Influence Of Chloride Concentration Research Articles

Metallic corrosion of steels embedded in calcium aluminate cement mortars

In the present paper, the corrosion levels of reinforcing steels embedded in Calcium Aluminate Cement (CAC) mortars have been studied. Experiments were designed to investigate the influence of the following factors in steel corrosion: cover thickness, type of steel (carbon steel (CS) and stainless steel (SS)), temperature at mixing and curing, influence of chloride concentration, nitrite ion as corrosion inhibitor and carbonation of mortar. The reinforcing steel bars do not become more corroded because of the carbonation of the CAC mortar cover; in some cases, this carbonation seems to have an inhibitor effect in the steel corrosion. The higher the process of carbonation in CAC, the higher the intensity of the X-ray reflections of Friedel's salt and the smaller the values of corrosion rates.

Measurement of dissolved organic carbon by wet chemical oxidation with persulfate: influence of chloride concentration and reagent volume

Abstract The influence of chloride content and reagent volume on the analysis of dissolved organic carbon by wet chemical oxidation with persulfate was evaluated. A strong hyperbolic relationship was found between measured DOC concentration and volume of persulfate added for oxidation in both marine and artificially chlorinated (NaCl) freshwater samples. Freshwater samples showed no such relationship. Precision of measured DOC concentrations averaged 4–7% and did not vary as a function of persulfate volume. Apparently chloride, and possibly other ions, produce significant interference in the oxidation reaction of organic matter by persulfate. Thus, analysis of DOC in seawater, or water with a high chloride content, by persulfate oxidation may yield erroneously low, yet precise, results if asymptotic concentrations of persulfate are not employed. Use of less than asymptotic concentrations of persulfate may account for some of the variability encountered in intercomparison experiments employing persulfate and high temperature catalytic oxidation methods.

Influence of Chloride Concentration on the Active Dissolution and Passivation of Nickel Electrodes in Acid Sulfate Solutions

The influence of Cl− ion concentration on the active dissolution and passivation of polycrystalline nickel rotating disk electrodes in sulfuric acid‐potassium sulfate solutions at pH 2.6 and 25°C was studied. The voltammetric data suggest that the passive layer results from a complex reaction involving the electrodissolution of the base metal, the formation of the anodic layer and its partial chemical dissolution. The influence of Cl− ions under different hydrodynamic conditions is discussed taking into account the competitive adsorption involving Cl− ions and species containing oxygen at the initial stages of the reaction yielding soluble products, and the appearance of as a new phase. Solution stirring favors the electrodissolution reaction by increasing the transport rate of Cl− and H+ ions to the electrode surface, and simultaneously decreasing the thickness of the layer.

Chloride effect on the extraction rate of Cu with 2-hydroxy-5-nonylbenzophenone oxime

The influence of chloride concentration on the extraction rate of copper (II) by LIX 65N HS diluted with ESCAID 100 has been determined experimentally. The extraction rate is maximum at an intermediate chloride concentration. Adopting an interfacial mechanism in which the formation of the complex CuR 2 is the rate controlling step, this phenomenon may be explained assuming that both CuCl + and Cu 2+ cupric ions are engaged in the extraction process. The thermodynamic model, the parameters of which were obtained independently from various equilibrium data, is applied to the evaluation of the concentrations of cupric chlorocomplexes and of their activity coefficients in the aqueous phase which are useful in obtaining kinetics in terms of activities.

Influence of chloride concentration and pH on the 36Cl efflux from depolarized skeletal muscle of Rana temporaria.

1. 36Cl- efflux rates were measured in depolarized fibre bundles (predominantly fast fibres) from m. semitendinosus of Rana temporaria in order to investigate the influence of chloride concentration (20-400 mM) and external pH (pHo, 5.5-11.6) on chloride self-exchange. Usually, the bundles were depolarized to a membrane potential of virtually zero ([Cl-]i = [Cl-]o = [Cl-]) in 140 mM-K+ and 20 mM-Cl- combined with either 60 mM-SO4(2-) (+52 mM-sucrose) or 120 mM-methyl sulphate, gluconate or glucuronate. Various values of [Cl-] were obtained by adding KCl to the medium, keeping constant the concentration of relatively impermeant solutes and thus the fibre volume. 2. The chloride permeability, PCl, at pH 7.5 decreased with increasing [Cl-] above 50 mM. At [Cl-] less than 50 mM, PCl was about 4 X 10(-6) cm s-1. 3. PCl at pHo 7.5 and 5.6 was a hyperbolic function of [Cl-1] (greater than or equal to 50 mM), consistent with saturation kinetics of chloride self-exchange. 4. Methyl sulphate inhibited chloride self-exchange and may enter depolarized fibre membranes slowly. Comparison of PCl estimates in SO4(2-), gluconate, and glucuronate suggested that SO4(2-) and gluconate may interfere with chloride self-exchange at low [Cl-], and that glucuronate interferes the least. 5. A change from chloride equilibrium to an inward KCl gradient increased the 36Cl- efflux rate in acid media (pH less than 6.5) and decreased the efflux rate at pHo greater than or equal to 7. The effects were not due to changes of membrane potential and demonstrate a change of transport mode consistent with single-filing at high pH and dominant exchange diffusion at low pH. This result makes interpretation of the saturation kinetics difficult. 6. At constant [Cl-], PCl showed a bell-shaped dependence on pHo with a maximum around pH 8.5. The decrease of chloride permeability as the pH is decreased below 8.5 showed an apparent pK of about 7. PCl fell at very alkaline pH with an apparent pK of about 10. 7. The results are in agreement with previous observations of an external pH-sensitive control of PCl (pK approximately 7) and suggest that, in conditions close to chloride equilibrium, this control includes a transition between a dominant conductive channel conformation at high pH and a dominant non-conductive conformation at low pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Influence of Chloride Concentration on Stress Corrosion Cracking of Austenitic Stainless Steel in LiCl Solutions

Abstract At constant temperature, the corrosion potential of Type 304 stainless steel in LiCl solutions is independent of Cl− concentration over the range of 2.5 to 11.8 N, whereas, the cracking potential becomes more noble with decreasing concentration. This reduction in the polarization of Ecor relative to ECC is a primary factor responsible for the influence of Cl− concentration on time to failure at the open circuit potential. The corrosion and cracking potentials are independent of temperature at constant Cl− concentration. Failure time decreases with increasing temperature; however, the thermally activated process responsible for this behavior has not been identified. Stress induced film rupture leads to trench corrosion, and stress corrosion cracks subsequently evolve from these trenches.

Stress corrosion cracking of type aisi 304 stainless steel at room temperature; influence of chloride content and acidity

The influence of chloride concentration and acidity on the occurrence of stress corrosion cracking (s.c.c.) of type AISI 304 austenitic stainless steel at room temperature has been studied. The results obtained show that s.c.c. in acidic chloride solutions can occur in a wide range of acidity as a function of the total chloride content. Cracking occurs in the active potential range.

The Influence of Chloride Concentration on the Kinetic Behaviour for the Initiation Stage of pitting corrosion on aluminium

AbstractExperiments are performed to study the influence of applied potential and chloride concentration on the kinetic behaviour of pitting corrosion initiation for unalloyed aluminium. A potentiostatic method is used at 30°C in deaerated solutions of sodium chloride. The pitting potential, Ep, is determined by the extrapolation method described by Broli, Holtan and Midjo, and a relation between Ep and chloride concentration is found. Kinetic interpretations such as the influence of applied potential and chloride concentration on the induction time are given.

Water Treatment: An Account of Work at the Former National Chemical Laboratory

AbstractIn the work of the National Chemical Laboratory on the control of corrosion in waters special attention has been paid to the influence of chloride concentration, flow rate and temperature, and the need to obtain corrosion/time curves over periods of weeks has been demonsrrated. Treatment with metaphosphate in combination with calcium or zinc ions has been shown to be very effective even in solutions containing 2,500 ppm of sodium chloride. Much research is needed to develop inhibitive mixtures to protect combinations of dissimilar metals at temperatures up to 200° temperatures up to 200°.