Shrimp shell waste-modified natural wood and its use as a reservoir of corrosion inhibitor (L-arginine) for brass in 3% NaCl medium: Experimental and theoretical studies

Abstract

The primary objective of this study is to harness the valuable properties of natural wood waste (NWW) and a shrimp shell extract known as chitosan (Cs). In this context, and in order to prevent rapid consumption of the L-arginine inhibitor (Arg), it was encapsulated in NWW by means of a chitosan polymer. The resulting modification was verified using X-ray diffraction (XRD), which revealed the presence of chitosan and reflections corresponding to arginine in the modified wood. Additional techniques, including Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (SEM-EDS), were used for comprehensive characterization. The corrosion inhibition effect resulting from the application of NWW-Cs-Arg composite was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). The obtained results revealed that, at an optimal concentration of 2 g/L and under ambient temperature conditions (298 K), this composite demonstrated a high level of corrosion inhibition, reaching up to 75 %, exhibiting cathodic behavior. Quantum chemical calculations were also carried out to predict the active sites in the used inhibitor. The methodology employed was based on the B3LYP/6-311G++(d,p) theory in an aqueous environment. Parameters such as frontier molecular orbitals (HOMO and LUMO), global reactivity descriptors, molecular electrostatic potential (MEP), and Mulliken population have been studied to assess local reactivity and identify reactive centers and potential nucleophilic and electrophilic attack sites. Weak interactions were analyzed using topological approaches (ELF, LOL, and NCI). It is noteworthy that the arginine molecule interacts through hydrogen bonds between its guanidine group and the hydroxyl groups present in the wood and chitosan residues. Meanwhile, the amine groups of chitosan promote charge transfer between arginine and copper atoms, particularly through the NH groups in the alpha position relative to the C = O group.