation of anionic forms of porphyrins in the transition state. Thus, the determination of the conditions for the existence of dianionic forms of porphyrins gives grounds for the development of new sensor systems for the recognition and determination of the concentration of metal cations in liquid media due to a sharp increase in the rate of formation of metalloporphyrins in the presence of an organic base.Forcitation:Pukhovskaya S.G., Ivanova Yu.B., Erzunov D.A., Semeykin A.S., Syrbu S.A. Synthesis, coordination and acid-base properties of meso-dinitrosubstituted derivatives of 5,15-diphenyl-β-octaalkylporphine. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 17-28

ANTITOXIC AND NEPHROPROTECTIVE ACTION OF "POLYPHITOL-1" PHYTO-COMPOSITION IN CASE OF CADMIUM INTOXICATION IN YOUNG NOT SEXUALLY MATURE RATS

Abstract. Under conditions of increasing pollution of the environment medical and biological studies related to prophylaxis and treatment of adverse influence of ecotoxicants in respect to age are of great importance. Young organism is especially sensitive to the influence of toxic agents because of the insufficient development of the main regulatory systems, imperfection of mechanisms of protection, low adaptability, and morphological and functional characteristics of the organism.Objective - to study protective influence of the phytopreparation Polyphitol-1 on the total toxicity and functional status of kidneys under conditions of experimental cadmium toxicosis in young not sexually mature animals.Material and methods. The study was conducted with young (5-6 weeks) juvenile male rats in the period of their growth and sexual maturation. Subchronic intoxication was induced by daily administration of cadmium chloride into the stomach for 30 days (0.03 mg/kg). Polyphitol-1 (PPh-1) was administered into the stomach at a dose of 2.5 ml/kg 2 hours before administering the dose of the metal. On the 30th day the content of cadmium ions in the organism was examined, together with indexes of excretory, ionic, and acidic regulating function of the kidneys. The intact animals of the same age, lived under the similar vivarium conditions, were used as the control.Results. It was found that the body mass of the intoxicated animals increased only 15.9% for 30 days in comparison with the initial level; this number is 3.7 times less than for the control animals. Owing to PPh-1 administration the mass of the animals increased 39.4%; this is 2.5 times higher than for the intoxicated animals. Under conditions of cadmium intoxication the most sensitive target organs, where the accumulation of cadmium turned out to be the highest, are the kidneys and liver. The content of metal cations in them grew in 17.0 and 8.6 times, respectively. Under the influence of PPh-1 the accumulation of metal in the organism of animals lowered, specifically in the liver – by a factor of 1.8, in the kidneys – by a factor of 1.7. Against a background of cadmium nephrotoxicity medical and preventive administration of PPh-1 increased diuresis by a factor of 1.3, significantly lowered proteinuria; glomerular filtration, depressed under conditions of metal toxicosis, increased by a factor of 1.9, which halved the level of creatinine in the blood plasma down to the level of the control animals. The transport of sodium ions in nephron intensified, its proximal reabsorbtion increased by a factor of 2.3. The filtration fraction of sodium ions increased by a factor of 2.2, and their excretive fraction and clearance decreased by a factor of 2,6-3,0. Also, the compromised tubular-glomerular feedback was restored.Conclusions. Medical and preventive administration of PPh-1 phytocomposition lowers the toxic influence of cadmium intoxication on the organism of young not sexually mature animals (suppresses the inhibitory influence of cadmium chloride on the physiological increase of the body mass, decreases the accumulation of cadmium ions in the organism). Administration of PPh-1 restores the rate of glomerular filtration, eliminates retention azotemia, activates the transport of sodium in the nephron, which promotes its reabsorbtion and decreases its loss by the organism. Owing to its nephroprotective action, PPh-1 normalizes the disordered excretory, ionic and acidic regulating functions of the kidneys, restores the mechanisms of glomerular-tubular and tubular-tubular equilibrium and tubular-glomerular feedback.

Capture of Pb2+ and Cu2+ Metal Cations by Neisseria meningitidis-type Capsular Polysaccharides.

Heavy metal pollution of water is a significant environmental and public health concern. Current biological strategies for heavy metal removal from water are performed using microbial biopolymers, including polysaccharides, that are already fully formed. This creates limitations in adapting polysaccharides to increase binding affinity for specific metals. We propose that altering the specificity of polysaccharide-producing enzymes could be beneficial to improving metal capture by modified polysaccharides. We assess binding of Cu2+ and Pb2+ metal cations to Neisseria meningitidis-type polysaccharides. All concentrations of metal cations tested were able to completely bind to colominic acid. This polymer is equivalent to the capsular polysaccharide of N. meningitidis serogroup B comprised of a homopolymer of negatively charged sialic acid. There was slightly less binding observed with N. meningitidis serogroup W, which contains repeating units of the neutral sugar galactose and sialic acid. Our work represents the first assessment of the metal-binding properties of these capsular polysaccharides. Future work will seek to optimize metal-binding with Neisseria meningitidis serogroup W polysaccharide.

Understanding the Effects of pH and Alkali Metal Cations on H/OH Adsorption and the Hydrogen Oxidation/Evolution Reaction on Transition Metal Electrodes

The structure and composition of the complex electrode/electrolyte interface have a direct effect on the rate and mechanisms of electrocatalytic reactions. Recent experimental evidence has shown that the rate of the hydrogen oxidation and evolution reactions (HOR/HER) are strongly dependent on electrolyte pH; the rate on the most active catalyst, platinum, is two orders of magnitude slower in an alkaline electrolyte than in an acid electrolyte [1]. This pH dependence has been correlated with an anomalous pH dependence of the sharp, low potential peaks in current measured by cyclic voltammetry on polycrystalline and nanoparticle platinum electrodes, believed to be due to hydrogen adsorption on 110 and 100 step sites [2]. In our prior work, we used density functional theory (DFT) to show that these sharp peaks measured by cyclic voltammetry correspond to competitive hydrogen and hydroxide adsorption onto 110 and 100 step sites and not solely hydrogen adsorption. We further showed that the apparent pH dependence of the location of these step-associated peaks is actually due to the co-adsorption of alkali metal cations, which weaken hydroxide adsorption along the step, shifting these peaks to more positive potentials [3]. We have recently extended this work using both single crystal experiments and DFT to find that the location of the sharp, step-associated peak is independent of pH in the absence of alkali metal cations and is dependent on alkali metal cation concentration and identity, supporting that this effect is mediated by the presence of alkali metal cations along the step [4]. We also find the rate of the hydrogen oxidation reaction on a polycrystalline platinum electrode to be dependent on the identity of the alkali metal cation present in an alkaline electrolyte, and using DFT find that the rate of the HOR is correlated with the alkali cation dependent hydroxide binding strength. Given that we find only a small interaction between the adsorbed cations and adsorbed hydrogen, we support that adsorbed hydroxide may play a role in the HOR mechanism, as has been previously proposed [5]. We show a volcano-type relationship between the experimentally measured hydrogen oxidation rate with the DFT calculated hydroxide adsorption potential across a variety of surfaces. A proposed mechanism will be discussed. [1] W. Sheng, H. A. Gasteiger, Y. Shao-Horn, “Hydrogen oxidation and evolution reaction kinetics on platinum: acid vs alkaline electrolytes,” JECS, vol. 157, pp. B1529-B1536, 2010.[2] W. Sheng, Z. Zhuang, M. Gao, J. Zheng, J. G. Chen, Y. Yan, “Correlating hydrogen oxidation and evolution activity on platinum at different pH with measured hydrogen binding energy,” Nat. Commun., 6:5848, 2015. [3] I. T. McCrum, M. J. Janik, “First principles simulations of cyclic voltammograms on stepped Pt(553) and Pt(533) electrode surfaces,” ChemElectroChem, vol. 3, pp. 1609-1617, 2016.[4] X. Chen, I. T. McCrum, K. A. Schwarz, M. J. Janik, M. T.M. Koper, “Co-adsorption of cations as the cause of the apparent pH dependence of hydrogen adsorption on a stepped platinum single-crystal electrode,” Angew. Chem. Int. Ed. doi:10.1002/anie.201709455[5] D. Strmcnik, M. Uchimura, C. Wang, R. Subbaraman, N. Danilovic, D. van der Vliet, A. P. Paulikas, V. R. Stamenkovic, N. M. Markovic, “Improving the hydrogen oxidation reaction rate by promotion of hydroxyl adsorption,” Nature Chemistry, vol. 5, pp. 300-306.

Textured WO3 and WO3:Mo films deposited from chemical solution on stainless steel

Tungsten trioxide (WO3) and molybdenum-doped tungsten trioxide (WO3:Mo) films were deposited on stainless steel surface by a chemical aqueous solution approach using dip-coating technique. The deposited 5, 10 and 15-layer films were homogeneous and continuous. The surface morphology and crystallinity of the produced films were dependent on the metal cation species and concentration of PVA in the solution. FE-SEM analysis revealed the formation of textured WO3 film surfaces having spike-like nanostructures. The values of the static water contact angle measured on the film surface showed that deposited WO3 films can exhibit both hydrophilic and hydrophobic nature, while WO3:Mo films showed hydrophilic behavior. Tribological properties of the deposited films were evaluated in deionized water. All three coatings retained a lubricating layer much better than original steel, demonstrating major reduction in friction and wear. Particularly effective were PVA-free WO3 films, whose friction coefficient stayed under 0.2 for over 2000 cycles. Excellent tribological, hydrophobic and hydrophilic properties along with simple deposition methods suggest very promising potential of WO3 and WO3:Mo coatings in industrial applications.

Induction of Colony Formation of <i>Microcystis aeruginosa</i> by Controlling Extracellular Polysaccharides and Metal Cation Concentrations

Induction of Colony Formation of <i>Microcystis aeruginosa</i> by Controlling Extracellular Polysaccharides and Metal Cation Concentrations

Relationship between the zeta potential and the chemical agglomeration efficiency of fine particles in flue gas during coal combustion

Fly ash fine particles emitted from flue gas during coal combustion are the primary atmospheric pollutants in China. The purpose of this study was to investigate the characteristics of the zeta potential of fine particle suspensions. The relationship between the zeta potential and the fine particle removal efficiency was also discussed. Batch experiments were conducted to evaluate the zeta potential of fine particle aqueous solutions under various pH, ion concentration, surfactant, polymer, and chemical agglomeration solution conditions. A chemical agglomeration system was designed to simulate the removal process of the fine particles. The test results indicated that the zeta potential absolute value of the solution decreased initially and then increased as the pH increased. As the pH increased from 4 to 12, the zeta potential decreased from Zp = 9.4 mV to Zp = −45.4 mV. The isoelectric point (IEP) was 4.3. Also at the IEP, the highest fine particle removal efficiency of 25.9% was achieved. The zeta potential increased as the metal cation concentration of the solutions increased. The trivalent cation Al3+ exhibited the best performance, which increased Zp from −32.1 mV to −11.2 mV and produced the highest fine particle removal efficiency of 9.2%. Polymers significantly impacted the zeta potential. As the concentration of kappa-carrageenan (CAR) increased from 0.01% to 5%, the zeta potential increased from −30.1 mV to 12.6 mV. The highest fine particle removal efficiency of 41.8% was acquired at a concentration of 0.5%, which had the lowest zeta potential absolute value of 3.5 mV. It can be inferred that the increase in the zeta potential induced the growth of the energy barrier, which prevented particle agglomeration. The suspension with a lower zeta potential exhibited a better fine particle removal efficiency.

Neural Network Self-Learning Model for Complex Assessment of Drinking Water Safety for Consumers

We need to take into complex assessment a set of influencing factors of drinking water safety. This raises the task of developing an integrated methodology assessing the safety of drinking water that reaches the consumers. For the integrated assessment of the safety of drinking water, the method of clustering was chosen, namely, the neural network method of Kohonen self-organizing maps. Zones were separated by the method of cluster neural network analysis. The zones are characterized by different content of metal cations in drinking water, levels of carcinogenic and non-carcinogenic risk to the health of the child population, and the probability of the receipt of metal cations with potable water to consumers.

Evidence for Considerable Metal Cation Concentrations from Lithium Intercalation Compounds in the Nano–Bio Interface Gap

An experimental investigation of how electrostatics and ion dissolution impact the interaction between nanosheets of lithium intercalation compounds and supported lipid bilayers has revealed evidence for considerable metal cation concentrations in the nanosheets–bilayer (the “nano–bio interface”) gap. Specifically, elevated concentrations of aqueous metal ions in the 1 mg/L concentration regime produce vibrational sum frequency generation signal intensity changes that are commensurate with the induction of compositional membrane asymmetry. This outcome is consistent with the notion that the induction of bilayer asymmetry by LiCoO2 nanosheets occurs through a noncontact mechanism that primarily involves the interaction of negatively charged lipids with dissolved ions concentrated within the electrical double layers present in the nano–bio interface gap. Our findings provide a possible avenue for redesign strategies that mitigate noncontact interactions between nanomaterials and biological interfaces, enabl...

Involvement of the exomer complex in the polarized transport of Ena1 required for Saccharomyces cerevisiae survival against toxic cations.

Exomer is an adaptor complex required for the direct transport of a selected number of cargoes from the trans-Golgi network (TGN) to the plasma membrane in Saccharomyces cerevisiae However, exomer mutants are highly sensitive to increased concentrations of alkali metal cations, a situation that remains unexplained by the lack of transport of any known cargoes. Here we identify several HAL genes that act as multicopy suppressors of this sensitivity and are connected to the reduced function of the sodium ATPase Ena1. Furthermore, we find that Ena1 is dependent on exomer function. Even though Ena1 can reach the plasma membrane independently of exomer, polarized delivery of Ena1 to the bud requires functional exomer. Moreover, exomer is required for full induction of Ena1 expression after cationic stress by facilitating the plasma membrane recruitment of the molecular machinery involved in Rim101 processing and activation of the RIM101 pathway in response to stress. Both the defective localization and the reduced levels of Ena1 contribute to the sensitivity of exomer mutants to alkali metal cations. Our work thus expands the spectrum of exomer-dependent proteins and provides a link to a more general role of exomer in TGN organization.

Crevice Corrosion of Stainless Steels 904L, 2205, and 2507 in High-Temperature Sulfuric Acid Solution Containing Chlorides: Influence of Metal Cations

Crevice corrosion influences the integrity of materials in many industrial sectors, such as hydrometallurgy. The conditions in hydrometallurgical processes are severe, with high concentrations of sulfuric acid leachant as well as high-chloride impurity, oxygen, and metal cation contents. In this study, crevice corrosion behavior of highly-alloyed austenitic and duplex stainless steels is investigated in aerated high-temperature sulfuric acid solution with 1 g/L chlorides in the presence of three types of metal cations: Fe3+, Cu2+, and Fe2+. The experimental work contains the determination of the oxidizing capacity of the solutions, immersion crevice corrosion tests followed by characterization of the corrosion attack, and potentiodynamic polarization measurements. The results show that the alloy with the highest PREN value, grade 2507, was not susceptible to crevice corrosion under the test conditions. In the case of grades 904L and 2205 of relatively equal PREN values, the extent and nature of crevice corrosion attack was different and dependent on the ratio of activities of chlorides to sulfates and the type of metal cations. The results are presented and discussed in the light of IR drop mechanism.

Study of Complexation Equilibria Between the Iron(III) Ion and 2-Hydroxybenzamide in Aqueous Solution

The complexation of the Fe3+ ion with 2-hydroxybenzamide (salicylamide, HL) has been studied, at 25.0 °C, by potentiometric measurements with a glass electrode in 1 mol·dm−3 NaClO4 medium. The concentration of salicylamide (C L) has been varied between (1 × 10−3 and 10 × 10−3) mol·dm−3, while the concentration of metal cation (C M) ranged within (0.5 × 10−3 and 10 × 10−3) mol·dm−3. The ligand to metal concentration ratio has been varied between 1 and 10 and the hydrogen ion concentration was decreased stepwise until the incipient precipitation of a basic salt of the metal, which occurred at different values depending on the specific ligand to metal ratio. The experimental data were consistent with the formation of the complexes FeL2+, Fe(HL)L2+ and $$ {\text{FeL}}_{2}^{ + } $$ . Equilibrium formation constants have been given for the investigated ionic medium as well as for the infinite dilution reference state, evaluated according to the Specific Interaction Theory. The predominant species in neutral solution are $$ {\text{FeL}}_{2}^{ + } $$ and $$ {\text{Fe}}\left( {\text{OH}} \right)_{2}^{ + } $$ .