Electrodeposition of organic corrosion inhibitor prepared from eucalyptus robusta leaves

Abstract

Eucalyptus Robusta leaves were used as raw material to develop a steel corrosion inhibitor. A straightforward approach was employed to extract organic molecules from Eucalyptus Robusta leaves, which were applied as a protective coating on steel surfaces to inhibit corrosion. The solution containing the organic inhibitor was electrodeposited onto the surfaces of ASTM A36 steel samples, and an investigation into the parameters of charge (positive or negative), voltage (5 or 20 V), and time (5 and 30 min) was conducted through a 23 factorial experiment. Electrodeposited wet and dry samples had their open circuit voltage (OCP) measured in an acid solution and compared with the OCP of samples in which the inhibitor was deposited by simple immersion (deposited samples) and samples without inhibitor (blank samples). All the samples that had contact with the inhibitor increased their OCP values, showing the effectiveness of the deposition of the inhibitor. Nevertheless, the electrodeposition process carried out for 30 min and with a positive charge (anodic) proved to be the most effective in increasing the OCP value. Optical and scanning electron microscopy analyses revealed that the inhibitor solution effectively formed a thin, uniform, compact film on the metal surface. However, occasional deposition anomalies resulted in the formation of protrusions with organic material accumulation. Electrochemical Impedance Spectroscopy and Tafel curves were used to evaluate the effectiveness of the organic inhibitors. Accelerated corrosion tests in an HCl solution indicated reduced corrosion and the formation of distinct corrosion products for samples with an inhibitor compared to a sample without an inhibitor.