Dodecylamine encapsulation in layered smectite clay mineral: Release and application for copper corrosion inhibition in 0.1 M nitric acid solution

Abstract

The economic and environmental impact associated to the use of corrosion inhibitors for metal protection directs research works towards systems based on the encapsulation of these active principles for a more sustainable approach. Here, dodecylamine (DA) was intercalated in the interlayer space of a smectite and the intercalated amine once released, was used as copper corrosion inhibitor in 0.1 M nitric acid solution. The effective synthesis of the organoclay was confirmed by X-ray diffraction, infrared spectroscopy and thermogravimetric analysis. The inhibition percentages obtained by electrochemical methods increased with the release time (from 55% after 0.5 h to 90% after 24 h). This result indicates a slow release of intercalated amine present in the organoclay. Gravimetric monitoring of corrosion experiments performed continuously for 28 days confirm the decrease of copper corrosion rate with release time. Based on thermodynamic studies and surface analysis by scanning electron microscopy, the released amine was physiosorbed on copper surface, leading to the formation of a film that protect the metal against nitrates and dissolved oxygen, responsible of the cathodic reactions that initiates copper corrosion.