Lycium barbarum extract as an environmentally friendly corrosion inhibitor for AISI 52100 bearing steel in hydrochloric acid medium

This study reports the use of Lycium barbarum extract (LBE), a green and environmentally friendly additive, to inhibit the corrosion of AISI 52100 bearing steel in 1 M hydrochloric acid (HCl) solutions. Corrosion inhibition was experimentally investigated via the weight loss method and electrochemical analyses. The surface morphologies were evaluated by scanning electron microscopy (SEM), and the chemical compositions were analyzed via energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). The experimental electrochemical and weight loss results demonstrated that LBE has excellent inhibitory properties, with the highest inhibition efficiencies of 92.68% and 92.31 % when the concentration is 500 ppm, for steel immersed in HCl solutions. Surface coverage studies revealed that the data for the adsorption of LBE on steel were consistent with the Langmuir isotherm. The initial process was investigated via polarization analysis, and the LBE adsorption process was found to be a hybrid of physical and chemical adsorption. To investigate the effectiveness of LBE in preventing corrosion, the corrosion inhibition mechanism was analyzed via a wettability study, high performance liquid chromatography (HPLC) measurements and theoretical quantum chemical calculations. The results indicated that Ara, Rha, Man and Glu played significant effect on the protection of bearing steel in 1 M HCl solution.