Abstract
The corrosion inhibition of 1018 carbon steel in 0.5 M H2SO4 by using Actinidia deliciosa (Kiwifruit) peel extract has been investigated by using potentiodynamic polarization curves and electro-chemical impedance spectroscopy. Two kinds of extracts are investigated, one from the tender, and another one from ripe Actinidia deliciosa. Concentrations include 0, 25, 50, 75, and 100 ppm at room temperature. Results indicate that both kind of extracts acted as good corrosion inhibitors, is more efficient in the ripe extract. Corrosion inhibition efficiency increases with increasing its concentration for ripe extract, whereas for the tender Actinidia deliciosa, the higest inhibitor efficiency is obtained by adding 25 ppm and decresaing with a further increase in its concentration. Both extracts improve the passive film properties by decreasing the passive current density values. It is found that the corrosion inhibition is due to the presence of heteroatoms present in Actinidia deliciosa, mainly quercitine, which is physically adsorbed in the steel following a Frumkin type of adsorption isotherm which forms a protective film.
Highlights
The use of corrosion inhibitors is one of the most widely methods to fight corrosion [1]
0.5 M H2SO4 is shown in Figure 1 where it can be seen that, for the uninhibited solution, polarization curve displays an active-passive behaviour, with the anodic current density increasing as the applied potential increases, up to a potential value where the current density decreases abruptly, reaching a passive current density value, Ipas, which remains more or less constant, around 0.5 mA/cm2, up to a potential value, the pitting potential or Epit, 1290 mV, where the current density values suddenly increases once again
Anodic and cathodic Tafel slopes remained more or less constant up to an inhibitor concentration of 50 ppm, but both of them were drastucally increased with the addition of either 75 or 100 ppm, indicating that Actinidia deliciosa is acting as a mixed type of inhibitor, affecting both anodic and cathodic reactions
Summary
The use of corrosion inhibitors is one of the most widely methods to fight corrosion [1]. Synthetic inhibitors has many disadvantages such as damage to the environment, toxic to humans and other living expensive species among others [2] This is the reazon why in the last years there has been an increasing interest in naturally ocurring inhibitors and has motivated many researchers to focus on the need to develop cheap, non-toxic and environmentally benign natural products such as leaves, fruits or seeds extracts, which can be used as corrosion inhibitors. The reason of this is the presence of complex organic species such as tannins, phenosl, alkaloids, carbohydrates and proteins as well as their acid hydrolysis products [3]-[10]. The use of these natural products is more effective and highly environmentally benign compared to organic and inorganic inhibitors used in chemical or any industrial applications
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