Corrosion protection of mild steel in acidic medium by titanium-based nanocomposite of Chromolaena odorata leaf extract

Abstract

The quest for efficient, thermally stable, alternative and eco-friendly anticorrosion additives for industrial cleaning and pickling operations necessitated this study. From methanolic extract of Chromolaena odorata leaves, titanium nanocomposite was synthesised, characterised and applied as a corrosion inhibitor of mild steel in acidic medium. The Titanium-Chromolaena odorata (Ti–CO) nanocomposite was characterised using Fourier-Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX), High-Resolution Transmission Electron Microscopy (HRTEM) and N2 adsorption/desorption measurement. The FTIR result identified O–H, CO, CC and SO functional groups in the nanocomposite while XRD patterns of calcined Ti–CO nanocomposite was found to correspond to the anatase phase of TiO2 with average crystallite size of 10.22 nm. Similarly, Ti–CO is a mesoporous material with BET (Brunauer-Emmett-Teller) surface area of 172.82 m2 g−1. As revealed by HRTEM, the particle size of the Ti–CO ranged from 1.45 to 2.17 nm. The inhibition performance of Ti–CO on the corrosion of mild steel in 1.0 M HCl was evaluated by electrochemical and weight-loss techniques. Weight-loss measurements showed that Ti–CO had higher inhibition efficiency (92.39%) than methanolic C. odorata extract (84.77%) at 1.0 g/L of the inhibitor. The efficiency increased as the inhibitor concentration increased but reduced with an increase in temperature. Data from electrochemical study revealed that Ti–CO was adsorbed on the metal surface and this phenomenon increased the resistivity of Ti–CO towards charge transfer of the solution. Thermodynamic results showed that the dissolution of mild steel in the absence and presence of Ti–CO is endothermic and orderly. Langmuir adsorption model predicted physical adsorption mode of the inhibitor on mild steel surface and surface morphology study using SEM-EDX confirmed the formation of a protective layer on the surface of the mild steel. The Ti–CO nanocomposite produced can be effectively utilised as an alternative corrosion inhibitor of mild steel in acidic media.