Abstract
Investigation into the Inhibition of pitting corrosion in mild steel around heavy salt deposits by some selected secondary plant metabolites—alkaloid extract (AESML), saponin extract (SESML and flavonoid extract (FESML) of natural product origin—Strongylodon macrobotrys was successfully completed with the aid of electrochemical impedance spectroscopy, potentiodynamic polarization, gravimetric and gasometric experimentation. The research proved that the selected secondary plant metabolites were excellent inhibitors of mild steel in the salt water environment as inhibition efficiency was recorded at 99.2%, 92.6% and 84.7% for AESML, SESML and FESML. The inhibitors showed higher inhibition at lower temperature due to frequent scale redeposition from agitation in temperature rise and loss in collision of the molecules. The potentiodynamic polarization result confirmed the reduction in the loss of electrons at the anode by the inhibitors that would have trigger oxidation reaction that causes the anode to corrode. Charge transfer resistance reflected the maximum inhibition efficiency obtained for mild steel at maximum concentration and the decrease in double layer capacitance is due to the decrease of the area where electrolyte is present due to the formation of inhibitor film. Thermodynamic investigation shows that the inhibitor has the potential of increasing the energy of the intermediate, reducing both the number of collisions, and number of particles that have enough energy to react and also number of corrosion reaction particles with the correct orientation. The adsorption isotherm consideration shows physical adsorption mechanism with binding constant increasing with increasing temperature.
Highlights
Corrosion is the world’s most destructive factor of materials most importantly metals, and one very important factor that slows the advancement of industrialization and economic advancement
The research proved that the selected secondary plant metabolites were excellent inhibitors of mild steel in the salt water environment as inhibition efficiency was recorded at 99.2%, 92.6% and 84.7% for AESML, SESML and FESML
Secondary plant metabolites of natural products ranging from alkaloids, tannins, flavonoids, saponins, terpenes, glycosides, etc. are well known to possess to a larger extent some hetero atoms like sulphur, phusphorus, nitrogen, and aromatic tendencies, presence of pi and sigma bonds, etc. that have a strong binding tendency on surfaces and the ability to displace water molecules concentrated on such surfaces creating an interface that disallows the action of corrosive substances on such surfaces [2] [13] [14] [15]
Summary
Corrosion is the world’s most destructive factor of materials most importantly metals, and one very important factor that slows the advancement of industrialization and economic advancement. The struggle to combat corrosion effects on materials especially metals has come a long way ranging from the use of different protective measures especially environmental modifications, metal selection and surface conditions, cathodic protection, coating, plating to the use of synthesizes inorganic materials that became unhealthy to the environment after usage, and eco-friendly secondary plant metabolites of natural product [4] [5] [6] [7]. Secondary metabolites are chemicals produced by plants for which no role has yet been found in growth, photosynthesis, reproduction, or other primary functions [8] [9] They can be classified on the basis of chemical (for example, having rings, containing a sugar), composition (containing nitrogen or not), their solubility in various solvents, or the pathway by which they are synthesized. It is an evergreen climber commonly known by the name emerald vine and very dominant in Gabu forest
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
