Studying the adsorption/inhibition impact of the cellulose and lignin compounds extracted from agricultural waste on the mild steel corrosion in HCl solution

Although the pistachio nut is a popular agricultural product for different applications, its hard shell can be considered as a fruitless waste. For the first time, the extract of the hard shell of pistachio nut, which contains some essential bio-active/eco-friendly compounds like cellulose and lignin, was employed as organic eco-friendly inhibitors for steel corrosion mitigation in acidic solution. In this regard, different concentrations of the extract were mixed to 1 M HCl solution, and its inhibition efficiency, as well as the mechanisms of the inhibition, was evaluated via EIS and polarization methods. Besides, the surface morphology, roughness, and chemistry of the immersed steel in the acidic solution protected with the green inhibitor were investigated by FE-SEM, atomic force microscopy, and contact angle analyses, respectively. The computer modeling at the electronic level by DFT and molecular-scale by molecular dynamic simulation was applied for investigating the interaction between the inhibitors molecules and metal surface in the acidic solution. 92% inhibition efficiency was obtained by the EIS test in the case of using 800 ppm of the green inhibitor in the acid solution after 6 h. Also, the polarization test results demonstrated that the inhibitor acted its role via a mixed-type mechanism. Furthermore, the adsorption of the extracted compounds on the surface of the immersed samples obeyed the Langmuir isotherm, and the adsorption was in both chemical and physical processes (Delta G degrees(ads) = -21.31 kJ/mol). (C) 2020 Elsevier B.V. All rights reserved.