Abstract
Abstract The present work aims to study the aqueous cotton seeds extract as a natural inhibitor of the corrosion of mild steel in 1 mol L−1 HCl using gravimetric tests, potentiodynamic polarization curves, electrochemical impedance measurements and surface morphological analysis by scanning electron microscopy (SEM). The aqueous cotton seed extract acted as a good corrosion inhibitor reaching an inhibition efficiency of 95.7% after 24 h of immersion for 800 mg L−1 inhibitor concentration. For the gravimetric tests varying the temperature, a decrease of the activation energy (Ea) was observed, suggesting a chemical adsorption on the surface of the metal. 400 mg L−1 of the high molecular weight fraction isolated from the total extract showed inhibition efficiency equal to 800 mg L−1 of the total extract, 97.3% and 94.2% from electrochemical impedance and polarization curves data, respectively, suggesting that the macromolecules present a fundamental participation in the inhibitive process.
Highlights
Corrosive processes are directly or indirectly linked to our daily lives
We have studied the inhibitory action of some aqueous oilseed extracts like castor beans and soybean meal extracts towards the mild steel corrosion in acidic media. 800 mg L−1 aqueous castor beans and soybean meal extracts showed inhibition efficiency of 94.4 and 88.8%, respectively, from weight loss data after 2 h immersion[23,24]
IE values increases with temperature, indicating an adsorption process of chemical nature, where organic molecules from the extract adsorb on the steel surface involving charge sharing or transfer from the inhibitor molecules present in the aqueous cotton seeds extract (ACSE) to the mild steel surface, having IE percentages varying from 82% to 89% in the temperature range of 25 °C to 55 °C, respectively
Summary
Corrosion is a problem present in many places, such as industries, buildings, viaducts, as well as ancient and modern works of art[2]. In this scenario, new studies are developing more sustainable methods, such as inhibitors, to control the effects of corrosion causing less damage to the environment. The application of corrosion inhibitors is one of the most used and effective methods found in the literature[3]. Inexpensive, and environmentally friendly products have been used for corrosion control[4,5,6,7,8,9,10,11,12,13]
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