Corn Silk as Corrosion Inhibitor for Mild Steel in 0.1M HCl Medium

Abstract

The effectiveness of corn silk water extract (CSWE) as corrosion inhibitor of mild steel in 0.5M HCl solution at 303K,313K and 323K was investigated in this work. Various concentrations of CSWE (5%v/v, 10%v/v, and 15% and 20% v/v) were prepared from dried corn silk. The study was carried out using weight loss and AAS analysis. The results of the AAS analysis collaborated weight loss measurements on the efficiency of CSWE as corrosion inhibitor. Inhibition efficiency of 77.7% and 72.0% was obtained respectively using both methods. Inhibition efficiency increased with increase in concentration of CSWE (5%v/v<10%v/v <15% < 20% v/v) while corrosion rate decreased as concentration increased. Increase in temperature reduced inhibition efficiency and CSWE was shown to be most effective at 303K than at 313K and 323K. Kinetic study of the process proposed a first order reaction type. From thermodynamic parameters, inhibition was attributed to the existence of a protective film on metal surface by interaction between inhibitor molecules and metal ions in solution..Reaction rate constant values calculated were 0.0234, 0.0818 and 0.104 for the blank solution and 0.0049, 0.0328, 0.0416 for the highest inhibitor concentration of 20% v/v respectively at the different temperatures studied.Data obtained were subjected to Langmuir, Temkin and Frendlich isotherms. Langmuir model was found to be most fitted of the three models. The utility of a waste material as corrosion inhibitor is once more reported.