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Received: August 27, 2018; Revised: October 05, 2018; Accepted: October 05, 2018
Abstract: The effects of birch sap, a possible natural corrosion inhibitor, on the corrosion behavior of steel in chloride solution were investigated. The corrosion rate was significantly reduced by the addition of 1~5 mL of birch sap to 500 mL of 3wt% NaCl or 3wt% CaCl2 solution. A remarkable increase in the pitting potential in NaCl solution was observed by the addition of birch sap although it was almost constant in CaCl2 solution. The corrosion rate of steel in both NaCl and CaCl2 birch sap solution without addition of water was higher compared to that of aqueous solution without birch sap as the pH of the birch sap was 4.0. The presence of organic compounds like, fructose, galactose, glucose, and palmitic acid in the birch sap are thought to be adsorbed effectively on the metal surface, which provided corrosion protection. However, the inorganic elements including Na, Ca, K, Mg, Mn, S, etc. present in the birch sap exhibited no role in corrosion inhibition.