Abstract
This work investigates the synergistic use of Theobroma cacao (Cocoa), and Elaeis guineensis (Palm oil) as corrosion inhibitors for carbon steel in 0.5 mol.L-1 hydrochloric acid solution, in the absence and presence of different mixture concentrations of the studied compounds. The efficiency of corrosion inhibitors was studied by gravimetric tests and the corrosion resistance by electrochemical tests, such as electrochemical impedance spectroscopy (EIS) and polarization curves. The chemical composition of the cocoa bark powder and palm kernel cake powder was evaluated by Fourier transform infrared spectroscopy (FTIR). The results of the gravimetric tests showed an inhibition efficiency of 79% for the cocoa bark powder and 76% for palm kernel cake powder, however, the mixture of the compounds presented an inhibition superior to 94%, showing the great synergism between the studied species. These results corroborate the values obtained from EIS.
Highlights
The corrosion in metallic surfaces has become a relevant problem for society, which represents a big material and economic waste, falling upon a relevant phenomenon that affects the chemical, petrochemical, naval, civil construction, automotive, aerospace, white line, and communication sectors, among others, causing environmental and economic impacts 1
The study by the National Association of Corrosion Engineers (NACE) estimated that the global cost of corrosion was US$2.5 trillion per year, which is equivalent to 3.4% of the global Gross Domestic Product (GDP) 2
Through the analysis of the results, it was possible to conclude that the cocoa bark powder (CBP) and palm kernel cake powder (PKCP) both presented the required potential to be used as corrosion inhibitors for ASTM 1020 carbon steel in 0.5 mol.L-1 HCl solution
Summary
The corrosion in metallic surfaces has become a relevant problem for society, which represents a big material and economic waste, falling upon a relevant phenomenon that affects the chemical, petrochemical, naval, civil construction, automotive, aerospace, white line, and communication sectors, among others, causing environmental and economic impacts 1. The study by the National Association of Corrosion Engineers (NACE) estimated that the global cost of corrosion was US$2.5 trillion per year, which is equivalent to 3.4% of the global Gross Domestic Product (GDP) 2. The cost is an important aspect of the fight against corrosive processes, and with the advancement of technology, the demand for corrosion-resistant products is significant. Coatings and corrosion inhibitors are used to minimize the effects of corrosion. Some synthetic corrosion inhibitors have toxic properties that are harmful to the environment and human health. In this context, the use of natural inhibitors is beneficial both financially and environmentally, due to their biodegradability, ecological acceptance, and renewability 3
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