GREEN HIGH-EFFICIENCY CORROSION INHIBITOR

A corrosion inhibitor for use in aqueous fluids, e.g. brine, which contact a metal surface, contains a blend or cross-linked reaction product of a main chain type polybenzoxazine (MCTPB) and a chitosan component selected from the group consisting of chitosan, chitosan glycol, and combinations thereof. The MCTPB can be made by reacting formaldehyde, bisphenol A, and tetraethylenepentamine (TEPA). The corrosion inhibitor may contain a small amount of an inorganic acid and/or an organic acid. Suitable organic acids include, but are not necessarily limited to organic acid selected from the group of carboxylic acid consisting of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, citric acid, oxalic acid, malic acid, lactic acid, benzoic acid, or selected from the group of sulfonic acids consisting of p-toluenesulfonic acid, trifluoromethanesulfonic acid, 2-aminoethanesulfonic acid, alkyl-aryl-sulfonic acids such as dodecylbenzenesulfonate, polymeric sulfonic acids, fluorinated derivatives of these organic acids, and combinations thereof.