Evaluation of Glebionis coronaria L. flower extract as a novel green inhibitor for mild steel corrosion in acidic environment

The goal of this study is to evaluate the behaviour of Glebionis coronaria L. flower extract as a green corrosion inhibitor for mild steel corrosion in 1 M HCl solution.The corrosion inhibition of the ethanolic extract of Glebionis coronaria L. flower was studied by weight loss, electrochemical impedance spectroscopy measurements, and potentiodynamic polarisation. The inhibition efficiency was improved with increasing extract concentration. The maximum inhibition percentage (> 95%) was achieved at 400 ppm. The high efficiency of this extract is due to the presence of hetero atoms and π-electrons in its constituents as proved by the results of Fourier transform infrared analysis (FTIR). The temperature rise leads to reduction in the inhibition efficiency of this flower extract. The calculated activation parameters (E_a, ΔH^*, ΔS^*) confirms the inhibition behaviour of this extract. The Langmuir isotherm model fits the results well. This extract serves as a mixed-type inhibitor, according to the kinetic parameters computed from PDP results. Moreover, the corrosion current density decreased from 2.19 ± 0.18 mA cm⁻² for the blank solution to 0.07 ± 0.01 mA cm⁻² for the corrosive electrolyte containing 400 ppm of the investigated flower extract. In addition to FTIR spectroscopy, the results of surface analysis using a scanning electron microscope (SEM) further supported the extract’s ability to inhibit mild steel corrosion in an acidic solution through physisorption and chemisorption mechanisms.