Investigating the efficacy of Curcuma longa against Desulfovibrio desulfuricans influenced corrosion in low-carbon steel

Abstract

Abstract The effectiveness of Curcuma longa extract in the control of low-carbon steel corrosion caused by sulfate-reducing bacteria (SRB) in Baar’s medium was investigated. The SRB taken for the study was Desulfovibrio desulfuricans. Specimens in contact with the medium containing SRB exhibited a corrosion rate more than 10 times that of the specimens in contact with the medium without SRB. The weight loss studies showed that the addition of 50 ppm C. longa extracts to the medium containing SRB resulted in an average inhibition efficiency of 91.2% for a four week immersion period. The inhibitor extract altered the reaction rates of both cathodic and anodic reactions which were confirmed from the potentiodynamic polarization (PP) studies. Electrochemical impedance spectroscopy (EIS) studies showed a reduction in the number of sessile bacteria upon inhibitor addition which was confirmed by the microscopy. Severe pitting was observed in the morphological analysis of the specimen in the absence of inhibitor treatment. Apart from adsorption onto the specimen surface to minimize the biocorrosion, the inhibitor extract also served as an anti-film forming and antibacterial agent.