Investigation of substituted thiazolidinediones as corrosion inhibitors on different metals in acidic media

Abstract

This study is based on the synthesis of four Thiazolidinediones (TZD) derivatives which are Ethyl 2-(5-(4-methoxybenzylidene)-2,4-dioxothiazolidin-3-yl)acetate (EMDA), Ethyl 2-(5-(Benzo[d][1.3]dioxol-5ylmethylene)-2,4dioxothiazolidin-3-yl)acetate (EBMDA), Ethyl 2-(5-(substituted benzylidene)-2,4-dioxothiazolidin-3-yl) acetates (EBDA) and Ethyl 2-(2-(5-(Benzo[d][1.3]dioxol-5-ylmethylene)-2,4-dioxothiazolidin-3-yl)acetamido)glycinate (EBDMDG) as corrosion inhibitors for two different metals (zinc and aluminium) in 1.5M hydrochloric acid solution at various temperatures. The corrosion inhibition characteristics including corrosion inhibition efficiencies and inhibitor-metal adsorption/desorption behaviour were studied using electrochemical impedance spectroscopy, potentiodynamic polarization, and gravimetric analysis. The results obtained from the gravimetric analysis indicate that the corrosion inhibition efficiency of zinc and aluminium metal in an acidic environment increased with an increase in the concentration of the inhibitors. The inhibition efficiency of EBMDA, EBDA, and EBDMDG inhibitors for zinc metal is directly proportional to temperature whereas inhibition efficiency for aluminium metal is inversely proportional. The inhibition efficiency of EMDA inhibitor for zinc is inversely proportional to temperature and directly proportional to temperature for aluminium metal. Both inhibitors obeyed Langmuir adsorption. Electrochemical studies have been carried out using PDP and EIS. PDP was used to obtain corrosion parameters while EIS was applied to determine the charge transfer during corrosion. The result indicates that all four compounds are mixed type inhibitors also when the concentration of inhibitor increase the charge transfer resistance during corrosion increased.