Benzimidazole: Small planar molecule with diverse anti-corrosion potentials

The cost of corrosion greatly impacts the economics of industrialized nations that a significant percentage could be equated in some way to a fraction of their GDP. The use of organic inhibitor compounds has proven to be one of the most practically effective methods for mitigating metal corrosion in various aggressive media. Most inhibitors play important roles in retarding corrosion due to the presence of sites of adsorption for metal surface bonding. Benzimidazoles being a unique stock of bicyclic compounds with a fused benzene/imidazole structure belong to this class of inhibitors. With their numerous therapeutic properties, their biological activities are also accompanied by safe and efficient corrosion protection abilities with negligible negative effects on man and his environment. Their superior inhibiting potency for metal corrosion over some other compounds is attributed to their rate of molecular adsorption at the metal/solution interface due to the presence of the nitrogen atom bearing the sp² electron pair known to act as metal surface anchoring sites. This review covers older and most recent investigations related to the application of a number of benzimidazole derivatives as corrosion inhibitors for industrial metals in many simulated and real aqueous media. The mechanisms of corrosion protection for each inhibition system have also been highlighted via experimental and theoretical based approaches in acid, alkaline and near neutral media. The use of this class of compounds for microbial corrosion inhibition and sweet corrosion have also been proposed for future studies since reported research in this aspect are relatively scanty.