Assessment of corrosion inhibition performance of olive leaf extract mediated chitosan–Ag nanocomposites and influence of KI addition for X60 steel in acid solution

Abstract

Chitosan–silver (CHT–Ag) nanocomposite (NCP) containing various dosages of chitosan (0.5, 1.0 and 2.0 g) was synthesized in-situ using olive leaf extract (OLE) as reducing and capping agent. The OLE mediated CHT–Ag NCP was characterized using UV–vis spectrometer, attenuated total reflectance-infrared spectroscopy (ATR-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) techniques. The prepared NCP was assessed as corrosion inhibitor for X60 steel in 5% HCl solution using weight loss (WL) and electrochemical (electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization (PDP)) methods complemented by surface analysis of the corroded carbon steel (CS) without and with the NCPs utilizing scanning electron microscopy (SEM)/EDS, 3D optical profilometer and atomic force microscopy (AFM). The influence of adding KI on the corrosion inhibition performance of NCPs was investigated as well. TEM results indicate that CHT–Ag nanocomposites are polydisperse and spherical in shape with sizes in the range of 3.7–18.1 nm. The crystalline nature of Ag nanoparticles in the nanocomposites was confirmed by XRD and TEM examination. The prepared NCPs function as effective inhibitors for X60 CS corrosion in the acidic environment. Corrosion inhibition effect was observed to increase with rise in the NCPs concentration with the optimum inhibition efficiency (IE) obtained at the maximum dosage of 0.5% studied. The order of corrosion inhibition performance followed the trend CHT2.0 – Ag > CHT1.0 – Ag > CHT0.5 – Ag NCP. Also, IE was found to decrease with rise in temperature. The PDP data indicates that the NCPs alone and in combination with KI, reduced X60 CS corrosion via the mechanism of active site blocking effect. The addition of KI to the NCPs improves IE but not due to synergism. The surface assessment data confirms the establishment of a protective layer due to NCPs adsorption on the X60 CS surface.