Corrosion behaviour of mild steel in weak acidic solutions containing nitrite ions and Vaccinium Myrtillus

ABSTRACTClosed water circuit systems are mostly used to transfer heat in many industrial and commercial applications. Corrosion causes serious to damages to installation and blockage in the pipes by corrosion products prevent coolant flow thus influence heat transfer efficiency. Use of inhibitors are one of the most important methods to prevent closed systems from corrosion. Inorganic compounds such as chromates, molybdates and nitrites have been widely studied to prevent metals in closed circuit from corrosion. These inhibitors are not only expensive but also harmful to the environment. Recently researches are focused on green inhibitors as they are biodegradable, do not contain heavy metals or other toxic compounds. Plant products are the main sources of environment-friendly green inhibitors such as amines, tannins.The aim of the present work is to study the effect of a naturally occurring, economical and environmentally safe product Vaccinium myrtillus (VM) as a corrosion inhibitor that could be used in combination with nitrite based inorganic inhibitors, thus reducing the amount of inorganic inhibitor and making it more tolerable to the environment. In the present study the individual effect of nitrite ions, Vaccinium Myrtillus plant extracts and their mixture on corrosion behaviour of mild steel were investigated by Tafel extrapolation method. Synergistic effect of different inhibitor blends was evaluated. Kinetic and thermodynamic parameters specifying characteristics of a corrosion system in the presence and absence of inhibition were evaluated. Different adsorption isotherms were tested for describing the adsorption behaviour of TP and VM combination on mild steel surface.Keywords: Corrosion inhibitors, Vaccinium myrtillus, Tafel extrapolation, synergistic effect