Inhibition of Brass Corrosion in 3% NaCl Solution by Sodium Diethyldithiocarbamate

Inhibition of brass corrosion by sodium diethyldithiocarbamate (DDTC) in 3% sodium chloride (NaCl) solution was investigated using the mass-loss method, electrochemical impedance spectroscopy (EIS), polarization curve method, and surface analysis method. Mass-loss results showed that the DDTC was an excellent inhibitor for brass in 3% NaCl solution with an inhibition efficiency of 95% and a corrosion rate of 0.105 mm/y at a concentration of 120 mg/L after 5 days' immersion. EIS results indicated that the polarization resistance (R(p)) values of brass electrodes initially increased with the DDTC concentration and immersion time, reaching a maximum at 120 mg/L and 72 h. After that, the R(p) values decreased with a further increase in DDTC concentration and immersion time. Results from the polarization curve revealed that the inhibitor had simultaneous inhibitory effects on anodic and cathodic behaviors of brass. The corrosion inhibition mechanism of DDTC on brass inferred from infrared spectra and EDS was attributed to the formation of an adsorbed film on the brass surface, which protects brass against chloride ion corrosion.