Box-Behnken design to enhance the corrosion resistance of high strength steel alloy in 3.5 wt.% NaCl solution

Recently, the production of green corrosion inhibitors and green inhibition strategies is highly demanded in the field of science and technology due to the growing demand of green chemistry. Usage of plant extracts as metallic corrosion inhibitors has attracted considerable attention in the last few decades. Plant products are perfect green candidates for replacing traditional toxic corrosion inhibitors. Reduced environmental risk, lower cost, widespread availability and high corrosion inhibition efficiency make plant extracts ideal candidates for the substitution of costly and harmful traditional synthetic corrosion inhibitors. An aqueous extract of plant material Henna (Lawsonia Inermis) powder was used as a corrosion inhibitor to control the corrosion of high strength steel immersed in an aqueous solution containing 35000 ppm Cl-, by electrochemical methods in the absence and presence of the inhibitor. Lawsone is the principal constituent of this plant extract. This has excellent efficiency in inhibition and displays excellent IE at neutral pH. Electro-chemical experiments such as potentiodynamic polarization and impedance were used to describe the mechanistic aspects of corrosion inhibitions. Box-Behnken method was used to investigate the effect of key parameters (i.e. concentration of inhibitors, temperature, and speed of rotation) on the efficiency of inhibition and corrosion rate of high strength steel alloy in 3.5 wt.% NaCl solutions. From electrochemical measurements and statistical analysis, it was found that the efficacy of inhibition improves with higher inhibitor concentration, low rotation speed and low temperature. The Lawsonia Inermis extracted demonstrated strong corrosion inhibition in saline media for high strength steel alloy and reached 81.68.