Corrosion protection of Daphne Gnidium leaf extract encapsulated with beidellite clay: An effective pigment for a long-lasting and eco-friendly coating formulation

Abstract

The development of eco-efficient and environmentally friendly active anticorrosion coatings for metal substrates represents a fundamental step in many engineering applications. In this work, a novel corrosion inhibitor was elaborated beidellite clay (Na-BDT) and an aqueous extract of Daphne Gnidium (DGE). The modification of the clay by DGE was monitored and characterized using cyclic voltammetry (CV), X-ray diffraction (XRD), UV/visible spectroscopy (UV/Vis), and Fourier transform infrared spectroscopy (FT-IR) techniques. The results showed that the clay modification was successfully achieved, with a DGE adsorbed amount of approximately 99 mg/g. Mild steel is effectively protected against corrosion in 0.1 M NaCl solution thanks to the progressive release of DGE, resulting in the lowest corrosion current density (7.22 µA/cm2) and the highest charge transfer resistance (7.20 kΩ.cm2) after 48 h of immersion. The calculated inhibition efficiency reaches a maximum of approximately 83 %. DGE-modified clay (DGE-BDT) was then dispersed into an alkyd resin (5 wt%) to enhance the corrosion protection of mild steel. The anti-corrosion performance was maintained over a long period of time and remains higher than that of the coating containing a commercial triphosphate aluminum (TPA) corrosion inhibitor.This study demonstrates the potential of encapsulating natural extracts as an eco-friendly corrosion inhibitor with high performance capabilities.