Protection of Aluminium in Acidic Environment and Inhibition Efficiency of Aminophenol-N-Benzylidene - Theoretical and Practical Investigation

Abstract

Aluminium has a remarkable industrial importance. Aluminium and its alloys are exposed to the action of acid in industrial processes where acid play an important role such as oil well acidizing, acid pickling, acid cleaning and descaling. This can lead to substantial metal loss due to corrosion. The use of inhibitors is one of the most practical options to protect metal from corrosion. Organic and inorganic compounds are usually added to HCl as corrosion inhibitors. The present work is carried out to find the effective inhibitor with minimum concentration but maximum inhibition. The corrosion inhibition effect of o,m,p-Aminophenol-N-Benzylidene (o,m,p-AmphNB) for pure Aluminium in 1M HCl were investigated by means of weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Electrochemical studies were carried out using standard three electrode cell where Calomel electrode act as a reference electrode, Platinum electrode as counter electrode and Aluminium electrode as working electrode. The values of o ads G  indicates the competitive Chemisorption and physisorption, Potentiodynamic polarization parameters revealed the mixed mode of inhibition with predominance of cathodic inhibition. The EIS showed linear correlation with concentration of inhibitor & Rctl while Cdl inversely correlated. Quantum chemical calculations based on density functional theory (DFT) method were performed on studied inhibitors to ascertain relationship between molecular structure and their inhibition efficiency. Correlation analyses between experimental and theoretical values were performed to conclude that the inhibition effect of inhibitors could be explained in terms of electronic properties.