Trachyspermum Leaves Extract as a Green Inhibitor for Corrosion Inhibition of Mild Steel in 0.1m HCl: Experimental and Computational Study

The present study aims at investigating the impacts of the extract of Trachyspermum leaves on the mild steel corrosion in 0.1M hydrochloric acid (HCl), while highlighting its inhibitory mechanisms. The effects of mild steel corrosion in solutions of HCl were examined using the gravimetric and galvanostatic polarization techniques, along with EIS analyses. According to the results, the maximum inhibitory effectiveness corresponding to the minimum corrosion rate could be observed at the highest desirable level of inhibitor concentration equal to 100 ppm, while the corrosion rate decreases with an increase in the extract concentration. The absorption examinations indicated the best description of the metal surface interaction by Langmuir isotherm, while obtaining the best exposure time for the Trachyspermum leaves extract adsorption into the surface of the metal in different concentration. Based on the results of polarization, the inhibitors can play the role of a mixed inhibitor, also confirmed by the computational data.

Study of Steel Electro-dissolution Behavior in Presence of Some Surfactants. Electrochemical Investigation and Surface Active Properties Determination

Steel electro-dissolution performance was investigated in orthophosphoric acid in the presence of N-oleyl 1.3 diaminopropane, Benzalkounuim chloride, Soduim lauryl sulphate and Di-Isononyl phthalate as a surfactant using potentiodynamic polarization measurements. The retardation performance of these surfactants was examined. The surfactant surface active parameters were estimated based on surface tension measurements. The parameters calculated comprise the critical micelle concentration (CMC), maximum surface excess (Гmax), minimum surface area (Amin) and effectiveness (πCMC). The micellization thermodynamic parameters (ΔGmic, ΔSmic) for the estimated surfactants were also computed. Results obtained from surface active properties are comparable with those gained from galvanostatic polarization measurements. Temperature influence on the steel dissolution performance was examined at 25 to 40oC range. Steel kinetic study in orthophosphoric acid- free solution and orthophosphoric acid containing surfactant was also examined. The dissolution kinetic and activated parameters were computed. Results based on microscopy measurement indicate that, addition of new four surfactants, resulting in the solution shows potential, a discrete progress in the metal texture was monitored. Improvement produced in electro-polishing bath by the investigated SAS that owing to the adsorption of such surface active agents on the anode surface.

The Electropolishing of C-Steel in Orthophosphoric Acid Containing Methanolic Plant Extract

Plant extracts have been regarded as “green” alternatives as additives for metal electropolishing improvement. Therefore, understanding the electrochemical properties and the reaction mechanisms of the electroactive compounds from the plant extracts is necessary to further explore the mechanism and application of the plant extract-based additives for metal dissolution. The C-steel electropolishing behavior in orthophosphoric acid using the galvanostatic polarization and weight loss methods was ascertained. This was inspected via anode potential-limiting current relationship measurement and comparison in a solution of regularly mounting concentrations (from 50 to 1800 ppm of methanolic marjoram, coriander seeds, chamomile, and guava leaves extract), and the influence of temperature on the dissolution kinetics was investigated. Surface morphologies, roughness, and reflection of investigated specimens were inspected with a scanning electron microscope (SEM), profilometry, and Vis-IR spectroscopy. Addition of methanolic plant extract to the electropolishing solution results in a lower limiting current. Retardation percentage gained from mass loss measurement is comparable with those obtained from measurements of galvanostatic polarization. Addition of 500 ppm of marjoram, coriander, chamomile, and guava leaves increases the degree of surface brightness and reflectance to 64.9, 56.59, 27, and 24.5, respectively, relative to electropolishing electrolyte-free solution 16. The roughness (Ra) decreased from 2.7 μm to 0.52 μm without addition of any material. Ra values are 0.28, 0.23, 0.21, and 0.17 μm in the presence of guava leaves, chamomile, coriander seeds, and marjoram.

Study of corrosion behavior of virgin and recycled Pb anodes used in zinc electrowinning industry

Purpose The composition and corrosion behaviors of recycled and virgin Pb anode were investigated in industrial zinc electrowinning solution with different methods. The purpose of this study is the illustration of good anticorrosion activity of virgin Pb anodes compared to recycled one in industrial operation, while the compositions of both of them are the same which obtained from quantmetry method. Design/methodology/approach Its corrosion properties and electrocatalytic activity toward oxygen evolution reaction were appraised using potentiodynamic polarization, electrochemical impedance spectroscopy, galvanostatic polarization and ionic equilibrium methods. In addition, composition of anodes investigated with X-ray photoelectron spectroscopy (XPS) method. The surface composition of samples was studied via X-ray diffractogram (XRD). Findings The results indicate that the anodes display different anodic behaviors during the galvanostatic polarization. Virgin Pb anode shows a “potential reduction” about 320 mV lower than recycled Pb anode after 6 h of polarization; also, the stable potential after 72 h for virgin Pb anode is 100 mV lower than recycled Pb anode. Also, The XPS results show a trace amount of Cl in recycled anodes which cause the more corrosion activity. XRD results indicate that virgin Pb anodes have been covered by more oxides than recycled anodes after 72 h of electrowinning. Originality/value The treatment of corrosion behavior by virginity has not been detected by any researchers yet. Therefore, it is imperative to study the corrosion behavior and exact composition analysis of virgin and recycled Pb anodes to comprehension of them. This paper fulfills this need.

Electrochemical Performance of Steel Embedded in CSA Concrete and Its Interfacial Microstructure

Calcium sulfoaluminate cement (CSA) is a low-carbon cementitious material that significantly reduces alkalinity and produces calcium hydroxide-free (CH-free) matrix environment in comparison to ordinary Portland cement (OPC). It might be, however, less efficient towards the passivation of steel in concrete and further investigation before widespread adoption is required. In this project, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) on polished samples was employed to provide the interfacial characterization of steel reinforced CSA concrete and study the relationship of interfacial quality and corrosion resistance of the embedded steel. The galvanostatic polarization behavior indicates that the steel embedded in CSA concrete remains passive for 28 days in absence of Cl− ions and carbonation. Microstructure analysis has shown that there is an Al-enriched layer at interfacial zone in CSA concrete with the main hydration product of AH3, which is also alkaline and is expected to improve the steel passivity. Furthermore, the interfacial zone has markedly reduced porosity compared to the bulk matrix, which leads to reduced possibility of current flow between anode and cathode and therefore improves the corrosion resistance of the embedded reinforcement.