USE OF NATURAL PLANTS AS GREEN CORROSION INHIBITORS AN OVERVIEW

Corrosion is the destructive phenomenon which affects almost all metals. Iron is the most widely used metal and one of the first for which corrosion was encountered. Corrosion can cause disastrous damage to metal and alloy structures causing economic consequences in terms of repair, replacement, product losses, safety and environmental pollution. Among the various methods to avoid or prevent destruction or degradation of metal surface, the corrosion inhibitor is one of the best know methods of corrosion protection and one of the most useful on the industry. The presence of N, S and O in organic corrosion inhibitors reported excellent inhibition efficiency. But, unfortunately they have the undesired toxic effect on environment. The environmental toxicity of organic corrosion inhibitors has prompted the search for green corrosion inhibitors. Green inhibitors are biodegradable, environmentally friendly and ecologically acceptable; do not contain heavy metals or other toxic compounds. Green inhibitors extracted from plants and plant products are inexpensive, readily available and renewable. Also, plants and natural product extracts have been posed to achieve the target of employing as a cheap, environmentally acceptable, abundant source, readily available and effective molecules having very high inhibition efficiency and low or zero environmental impact. As green inhibitors we have used oleuropine extracted by olive leaves, piperine extracted by black pepper, quercetin extracted by red onion. The corrosion inhibition efficiency was investigated using potentiodynamic polarization measurements. Corrosion inhibition efficiency of these green inhibitors was tested for iron B500, in acidic media.