Evaluation of some phenothiazine derivatives as corrosion inhibitors for bronze in weakly acidic solution

摘要

Four phenothiazine derivatives have been tested as inhibitors for bronze corrosion in a solution containing Na_2SO_4 and NaHCO_3 (pH 5). Electrochemical investigations (potentiodynamic polarisation and impedance measurements) revealed that all phenothiazine derivatives exert a protective effect against bronze corrosion and, in some cases their inhibition efficiency exceeds 90% at concentration level as low as 75 μ.M. An adherent layer of organic molecules chemisorbed on bronze surface is responsible for the protective effect of the investigated compounds. Adsorption of phenothiazine derivatives on bronze obeys Langmuir isotherm. Correlation between quantum chemical calculations and inhibition efficiency of the investigated compounds was discussed using DFT method.