Plant‐based alkaloids inhibit corrosion of marine alloys

Abstract

The term microbiologically induced corrosion (MIC) appears to be very closely related to the composition of the bio‐film which harbours the micro‐organism. Formation of an initial slimy layer on immersed metallic substrates is the rate‐controlling parameter of bio‐fouling, as uninterrupted undesirable growth of bio‐films occurs over this layer. To contain this bio‐film problem, formation of an adherent layer of toxic and inhibited corrosion product, that interacts with biofilm, could be exploited. Deals with the preliminary interactions of a few copper‐based alloys, with mildly toxic alkaloid class‐inhibitive compounds, in a simulated marine environment. It is assumed that the toxic and inhibited corrosion product and bio‐film interaction layer will interfere with the formation of the initial slimy cover on the immersed surface, responsible for bio‐fouling. It is seen that these alkaloid compounds exert a limited response on the inhibition of copper‐based alloys like monel. Brucine appears to be a more effective inhibitor for the monel surface. Pre‐oxidation of the uninhibited brass surface and also post‐oxidation of the inhibited surface appear to consolidate the corrosion product bio‐film‐inhibitor interaction layers, indicating the compatibility of these alkaloid compounds to the probable thermal strains to be encountered in engineering services. This indicates the possibility of using these compounds in heat transfer devices, like heat exchangers, where seawater is used as coolant.