CORROSION INHIBITION OF MILD-STEEL IN AQUEOUS-SOLUTION CONTAINING H2SBY SOME NATURALLY-OCCURRING SUBSTANCES

The corrosion inhibition of mild steel by some naturally occuring subs tance was evaluated in absence and presence of 600 and 1200 mg H2S/l i n 3% NaCl aqueous solution and pH of 3 and temperature of 25 degrees C . These naturally occurring substance included the water extracts, cou marines and fatty matters extracts of some Egyptian plants. These plan ts included: 1) Nigella Sativa (Family Ranunculacease) (Extract 1), 2) Coriandrum Sativum (Family Umbelliferea) (Extract II), 3) Ricinus com munis (Family Euphorbiaceae) (Extract III). The galvanostatic anodic a nd cathodic polarization measurements were used for studying the corro sion behavior of mild steel and evaluation of the percentage inhibitio n of the undertesting extracts of these three plants and also preparat ion of fatty matters and coumarin fractions were mentioned.