Corrosion Inhibitory Properties of Some Condensation Products on Oil Well Tubular Steel (N - 80) and Mild Steel in Acidic Environment

摘要

Selected condensation products of aromatic aldehydes and thiosemicarbazide have been synthesized and evaluated as corrosion inhibitors for mild steel and oil well steel (N - 80) in 15 percent HCl at 105 +- 2 deg C by weight loss method. All the condensation products showed excellent performance. 1-Cinnamaldehyde thiosemicarbazone (CTS) was found to be the best corrosion inhibitor. It exhibited 99.67 percent inhibition efficiency for mild steel and 97.26 percent for N - 80 steel at 5000 ppm of inhibitor concentration. The potentiodynamic polarization studies carried out at room temperature on mild steel in 15 percent HCl containing 500 ppm of condensation products and N - 80 steel in 15 percent HCl containing 500 ppm of CTS showed that all the investigated compounds except 1-Dimethylaminobenzaldehyde thiosemicarbazone (DTS) are mixed type inhibitors. DTS exhibited predominantly cathodic behaviour. The adsorption of all the condensation products was found to obey Temkin's adsorption isotherm.