Papers by Keyword: Chloride Ion

Abstract: This study investigates the stress corrosion cracking (SCC) behavior of Aluminum in chloride solutions, focusing on varying bending angles (0°, 90°, and 180°), temperatures (25°C, 35°C, and 45°C), and NaCl concentrations (1%, 2%, and 3.5%). Bending tests using a universal testing machine and corrosion tests employing the open circuit potential (OCP) method and anodic polarization Tafel method were conducted. Results revealed that the highest balanced potential (-0.33684 V) occurred at a 0° bend angle in distilled water, while the lowest (-1.02513 V) was at a 180° bend angle in 3.5 wt% NaCl solution. The lowest corrosion rate (0.002403953 mmpy) was observed at a 0° bend angle in distilled water at 25°C, and the highest (2.18789227 mmpy) at a 180° bend angle in 3.5 wt% NaCl solution at 45°C. Surface characterization indicated significant pitting corrosion in NaCl solutions, particularly at a 180° bend angle, while no pitting was seen in distilled water. These findings highlight the substantial impact of bending angle and chloride concentration on the SCC behavior of Aluminum, providing valuable insights for its application in corrosive environments.

Abstract: Full functioning of wells in oil and gas fields is impossible without the use of tubing. Main function of tubing is transportation of gases and liquids produced in productive zone to well surface. In addition, tubing acts as a kind of insulator that protects the gas and liquid transported through them from the walls of the well, and also prevents the occurrence and development of corrosion, deposits of paraffin and asphaltene on casing pipes. The tubing pipe placed in the well is also necessary in order to ensure the carrying out of downhill and repair work, which is regularly necessary. Standard tubin g (tubing) as a result of technological difficulties does not undergo a strengthening operation. When manufacturing tubing and locks to them from alloyed steels, the main attention is paid to improving mechanical properties, which is achieved by thermal and chemical-thermal treatment. However, the practice of operating tubing shows that the introduction of these measures does not solve the issue of reliability, since threaded connections for the coupling and nipple remain vulnerable sections of tubing. Tubing (tubing) during its operation experiences significant loads and is in constant contact with aggressive media, which leads to serious requirements for their quality. The possibility of replacing its production from alloyed steels with aluminum alloys, for example, AlCuMg₂ will facilitate the design by 2.5 times, prevent the tendency to stress corrosion cracking (SCC) in a hydrogen sulfide-containing medium and eliminate inhibitory protection. The main disadvantage of aluminum alloys is the tendency to pitting corrosion. It is possible to improve the protective properties of the passive film on aluminum alloys by anodizing.

Abstract: A simple, low cost and rapid analytical method for determination of HCl concentration after being treated with cellulose and cellulose nanofibers (CNF) is developed. This method is based on color intensity after the HCl solution is doped with sodium iodide (NaI). The color of HCl solution changes from colorless to yellow. The intensity of the color is measured by UV – Visible spectroscopy. The UV-Visible spectra of 0.15 M HCl treated with cellulose and cellulose nanofibers is reduced from its initial concentration. The CNF absorption capacity is higher as compared to cellulose. FT-IR analysis showed that there is interaction between C-H group from the CNF backboned and chloride ion from HCl solution.

Abstract: Nicosulfuron is a kind of sulfonylurea herbicide used for controlling weeds in corn. In order to solve the problem of plant water with agrochemical, electrolysis was investigated for the treatment of nicosulfuron from dilute aqueous solutions. The operating varieles of time, chlorine anion, pH were experimented and the electrolytic decomposition mechanism of nicosulfuron was suggested. Acid solution was effective for the decomposition of the nicosulfuron and the existence of chloride ions lead to the formation of electrolytic reaction products, which regarded as chloronicosulfuron by HPLC-MS. The reaction is similar to free radical reaction.

Abstract: A series of mesoporous silica materials (SBA-15, MCM-41, KIT-6) with different pore structures and properties were synthesized and characterized by means of small angle X-ray scattering, transmission electron microscopy, infrared spectroscopy and nitrogen adsorption-desorption. The adsorption properties of three mesoporous silica materials for chlorine ions in aqueous solution were investigated. The results show that SBA-15, MCM-41 with two-dimensional hexagonal structure has a better adsorption effect on chloride ion than KIT-6 With cubic core structure, and MCM-41 with larger specific surface area and smaller pore size has better adsorption effect on chloride ion than on SBA-15. The specific surface area of MCM-41 is 1036 m²/g, and the The adsorption kinetics accords with the pseudo-second-order kinetic model, and the adsorption isotherm is more consistent with the Langmuir isotherm model. The optimum operating conditions for MCM-41 to adsorb chloride ions are as follows: temperature 55 °C, pH 6, adsorption time 2 h, Cl^- concentration 0.01 mol/L (584 mg/L) and adsorbent concentration 1.0 g/L. Under these conditions, the adsorption capacity of MCM-41 to chloride ions is greatly enhanced, and the maximum adsorption capacity is 188.18 mg/g.

Abstract: Using magnesium nitrate, nickel nitrate and aluminum nitrate as raw materials and urea as precipitant, magnesium nickel aluminum ternary hydrotalcites with large specific surface area were prepared by hydrothermal method. The prepared samples were characterized by SEM、XRD、BET and EDS etc., respectively. The adsorption properties of MgNiAl-LDHs, MgAl-LDHs and their calcined products (MgNiAl-LDOs, MgAl-LDOs) for chloride ions in solution were investigated. The results show that MgNiAl-LDHs are cubic with rod-like structure, with a specific surface area of 197.62 m²/g, which is much larger than that of MgAl-LDHs (102.82 m²/g). Under the same adsorption conditions, the saturated adsorption capacities of MgNiAl-LDHs and MgAl-LDHs for chloride ions are 130.06mg/g and 110.02 mg/g respectively. MgNiAl-LDOs showed better adsorption ability for chloride ions. By simulating the adsorption data, the results show that the adsorption kinetics and the adsorption isotherm are in accordance with the quasi-second-order kinetic model and the Langmuir isotherm model, respectively.

Abstract: Magnesium-aluminum hydrotalcite and carbon nanotube composites (CNTs/MgAl-LDHs) were prepared by one-step hydrothermal method using magnesium nitrate, aluminum nitrate and carbon nanotubes as raw materials and urea as precipitant. The samples were characterized by SEM, XRD, BET and other methods. The adsorption properties of CNTs/MgAl-LDHs on chloride ions and the factors affecting the adsorption of chloride ions were studied. The results show that the prepared CNTs/MgAl-LDHs exhibit a three-dimensional honeycomb structure with a specific surface area of 103.019 m²/g, which is larger than the specific surface area of MgAl-LDHs of 84.344 m²/g. The results showed that the optimal adsorption conditions were: adsorption temperature was 45°C, the pH value was 8, the adsorption time was 100 min, the Cl^- concentration was 0.01 M (584 mg/L), and the adsorbent concentration was 1.0 g/L. CNTs/MgAl-LDHs has the best adsorption performance for chloride ions. The maximum adsorption capacity is 75.58 mg/g. The adsorption isotherms and adsorption kinetics are consistent with the Langmuir isotherm model and the quasi-secondary kinetic model.

Abstract: The effects of chloride ion concentration on SCC susceptibility of 15Cr and 13Cr martensitic stainless steels were investigated at 180°C by SSRT. Transgranular SCC occurred in the environment containing CO₂ and chloride ion. The increasing chloride ion concentration was significantly affected SCC susceptibility of 15Cr SS. In addition, the contribution of hydrogen to SCC was examined at high temperature by SSRT with electrochemically polarization. The cathodically charged specimens showed hydrogen embrittlement. The fracture surface was similar to that of high temperature SCC. On the other hand, the SCC was accelerated by anodic polarization and not by cathodic polarization. The SCC behavior of martensitic stainless steel at high temperature is affect by evolved hydrogen atom. It is concluded that hydrogen plays a key role in the crack propagation.

Abstract: As one of the leading causes of influencing the durability of concrete structure, reinforcement corrosion has been a central issue. Erosion of chloride ions on the concrete structure is influenced by many factors. This is not only concerned with its own structural properties, but also to its environment, to withstand the load and other factors. This article has carried on an experiment which researches on the rules of chloride ion penetration in the sustained axial compression after different corrosive time, when the concrete is corroded under the joint action of axial compression load and chlorine salt circulation. The results prove that, with the increase of Intensity of load and the cycle time of chlorine salt, the number of Chloride ion ingress in concrete continues to increase. The experimental results may provide a reference to the durability design of concrete in chloride environment.

Abstract: The influence law of permeability of chloride ion in concrete of load level, curing condition under the sustained pressure load and the corrosion environment interaction is researched in this article, which is through natural diffusion method. Experimental results show that as the load level increases, there is a tendency of the chloride ion content after the first increase and then decrease, the turning point in the middle remains to be further studied. Good conservation condition reduces large holes and harmful holes in concrete block, thereby reduce the porosity and improve resistance to chloride ion erosion.