PEMANFAATAN EKSTRAK KULIT BUAH MARKISA SEBAGAI INHIBITOR KOROSI BAJA LUNAK (MILD STEEL) DALAM LARUTAN ASAM

Abstract

The role and important of plant extract and oil have been improving significantly as they are widely used as corrosion
inhibitor. Corrosion inhibitor from natural plant hase been proven very effective in decreesing corrosion rate with high
efficiency. In this study, inhibiting action of markisa shell extract as a natural product for inhibiting corrosion of mild
steel in acid electrolyte has been studied using weight loss method. Markisa fruit shell was extracted to acid solution and
then evaporated to produce solid extract and it was then used as inhibitor corrosion in acid electrolyte. Mild steel
specimen was immersed at themperature 30 - 70oC with inhibitor concentration from 0 to 1000ppm for 3 days.
Corrosion rate, inhibition efficiency and activation energy were then calculated. Markisa fruit shell extract which
contain lignin can be used as corrosion inhibitor of mild steel in acid electrolyte. The increase of immersion
themperature causes increase in corrosion rate of mild steel with or without inhibitor. This possibly caused by
degradation of thin layer of inhibitor at higher themperature. The optimum inhibitor efficiency of 85% obtained at
inhibitor concentration 200ppm, whereas the activation energy of corrosion reaction at themperature 30oC to 70oC with
inhibitor concentration 0 and 200ppm where found 26.40 and 58.03 kJ/mol. This increase in activation energy suggests
that corrosion inhibitor actually functioning as it is ecpected to decrease the rate of corrosionsignificantly.