Corrosion resistance effect of aluminium steel in 1N sodium hydroxide by an aqueous extract of Thespesia populnea plant leaves has been investigated by mass loss method. It is observed that as the concentration of the inhibitor increases, the inhibition efficiency increases. The mechanistic aspects of corrosion resistance have been studied by potentiodynamic polarization technique and electrochemical impedance spectroscopy. A maximum inhibition efficiency of 78.70% is achieved by this inhibitor system. Potentiodynamic polarization technique reveals that the inhibitor system functions as a mixed type of inhibitor, controlling anodic and cathodic reactions. It is noted that in the presence of inhibitor, linear polarization resistance value increases and corrosion current decreases. Electrochemical impedance studies reveal that a protective film is formed on the Al steel surface, since in the presence of inhibitor system, the charge transfer resistance value increases and double layer capacitance value decreases. This is due to adsorption of the molecules of the active ingredients of the extract on the Al steel surface. The inhibition efficiency increases due to adsorption of hetero atoms present in TP plant leaves extract on the Al steel surface. The maximum inhibition efficiency and the lower corrosion rate are obtained at high concentration 1200 ppm for TP plant leaves extract. By further increase in inhibitor concentration above 1200 ppm, the inhibition efficiency and corrosion rate almost remained constant. So, the 1200 ppm concentration is fixed as the maximum inhibition for the investigative aqueous extract of plant leaves as corrosion inhibitor. This concentration corresponds to the attainment of a saturation value in surface coverage of Al steel. The protective film formed over the Al steel surface has been characterized by Fourier Transform infra-red spectroscopy. The surface morphology of the protective film of carbon steel immersed in sodium hydroxide in the absence and presence of inhibitor has been studied by Scanning electron microscopy. The outcome of the study can be used in pickling industry wherein sodium hydroxide is used to remove the rust on the Al steel surface.

A kind of tropical hardwood tree called the Tectona grandis tree that is indigenous to India. The name "teak tree" is another common name for this kind of tree. It is a member of the plant family that is referred to as Lamiaceae. The primary purpose of this research is to investigate whether or not the plant extract has a corrosion-inhibiting quality. In this study, an aqueous extract of Tectona grandis leaves, commonly known as TGLE, was employed as a corrosion inhibitor for aluminium (Al) in a solution of sodium hydroxide with a concentration of 1M. The sodium hydroxide solution was prepared by diluting 1M sodium hydroxide with 1M sodium hydroxide. Electrochemical methods, such as Potentiodynamic polarisation (PDP) and Electrochemical Impedance Spectroscopy (EIS), in addition to chemical methods, were used in this study to evaluate the inhibitory effects of this medication (weight loss). A promising inhibitory efficiency (IE) of 80% was achieved with TGLE when it was administered at an optimal dosage of 1.2 g/L; this was found to be consistent across all of the techniques that were used. The results of the trials were combined into an appropriate adsorption isotherm, which allowed for additional study into the inhibitor's method of action to be carried out. In order to investigate the possible influence that temperature may have on the effectiveness of the inhibitor, a temperature range of 303 to 333 degrees Kelvin was investigated. An inquiry of the surface was carried out using microscopic metallurgical research, and the results of this study provided further support for the findings.

In the present work, the effect of Mimosa pudica leaves extract on the corrosion of aluminium in 1N NaOH was studied using weight loss measurements and electrochemical techniques such as Tafel Polarization and Electrochemical Impedance Spectroscopy. A maximum inhibition efficiency of 78% is observed at 1.2g/L of inhibitor concentration which was found to be consistent across all the methods employed. The temperature dependency inhibitive properties of the selected inhibitor were studied in the range 303- 333K. The adsorption behavior of the inhibitor on the surface of aluminium was studied by fitting Langmuir adsorption isotherm and the nature of adsorption was found to be physisorption. Metallurgical microscopic analysis of the aluminium surface with and without the inhibitor further validated the results.