Influence of Polythiophene-Anthraquinone sulphonic acid (PTh-AQSA) nanopowder on corrosion inhibition of mild steel in HCl solution

A new and effective polymeric corrosion inhibitor, Polythiophene-Anthraquinone sulphonic acid PTh-AQSA has been prepared and characterized by UV-Visible and FTIR spectroscopy studies. Its influence on corrosion inhibition of mild steel in 1N HCl solution was studied using chemical and electrochemical techniques. It was found that the inhibition efficiency increased with the increase of PTh-AQSA upto 700ppm and beyond this concentration, its inhibition efficiency was decreased from 95.2 to 93.1%. It indicates that 700ppm is the optimum concentration to get maximum corrosion protection for mild steel 1N HCl solution. The results obtained from chemical and electrochemical measurements are in reasonably good agreement. The potentiodynamic polarization studies revealed that PTh-AQSA act as mixed type inhibitor. Adsorption of PTh-AQSA on mild steel surface follows Langmuir adsorption isotherm. The surface characteristics of the inhibited and uninhibited mild steel were investigated by scanning electron microscope studies.