Leveraging plant extract-impregnated LDH nanocontainer for durable corrosion protection of mild steel: Experimental and theoretical insights

Abstract

This study evaluates the potential of Daphne Gnidium Extract (DGE) loaded into a layered double hydroxide (LDH) as an efficient corrosion inhibitor for mild steel in 0.1 M NaCl. DGE-LDH hybrids, synthesized through a simple process, were characterized using X-ray diffraction, Fourier transform infrared spectroscopy , Thermogravimetry , and Zeta potential , confirming the incorporation of ∼90 mg/g of DGE into the LDH structure. Electrochemical impedance spectroscopy (EIS) revealed a peak inhibition efficiency of 90.73 % after 12 h, attributed to the controlled release of DGE and its subsequent adsorption onto the steel surface. Polarization curves supported these findings, showing a minimum current density of 3.24 μA/cm 2 and a 91 % inhibition efficiency for DGE- LDH, significantly outperforming LDHalone (70 %). Scanning electron microscopy (SEM) affirmed the formation of a protective film with homogeneously distributed DGE. Molecular dynamics simulations indicated synergistic corrosion inhibition by DGE components, as evidenced by a decreased fractional free volume (FFV) value in the presence of two of them (21.53 %). The Radial Distribution Function (RDF) approach demonstrated robust contacts between the DGE atoms and the Fe(110) surface, with bond lengths of less than 3.5 Å. Monte Carlo simulations revealed that chloride-triggered DGE release from LDH occurs via anion exchange. Furthermore, incorporating DGE-LDH into an alkyd resin coating created a “brick-wall” structure, providing a dual-defense mechanism: a physical barrier and active corrosion inhibition, which remained effective even after 40 days of immersion. These findings highlight the potential of DGE-LDH as a highly effective and durable corrosion protection coating for mild steel. • DGE-loaded MgAl LDH has been developed and characterized. • DGE-LDH's protective capabilities were electrochemically assessed. • Strong DGE-iron interaction observed in MD simulations. • MD, RDF, and FFV analysis suggest Daphnetin as a potential corrosion inhibitor for mild steel. • Alkyd/LDH loaded with DGE exhibits excellent corrosion resistance.