Inhibition of acid corrosion of mild steel by Telfaria occidentalis extract

Purpose - To investigate the efficacy of Telfaria occidentalis extract as a corrosion inhibitor for mild steel in 2 M HCl and 1 M H2SO4 solutions, respectively, and to assess the effect of temperature and halide additives on the inhibition efficiency. Design/methodology/approach - Corrosion rate was monitored by careful volumetric measurement of the evolved hydrogen gas at fixed time intervals. Inhibition efficiency was determined by comparing the corrosion rates in the absence and presence of additive. Attempts were made to elucidate the inhibition mechanism from the trend of inhibition efficiency with temperature. The adsorption mode of inhibiting species in the extract was assessed by considering the influence of both acid and halide ions on inhibition efficiency. Findings - Telfaria occidentalis extract inhibited mild steel corrosion in 2 M HCl and 1 M H2SO4 solutions. Inhibition efficiency increased with extract concentration but decreased with rise in temperature. Synergistic effects increased the efficiency of the extract in the presence of halide additives in the order KCl < KBr < Kl. Protonated species in the extract composition played a vital role in the inhibiting action. Originality/value - This paper provides new information on the inhibiting characteristics of Telfaria occidentalis extract under the specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodising and surface coatings.