The Corrosion inhibition performance of hibiscus sabdariffa leaf extract on mild steel in acidic medium

Abstract

The performance of Hibiscus sabdariffa (HB) leaf extract as a corrosion inhibitor in the corrosion of mild steel in 0.5 M H₂SO₄ medium was investigated at room temperature. The experimental approaches used were gravimetric (weight loss) analysis, Potentiodynamic Polarization (PDP) technique and Fourier Transform Infra-Red Spectroscopy. The inhibitor concentrations were 5ml/L, 10ml/L, and 15ml/L for the gravimetric analysis and for the PDP, the inhibitor concentrations were 5mg/L and 15mg/L. while that of FTIR was 10ml/L. The study showed that both corrosion rate and inhibition efficiency (IE) were influenced by inhibitor concentration and exposure time. While corrosion rate increased with time of exposure, it decreased with inhibitor concentration.   The gravimetric analysis gave IE values upto 95% while the PDP approach gave IE values of 96%. The Artificial Neural Network (ANN) and Multiple Line Regression (MLR) predictive models were used to analyse experimental data. They showed that inhibitor concentration affected corrosion rate more than exposure time and ANN matched experimental data more closely than MLR.