OLEUROPEIN EXTRACTED FROM OLIVE LEAVES, AN EFFICIENT INHIBITOR AGAINST THE CORROSION OF METALS AND ALLOYS

Corrosion is a naturally occurring phenomenon commonly defined as deterioration of metal surfaces caused by the reaction with the surrounding environmental conditions. Corrosion can cause disastrous damage to metal and alloy structures causing economic consequences in many aspects of the life. There are several ways to prevent corrosion. The use of inhibitors for the control of corrosion of metals and alloys which are in contact with aggressive environment is one among the acceptable practices used to reduce or prevent corrosion. Though many synthetic compounds showed good anticorrosive activity, most of them are highly toxic to both, human beings and environmental. It is very important to choose cheap and safety handled compounds to be used as corrosion inhibitors. The aqueous extract of olive leaves represent a great inhibitive action against the corrosion of carbon steel in acidic media. The principal active component in olive leaf extract is oleuropein, a natural product of the secoiridoid group. Oleuropein is a heterosidic ester of elenolic deteracid and 3,4-dihydroxyphenylethanol, containing a molecule of glucose, the hydrolysis of which yields elenolic acid glucoside and hydroxytyrosol. Oleuropein from the olive leaves was obtained by aqueous extraction in temperature 60oC acidified with HCl 0.1M (pH=3), for four hours. The solution was stored at 4oC and in the dark. The product of extraction was analyzed with infrared (IR) spectroscopy, in order to define it’s chemical structure. Also we defined the yield, density, pH and melting point of the product. The product of extraction result to be oleuropein and we propose to use it as corrosion inhibitor.