Corrosion inhibition, adsorption and thermodynamic properties of poly(vinyl alcohol-cysteine) in molar HCl

Abstract

Chemical synthesis of water soluble conducting polymer composite poly(vinyl alcohol-cysteine) [PVAC] was carried out in oxalic acid medium using ammonium persulfate. The composite was characterized by UV, FTIR and SEM–EDX. The corrosion inhibition performance of PVAC on mild steel in molar hydrochloric acid solution was studied by weight loss and electrochemical methods. A maximum inhibition efficiency of 94% was observed in the presence of 0.6 wt% of the inhibitor. The influence of inhibitor concentration, solution temperature, and immersion time on the corrosion of mild steel has been investigated. Polarization measurements showed the mixed type inhibitive nature of the polymer composite. The results obtained from the different methods are in good agreement. The various kinetic and thermodynamic parameters of metal dissolution and composite adsorption processes were evaluated from the weight loss methods in order to elaborate the adsorption mechanism. Adsorption of inhibitor obeyed El-Awady adsorption isotherm.

Keywords

• Mild steel
• Poly(vinyl alcohol-cysteine)
• Weight loss
• Polarization
• Impedance spectroscopy
• El-Awady isotherm