Abstract

Cleophas Akintoye Loto^1,2 and Roland Tolulope Loto¹

DOI : http://dx.doi.org/10.13005/ojc/340347

The effect of combined trisaminomethane (THAM) and hexadecyltrimethyl ammonium bromide (HDTAB) as chemical inhibitors for corrosion of mild steel in 1M HNO₃ was investigated at the  ambient temperature of 25°C. The investigation was done with gravimetric (weight loss) method and also with the potentiodynamic polarisation technique. A potentiostat, Digi-Ivy potentiostat, connected to a computer for data collection and analysis was used for potentiodynamic polarisation experiment. The effective corrosion inhibition of the steel specimens in the HNO₃ test medium, using the combined inhibitors had its best performance achieved with the 6 g/ 250 mL HNO₃ concentration with weight loss of 2.99 g and a corrosion rate of 0.00913 mm/yr at 480 h of the experiment. This was closely followed with the 4 g/ 250 mL HNO₃ with 3.72 g weight loss at 480 h. At this concentration, the experiment also recorded polarisation resistance (Ω) values of 3.11E+01, corrosion rate of 1.95691E-05 mm/yr and current density of 0.000175A cm^-2 for the 6 g 250 mL. The calculated inhibition efficiency values are, respectively, 39.2 and 24.3 % for both the 6 and 4 g 250 mL^–1 HNO₃ concentrations at 480 h. The potentiodynamic polarisation results of ba and bc indicated mixed type inhibitors.

Corrosion; Electrochemical; Inhibitors; Mild Steel; Nitric Acid; Polarisation

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