Potassium Gluconate inhibition of α-Brass Corrosion in 1 M HNO3

Potassium gluconate inhibition effects of alpha-brass corrosion immersed in 1 M HNO3 were studied at room temperature (25 degrees C). Gravimetric and potentiodynamic polarization measurement techniques were used separately for the experimental investigation. A Digi-lvy 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 3.59/200 ml HNO3 where a 07224 g weight loss was recorded in comparison with the experiment without added inhibitor which had a 3.582 g weight loss at 312 hours. The corresponding corrosion rate at 3.5g/200 ml HNO3 concentration was 4.93 mm/yr while the uninhibited (control) experiment recorded a 20.33 mm/yr at 288 hours. Corrosion inhibition efficiency values for the 1.5, 3, 3.5 and 4g/200m1 HNO3 concentrations are respectively 16.99, 41.77, 79.86 and 64.53%. Other parameters recorded include: polarization resistance, Omega (3.20E+01); corrosion rate (19.15 mm/yr) and current density, 1.01E-03 Acm(-2) for the 3.5g/200 ml 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.