Abstract
A study was conducted the effects and mechanisms of three chelating reagents, 8-hydroxyquinolin [HQ], 8-mercaptoquinolin [MQ] and anthranilic acid [AA], in inhibiting zinc corrosion in 3%NaCl solution (25°C, pH=5.0, 7.0 and 9.0). The chelating reagents were expected to protect the zinc surface by polarization and weight loss, while inhibiting mechanisms were investigated by analysis of infrared spectra and infrared-attenuated total reflection spectra.
Experiments on polarization and weight loss showed that HQ and MQ had good inhibiting effects at all values of pH studied, but AA had a high inhibiting effect only at pH=5.0. Analysis of the infrared spectra and infrared-attenuated total reflection spectra showed that HQ and MQ formed insoluble metal chelate complexes on the zinc surface at all values of pH studied, but in case of AA, no complexes were formed at 7.0 and 9.0. Reagents, HQ and MQ, which formed metal chelate complexes with zinc, acted as effective inhibitor at all values of pH studied, but AA form no complexes at pH 7.0 and 9.0 showing poor inhibiting effect.
