Tribulus terrestris Extracts: An Eco-Friendly Corrosion Inhibitor for Mild Steel in H2SO4 Medium

Abstract

INTRODUCTIONThe use of mild steel in industries is due to its availability, good strength and comparatively low cost. The overall cost of metal is the total cost of itself plus its maintenance cost and it can be reduced by reducing the maintenance cost. The maintenance cost can be controlled and minimized. But presently in all countries, most of the industries are facing the problem of corrosion of mild steel in acidic medium [1]. It involves a significant cost expense for prevent or non-prevent of the metals. On the one hand if protection methods are not used, the maintenance and renovation cost will be increased due to many premature, unexpected and expensive failure in system. On the other hand, if protection methods are used, it involves the cost of corrosion prevention but protection of metal is a powerful tool to reduce the overall cost and liabilities of the system. The cost also increases due to high temperature and corrosive sulphur gases, surrounding chemical and petroleum industries in industrial areas. Cost of corrosion will escalate substantially during the next decade because of worldwide shortages of construction materials, higher energy costs, aggressive corrosion environment in coal conversion processes and other factors. In fact our economy would be drastically changed if there is no corrosion and appliances would not require coatings. However, corrosion rate can be controlled and minimized. Most of the methods reported in literature are not only expensive but also toxic in nature. Therefore, a great need to investigate a non-toxic replacement that is compatible with current industrial technologies with their availability and relatively low cost, naturally substances. The easily available plant Tribulus terrestris can be used as low-cost, eco-friendly corrosion inhibitor for mild steel in aggressive industrial environment. The inhibition efficiencies of different extracts (fruit, leaf and stem) in relation to the concentration of inhibitor and temperature were determined by mass loss method. Further electrochemical measurements (EIS and potentiodynamic polarization) were also done. Surface analysis was examined by scanning electron microscope. The adsorption process obeys Langmuir adsorption isotherm. All these analysis confirm that plant Tribulus terrestris has good properties to prevent the corrosion of mild steel in acidic medium.

Investigation of Dracocephalum extract based on bulk and nanometer size as green corrosion inhibitor for mild steel in different corrosive media

“…The fact that all linear correlation coefficients ( R ) are almost equal to one shows that plant extract adsorption on mild steel surfaces follows the Langmuir adsorption isotherm. The Langmuir isotherm implies inhibitor molecule monolayer adsorption, or the inhibitor molecule occupies one active site on a metal surface 58 . Furthermore, the Langmuir adsorption isotherm revealed that organic components in plant extracts with polar atoms or groups adsorbed on the metal surface may interact via mutual attraction or repulsion 59 .…”