Abstract

Cleophas Akintoye Loto*^1,2and Roland Tolulope Loto¹

DOI : http://dx.doi.org/10.13005/ojc/350203

Potassium gluconate inhibition effects of α-brass corrosion immersed in 1 M HNO₃ were studied at room temperature (25°C). Gravimetric and potentiodynamic polarization measurement techniques were used separately for the experimental investigation. A Digi-Ivy potentiostat, connected to computer for data acquisition and analyses was used for the potentiodynamic polarization experiments. The observed potassium gluconate’s corrosion inhibition increased as the inhibitor concentration increased up to 3.5g/200ml HNO₃ where a 0.7224g weight loss was recorded in comparison with the experiment without added inhibitor which had a 3.582g weight loss at 312 hours. The corresponding corrosion rate at 3.5g/200ml HNO₃ concentration was 4.93 mm/yr while the uninhibited (control) experiment recorded a 20.33 mm/yr at 288 hrs. Corrosion inhibition efficiency values for the 1.5, 3, 3.5 and 4g/200ml HNO₃ concentrations are respectively 16.99, 41.77, 79.86 and 64.53%. Other parameters recorded include: polarization resistance, Ω (3.20E+01); corrosion rate (19.15 mm/yr) and current density, 1.01E-03 Acm^-2 for the 3.5g/200ml HNO₃ concentration in HNO₃ test medium were also achieved. A mixed type inhibitor was indicated with the recorded results of ba and bc. Adsorption isotherm showed that inhibitor protection mechanism followed both the Frumkin and the Freundlich models more than the Langmuir isotherm model.

Corrosion; Inhibition; Nitric Acid; Potassium Gluconate; Polarisation

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