Effective corrosion inhibition of mild steel in an acidic environment using an aqueous extract of Macadamia Nut Green Peel biowaste
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Date
2022-12
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Improving the corrosion resistance of mild steel in an acidic aqueous environment is an
important industrial consideration due to the use of acids for descaling and cleaning. The application
of corrosion inhibitors is one of the most effective and economical means of protecting metals against
corrosion. Plant-derived compounds have recently gained attention due to their low cost, non-toxic,
and environmentally friendly properties. Biowastes are recognized as a potential cheap source
of green corrosion inhibitors, and their use can help to lower the costs associated with corrosion
inhibitors. Green peel biowaste (GPBW) generated from macadamia nut processing is typically
dumped into the environment, posing a disposal concern. The use of the waste as a potential source
of organic compounds with green chemistry attributes for mild steel corrosion inhibition in an acidic
solution was proposed in this study. The gasometric and optical methods were used to carry out the
investigations. Results showed that mild steel corrosion rates decreased as extract concentrations
increased. As a result, mild steel corrosion inhibition increased with increasing inhibitor concentration
and reached a peak value of 81% at 0.5 g/L extract concentration. The optical images showed that the
inhibitor molecules adsorbed on the metal surface to form a protective film that isolated the mild steel
from the corrosive solution. The adsorption of inhibitor molecules on the mild steel surface followed
the Langmuir adsorption isotherm, indicating the formation of a monolayer film with a homogeneous
distribution of adsorbed molecules. A Gibbs free energy (G◦ ads) of 24 kJ/mol indicated the inhibition
process was mainly characterized by physical adsorption. The results of this study suggest that
aqueous GPBW extract could serve as an inexpensive, non-toxic, and renewable corrosion inhibitor
of mild steel in acidic solutions.
Description
Proceeding Paper
Keywords
corrosion inhibition, macadamia green peels, biowastes, green chemistry, mild steel, acidic solution
Citation
Mwakalesi, A.J.; Nyangi, M. Effective Corrosion Inhibition of Mild Steel in an Acidic Environment Using an Aqueous Extract of Macadamia Nut Green Peel Biowaste. Eng. Proc. 2023, 31, 41. https://doi.org/ 10.3390/ASEC2022-13804