Abstract

KHATBI, Salma; GOUALE, Youssef; LAMIRI, Abdeslam  and  ESSAHLI, Mohamed. Improving the Corrosion Resistance of Lead in H2SO4 4 M by the Addition of Phosphoric and Phosphonic Compounds for Lead Grid Batteries. Port. Electrochim. Acta [online]. 2016, vol.34, n.6, pp.383-393. ISSN 0872-1904.  https://doi.org/10.4152/pea.201606383.

The effect of the addition of phosphoric acid ((HO)3P=O), potassium hydrogen phosphate ((HO)2P(O)(O-K+)), dimethyl vinylphosphonate (CH2=CH-P(O)(OCH3)2) and vinylphosphonic acid (CH2=CHP(O)(OH)2) on lead corrosion in 4 M H2SO4 was studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results show that phosphoric acid and potassium hydrogen phosphate, added to an optimal concentration of 0.4 M, reduce the lead passivation current and increase its corrosion current, with charge transfer as the main reaction mechanism at the interface metal/electrolyte. They also increase PbO2 formation's potential when they are added at larger concentrations, while adding dimethyl vinylphosphonate and vinylphosphonic acid up to 0.3 M reduces corrosion current and lead passivation current. This last product appears to suppress the formation of PbO2. The parameters of potentiodynamic polarization are in good agreement with those of EIS.

Keywords : corrosion; inhibition; lead; phosphoric acid; potassium hydrogen phosphate; dimethyl vinylphosphonate; vinylphosphonic acid.

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