Página 1 dos resultados de 1513 itens digitais encontrados em 0.015 segundos

‣ Interaction between lactose and cadmium chloride in aqueous solutions as seen by diffusion coefficients measurements

Verissimo, Luis M. P.; Gomes, Joselaine C. S.; Romero, Carmen; Esteso, Miguel A.; Sobral, Abilio J. F. N.; Ribeiro, Ana C. F.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.41615%
Diffusion coefficients of an aqueous system containing cadmium chloride 0.100 mol · dm−3 and lactose at different concentrations at 25 °C have been measured, using a conductimetric cell and an automatic apparatus to follow diffusion. The cell relies on an open-ended capillary method and a conductimetric technique is used to follow the diffusion process by measuring the resistance of a solution inside the capillaries, at recorded times. From these results and by ab initio calculations, it was possible to obtain a better understanding of the effect of lactose on transport of cadmium chloride in aqueous solutions.

‣ The electrochemical behaviour of Ti-13Nb-13Zr alloy in various solutions

ASSIS, S. L.; WOLYNEC, S.; COSTA, I.
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.89777%
The electrochemical behaviour of a near-beta Ti-13Nb-13Zr alloy for the application as implants was investigated in various solutions. The electrolytes used were 0.9 wt% NaCl solution, Hanks` solution and a culture medium known as minimum essential medium (MEM) composed of salts, vitamins and amino acids, all at 37 degrees C. The electrochemical behaviour was investigated by the following electrochemical techniques: open circuit potential measurements as a function of time, electrochemical impedance spectroscopy (EIS) and determination of polarisation curves. The obtained results showed that the Ti alloy was passive in all electrolytes. The EIS results were analysed using an equivalent electrical circuit representing a duplex structure oxide layer, composed of an inner barrier layer, mainly responsible for the alloy corrosion resistance, and an outer and porous layer that has been associated to osteointegration ability. The properties of both layers were dependent on the electrolyte used. The results suggested that the thickest porous layer is formed in the MEM solution whereas the impedance of the barrier layer formed in this solution was the lowest among the electrolytes used. The polarisation curves showed a current increase at potentials around 1300 mV versus saturated calomel electrode (SCE)...

‣ Voltammetric study of Al-Zn-Mg alloys in chloride solutions

Garrido, J. A.; Cabot, P. L.; Rodriguez, R. M.; Perez, E.; Moreira, A. H.; Sumodjo, PTA; Benedetti, A. V.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica Formato: 1241-1244
Português
Relevância na Pesquisa
47.02357%

‣ Electrochemical behaviour of heat-treated Al-Zn-Mg alloys in chloride solutions containing sulphate

Moreira, A. H.; Benedetti, A. V.; Sumodjo, PTA; Garrido, J. A.; Cabot, P. L.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 2823-2831
Português
Relevância na Pesquisa
57.536904%
The electrochemical corrosion and passivation of Al-5Zn-1.7Mg-0.23Cu-0.053Nb alloys, submitted to different heat treatments (cold-rolled, annealed, quenched and aged, and quenched in two steps and aged), in sulphate-containing chloride solutions, has been studied by means of cyclic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS). The cyclic polarization curves showed that sulphate addition to the chloride solution produced a poor reproducible shift of the breakdown potential to more positive potentials. The repassivation potentials, much more reproducible, and practically separating the passive from the pitting potential region, were slightly displaced in the negative direction with that addition. When the alloys were potentiodynamically polarized in the passive potential region, sulphate was incorporated in the oxide film, thus precluding chloride ingress. In addition, Zn depletion was favoured, whereas Mg losses were avoided. Different equivalent circuits corresponding to different alloys and potentials in the passive and pitting regions were employed to account for the electrochemical processes taking place in each condition. This work shows that sulphate makes these alloys more sensitive to corrosion...

‣ New extractants for separation of platinium-group metals from chloride solutions and their application to recycling processes

Paiva, A. P.; Carvalho, G. I.; Schneider, A. L.; Costa, M. Clara; Costa, A. M.; Assunção, A. F.; Nogueira, C. A.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em 10/09/2012 Português
Relevância na Pesquisa
57.387046%
In this paper some results on the application of four N,N’-tetrasubstituted malonamide derivatives for the extraction and separation of platinum-group metals (PGMs) are presented. The above mentioned extractants were specifically synthesized in order to evaluate their efficiency for the extraction of a specific metal, or group of metals, from aqueous chloride matrices. Different behaviours were obtained towards platinum(IV) and/or palladium(II) extraction, all the N,N’-tetrasubstituted malonamide derivatives allowing the mutual separation of the two metal ions, depending on the HCl concentration. Generally, extraction experiments were carried out involving initial aqueous phases containing 100 mg/L of each metal isolate, in varying 1M to 8M HCl concentration ranges, and 0.05M extractant in 1,2- dichloroethane solutions. From the preliminary results obtained, one can conclude that HCl concentrations and the structure of the malonamide derivative play a crucial role on the efficiency shown for Pt(IV) and/or Pd(II) extraction. The efficiency of the stripping stage of the loaded organic phases is variable, depending on the N,N’-tetrasubstituted malonamide derivative, as well as on the metal ion involved; for Pt(IV), distilled water and 1M HCl were generally successful...

‣ Analysis of the initial stages of electrocrystallization of Fe, Co and Fe-Co alloys in chloride solutions

Bento,Fábio R.; Mascaro,Lucia H.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2002 Português
Relevância na Pesquisa
47.218857%
The electrodeposition of Fe, Co and Fe-Co alloys onto Pt has been investigated from chloride solutions at pH 2.0. The Fe-Co alloys were deposited from solutions with molar ratio of 1:10, 1:1 and 10:1. Electrocrystallization of metals was studied by potentiostatic steps. The Scharifker and Hills model was used to analyze current transients. A progressive nucleation mechanism was found to fit the experimental results for both Co and Fe-Co alloys deposited from 1:10 solution. In the case of pure Fe and Fe-Co alloy, deposited from 1:1 and 10:1 solutions, the nucleation process occurred by the instantaneous mechanism. The nuclei number densities and rate of nucleation were calculated and their values were 2.6 to 19.1 x 10³ cm-2 for Fe and 0.10 to 15.8 x 10(6) cm-2 s-1 for Co deposition.

‣ 3-phenyl-4-acyl-5-isoxazolones as reagents for liquid-liquid extraction of tetravalent zirconium and hafnium from acidic chloride solutions

Reddy,B. Ramachandra; Kumar,J. Rajesh; Reddy,A. Varada
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2006 Português
Relevância na Pesquisa
67.31265%
Liquid liquid extraction of tetravalent zirconium and hafnium from acidic chloride solutions has been investigated using 3-phenyl-4-acyl-5-isoxazolones in xylene such as 3-phenyl-4-benzoyl-5-isoxazolones (HPBI), 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone (HFBPI) and 3-phenyl-4-(4-toluoyl)-5-isoxazolone (HTPI). The extraction of zirconium(IV) / hafnium(IV) shows a ion exchange mechanism: MO2+ (aq) + 2 HA (org) « MOA2 (org) + 2 H+(aq), where M = Zr(IV) / Hf(IV) and HA = HPBI or HFBPI or HTPI. The variation of the D ([MOA2] (org) / [MO2+](aq); ratio of the possible extraction equilibrium species) values with an increase of the acid / extractant concentration showed a linear plot with a slope of 2. The effect of the nature of the diluents like carbon tetrachloride, cyclohexane, n-hexane, benzene, nitrobenzene, xylene, toluene and chloroform on the extraction of zirconium(IV) / hafnium(IV) has been studied. The extraction behavior of zirconium(IV) / hafnium(IV) was also compared with that of other metal ions like titanium(IV), aluminium(III) and iron(III), which can be generally associated with the metal ions studied.

‣ Diffusion of lysozyme chloride in water and aqueous potassium chloride solutions.

Cadman, A D; Fleming, R; Guy, R H
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1982 Português
Relevância na Pesquisa
47.365376%
The diffusion of lysozyme chloride in aqueous solution has been studied at 25 degrees C using the Goüy interferometric technique. The concentration dependence of the diffusion coefficient in water has been measured over the concentration range 1.1599-9.1556 gcm-3 and the results suggest a value of D 25, w at infinite dilution of 5.838 x 10(-6) cm2s-1. The variation in diffusion coefficient with ionic strength has also been considered by following the diffusion of 0.45% lysozyme chloride in a series of potassium chloride solutions. The value of D in 0.15 M KCl has been found to be approximately one quarter of that in water alone an the diffusion coefficient has been shown to increase markedly as the KCl concentration is reduced below 0.05 M. Interpretation of these observations involves consideration of solution electrostatic effects.

‣ STUDIES IN EDEMA : II. THE INFLUENCE OF THE ADDITION OF ADRENALIN TO SOLUTIONS OF SODIUM CHLORIDE AND OF SODIUM CHLORIDE AND CALCIUM CHLORIDE SOLUTIONS AND OF A MORE RAPID RATE OF INFLOW UPON THE PRODUCTION OF URINE, ASCITES AND INTESTINAL FLUID.

Fleisher, Moyer S.; Loeb, Leo
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/05/1909 Português
Relevância na Pesquisa
47.954478%
1. In non-nephrectomized animals the addition of adrenalin to sodium chloride solutions or to mixtures of sodium chloride and calcium chloride solutions increases the amount of urine and of ascites, and diminishes the intestinal fluid (this diminution takes place only with mixtures of solutions of sodium chloride and calcium chloride, the quantity of intestinal fluid remaining approximately unchanged in the sodium chloride series). 2. In nephrectomized animals the addition of adrenalin to sodium chloride solutions or to mixtures of sodium chloride and calcium chloride solutions again increases the ascites and diminishes the amount of intestinal fluid in both sodium chloride and sodium chloride plus calcium chloride series. 3. We find, therefore, a summation of the action of calcium chloride and adrenalin in regard to their influence upon the formation of ascites, an antagonistic action in regard to the elimination of urine; here the influence of calcium chloride in diminishing the urine is more potent than is the action of adrenalin in increasing the amount of urine. The adrenalin decreases the elimination of fluid into the intestines and in this case we note a summation of the actions of calcium chloride and of adrenalin. 4. We see...

‣ Effects of low-chloride solutions on action potentials of sheep cadiac purkinje fibers

Kenyon, JL; Gibbons, WR
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 01/11/1977 Português
Relevância na Pesquisa
47.790435%
The rapid repolarization during phase 1 of the action potential of sheep cardiac purkinje fibers has been attributed to a time- and voltage-dependent chloride current. In part, this conclusion was based on experiments that showed a substantial slowing of phase 1 when larger, presumably impermeant, anions were substituted for chloride in tyrode’s solution. We have re- examined the electrical effects of low-chloride solutions. We recorded action potentials of sheep cardiac purkinje fibers in normal tyrode’s solution and in low-chloride solutions made by substituting sodium propionate, acetylglycinate, methylsulfate, or methanesulfonate for the NaCl of Tyrode’s solution. Total calcium was adjusted to keep calcium ion activity of test solutions equal to that of control solutions. Propionate gave qualitatively variable results in preliminary experiments; it was not tested further. Low-chloride solutions made with the other anions gave much more consistent results: phase 1 and the notch that often occurs between phases 1 and 2 were usually unaffected, and the action potential duration usually increased. The only apparent change in the resting potential was a transient 3-6 mV depolarization when low-chloride solution was first admitted to the chamber...

‣ Stability of Melphalan in 0.9 % Sodium Chloride Solutions Prepared in Polyvinyl Chloride Bags for Intravenous Injection

Desmaris, Romain-Pacôme; Mercier, Lionel; Paci, Angelo
Fonte: Springer International Publishing Publicador: Springer International Publishing
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.490547%
Melphalan is an alkylating agent frequently used in an intravenous formulation to treat hematologic malignancies and solid tumors in both adults and children. According to the manufacturer, melphalan is stable in sterile 0.9 % sodium chloride for 90 min at room temperature (RT). Several authors have studied the stability of different concentrations of melphalan; however, most were not adapted to the current manufacturing process applied in pharmaceutical centralized units. This study was conducted to determine the stability of melphalan in 0.9 % sodium chloride solutions at concentrations used for intravenous injection in practice. Melphalan is commonly prepared in diluted solutions ranging from 2 to 4 mg/ml for the treatment of adult patients and at lower concentrations (down to 0.5 mg/ml) for pediatric use. Accordingly, these were the three concentrations chosen for this study. Melphalan concentrations were measured with high-performance thin-layer chromatography (HPTLC). At RT, admixtures prepared at 4 mg/ml were stable for up to 8 h without protection from light; however, at lower concentrations, such as 0.5 and 2 mg/ml, stability did not exceed 2 h. When refrigerated, melphalan was stable for 24 h at 2 mg/ml; however...

‣ Copper(I) speciation in mixed thiosulfate-chloride and ammonia-chloride solutions: XAS and UV-Visible spectroscopic studies

Etschmann, B.; Black, J.; Grundler, P.; Borg, S.; Brewe, D.; Mcphail, D.; Spiccia, L.; Brugger, J.
Fonte: Royal Society of Chemistry Publicador: Royal Society of Chemistry
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
47.73638%
Thiosulfate and ammonia mixtures may be more environmentally benign alternatives to cyanide for leaching Au from ores. In this method, the Cu(I)/Cu(II) couple acts as a redox mediator aiding in the oxidative dissolution of metallic Au. Information about the speciation of Cu(I) and Cu(II) in these lixiviant solutions is paramount to the optimization of gold ore processing conditions. With this in mind, we have carried out XANES, EXAFS and UV-Vis spectroscopic studies of the speciation of Cu(I) in mixed thiosulfate-chloride and ammonia-chloride solutions. In thiosulfate-chloride solutions, the EXAFS studies indicate that the geometry of the predominant Cu(I) complex is distorted trigonal (triangular planar), with an average of 2 sulfur atoms + 1 oxygen atom occupying the coordination sphere. This indicates that the stability of the [Cu(S2O3)3]5− complex is lower than previously proposed. Formation constants for Cu(I) thiosulfate complexes have been derived on the basis of systematic UV-Vis measurements of solutions with varying [S2O3]/[Cl] ratios. Only one mixed chloride-thiosulfate complex, [Cu(H2O)(S2O3)Cl]2−, was found to predominate over the range of conditions investigated. For Cu(I) in ammonia-chloride solutions, our results confirm the broad stability of [Cu(NH3)2]+ and we have also identified a stable mixed amminechlorocopper(I) complex...

‣ Gold chloride technique to study articular innervation. A protocol validated through computer-assisted colorimetry

Gómez-Barrena, E.; Martinez-Moreno, E.; Ballesteros Massó, R.; Martinez Perez, D.; Munuera Martinez, L.
Fonte: Murcia : F. Hernández Publicador: Murcia : F. Hernández
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
47.223506%
We studied variations in gold chloride techniques to elicit neural elements within articular samples, after "in toto" staining. These techniques attempt the differentiation of neural and vascular structures. Major changes in differential staining were observed when the gold chloride concentration was empirically modified. After the rest of the technique was standardized, we selected three gold chloride solutions to perform quantitative color experiments: l%, 0.75%, and 0.5%. Significant sections of the same thickness were acquired with a digital camera to perform computerassisted colorimetry. Color was measured through RGB (red-green-blue) channels in vessels, nerves, and background connective tissue as an internal control. By means of multivariate regression analysis, we compared differences in color measurements after l%, 0.75% and 0.5% gold chloride preparation. Statistically significant coefficients confirmed that red color signals in vessels after the 0.75% and the 0.5% solution were both less intense than after the 1% preparation. Green and blue signals in vessels were also significantly less intense after the 0.5% protocol than after using the 1% solution. Red color signals in nerves between the 1% and the 0.75% preparation protocols were more intense and not significantly different...

‣ Physicothermal properties of aqueous sodium chloride solutions

Carvalho, G. R.; Chenlo, F.; Moreira, R.; Telis-Romero, J.
Fonte: Wiley-Blackwell Publicador: Wiley-Blackwell
Tipo: Artigo de Revista Científica Formato: 234-242
Português
Relevância na Pesquisa
47.490547%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 2012/13487-2; Physicothermal properties of sodium chloride solutions as complementary information to the existent in literature were experimentally measured under different conditions of mass concentration (in the range of 0.040kg NaCl/kg solution to 0.240kg NaCl/kg solution) and temperature (between 4 and 52 degrees C). Density, dynamic viscosity, specific heat capacity and thermal conductivity were measured using a standard volumetric glass pycnometer, rheometer, differential scanning calorimeter and coaxial dual-cylinder apparatus, respectively. Prandtl number was calculated with the measured properties. Statistical analyses were carried out to determine the effect of the salt concentration and temperature on the properties, and, subsequently, different correlations were proposed to estimate the experimental results with acceptable goodness of fit. Linear relationships were observed among tested properties and sodium chloride concentrations, whereas the temperature dependence was specific for each property.Practical ApplicationsExperimental data about binary solutions, such as sodium chloride solutions, are insufficient, and much specific information is still unknown. The knowledge of this information is necessary in the effective designing of food processing equipment such as evaporators...

‣ The recovery of magnesium oxide and hydrogen chloride from magnesium chloride brines and molten salt hydrates

de Bakker, Jan
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
47.185215%
Hydrochloric acid leaching of saprolite nickel ores has been proposed as an effective means of recovering nickel and cobalt. However, the leach produces a concentrated brine of magnesium chloride which must be hydrolyzed to recover the HCl lixiviant. The processing of carnallite similarly produces a concentrated MgCl2 brine; converting this brine into HCl and MgO provides an attractive way of adding value while effectively disposing of this waste product. Direct pyrohydrolysis of magnesium chloride brines by the reaction, MgCl2,a + H2Oa  MgOs + 2HClg is energy-intensive as large volumes of water must be evaporated. The energy cost is high, and the HCl stream produced is limited to approximately 20 wt% HCl. This thesis explores alternative methods of obtaining HCl from aqueous magnesium chloride solutions. Two methods are considered: the hydrolysis, under autogenous pressure, of concentrated MgCl2 molten salt hydrates; and the precipitation of magnesium hydroxychloride compounds such as 2MgO·MgCl2·6H2O and 3MgO·MgCl2·11H2O, which are subsequently decomposed at high temperature. Considerable experimental difficulties were encountered in studying pressure hydrolysis of molten salt hydrates, despite extensive equipment modifications. Ultimately...

‣ Effect of Degassing on the Electrical Conductivity of Pure Water and Potassium Chloride Solutions

Francis, Mathew
Fonte: American Chemical Society Publicador: American Chemical Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.31265%
Recently, a significantly higher value was reported for the conductivity of pure water, in the absence of dissolved gases. These initial observations have been repeated in this study but with an improved experimental system, giving more accurate results t

‣ The effect of chloride as catalyst layer contaminant on the degradation of PEMFCs

Paiva, T. I.; Hashimoto, T.; Plancha, Maria João; Thompson, G. E.; Rangel, C. M.
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Conferência ou Objeto de Conferência
Publicado em //2013 Português
Relevância na Pesquisa
47.365376%
In this work, the effect of chloride as a catalyst contaminant was studied on the performance and durability of a low power open-cathode fuel cell, intended for passive management of water. In an ex-situ study, cyclic voltammetry was used to assess the redox behaviour of platinum in chloride contaminated solutions at room temperature.The cell was operated integrating a range of relative humidity (RH) from ~30 to 80% and temperatures from 5 to 55 ºC. Results indicated that 60% RH is associated to maximum fuel cell performance over the studied temperature range. An examination of the fuel cell components after 100 h of operation revealed that chloride contamination has produced cathode failure associated to catalyst migration favored by operation conditions that allowed platinum particles to break free from their carbon backing and migrate toward the polymer electrolyte. Migration resulted in precipitation with larger mean particle size distribution within the solid electrolyte when compared to the original catalyst layer, rendering a very significant loss of thickness in the cathode material.

‣ Corrosion mechanism of Al-Zn-In alloys in chloride solutions

Muñoz,A. G.; Saidman,S. B.; Bessone,J. B.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2003 Português
Relevância na Pesquisa
46.960967%
The electrochemical behavior of Al-Zn-In alloys was investigated in chloride media by means of potentiodynamic techniques, complemented by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX) and Transmission Electron Microscopy (TEM). The influence of local alkalization produced by previous cathodization was analyzed at potentials more negative than the rest potential. The electrochemical response of alloys is given by the sum of those corresponding to the different present phases. Thus, the electrochemical behavior of each metal and bimetallic alloy (Al-In, In-Al and Zn-In) was analyzed in the same solution conditions at a potential region near the corrosion potential of the ternary alloy. The low solubility of In in Al favors its segregation at grain boundaries, where the formation of Zn-In alloys was detected. The initiation of the attack in the Al-Zn-In alloy is mainly localized in these zones. This is a consequence of the enhanced adsorption and surface accumulation of Cl- promoted by In at potentials more positive than - 1.1 V SCE. Close similarities of the anodic behaviors of the Al-In and ternary alloys lead us to propose a mechanism where the In distribution plays the major role. The In dissolution from homogeneous solid solution phases allows an enrichment of this element at the Al and Zn rich phases by displacement reactions. (Al...

‣ Effect of saline solutions and salt stress on seed germination of some tropical forest tree species

Agboola,D. A.
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/1998 Português
Relevância na Pesquisa
46.948164%
The effect of several saline solutions (as given by six salts) and salt stress (as given by 0.1 - 2m sodium chloride solutions) on the germination of seeds of six selected tropical forest tree species was investigated. Saline solutions (0.2m) of the six salts used had highly significant effects on seed germination in most of the tree species. Sodium sulphate (Na2So4) permitted germination in the seeds of Ceiba pentandra and Tectona grandis presoaked in its 0.2m solution for 36 and 48h respectively. The Zinc sulphate (ZnSO4) solution enhanced the germination of seeds of Terminalia ivorensis and Terminalia superba. Solution of Potassium per Manganate favoured the germination of seeds of T. grandis, T. ivorensis and T. superba. In general, increase in molar concentration of NaCl adversely affected the germination rate of seeds. Sees of the two Terminalia species could withstand NaCl salt stress. Seeds of T. grandis have high ability to withstand salt stress comparatively.

‣ Evaluation of Nicotiana Leaves Extract as Corrosion Inhibitor for Steel in Acidic and Neutral Chloride Solutions

Abd-El-Khalek,D.E.; Abd-El-Nabeyb,; Abdel-Gaberb,A.M.
Fonte: Sociedade Portuguesa de Electroquímica Publicador: Sociedade Portuguesa de Electroquímica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2012 Português
Relevância na Pesquisa
47.19176%
The inhibition of steel corrosion in hydrochloric acid and sodium chloride solutions by Nicotiana leaves extract was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. Polarization curves showed that the extract behaves as a mixed type inhibitor in acidic medium, while it acts as anodic type in neutral medium. Impedance measurements indicated that the size of the semicircles obtained increased with increasing the concentration of the extract and decreasing the chloride ion concentration. Nicotiana leaves extract was found to be more effective in controlling corrosion of steel in acidic solution than in neutral one. The activation parameters of the corrosion reaction of steel in acid media in absence and presence of nicotiana leaves extract were also calculated and discussed.