Durational and Thermal Behaviour of Sodium carboxymethyl Cellulose and its Mixtures with Potassium Iodide and Polyethylene Glycol in Mitigating Acid Corrosion of Aluminum

Abstract

Durational and thermal behaviour of sodium carboxymethyl cellulose (SCMC) and its mixtures with potassium iodide (KI) and polyethylene glycol (PEG) respectively on aluminum exposed to 1.5 mol/L HCl solution at 30‒60 ℃ for 24‒120 h was studied by mass loss measurements, potentiodynamic polarization technique and scanning electron microscopy. Mass loss measurements show that aluminum corroded in 1.5 mol/L HCl solution for 24‒120 h at 30‒60 ℃. However, the corrosion was appreciably inhibited by adsorption within 2000 mg/L SCMC with an inhibition efficiency (IE) of 68.09%. The IE was increased to 76.60% and 89.36% within 2000 mg/L SCMC+KI and 2000 mg/L SCMC+PEG respectively due to synergistic effect. However, inhibition efficiency of the compounds was retarded with the increase in immersion time and temperature. Calculated values of energy of activation (E_a) and heat of adsorption (Q_ads) further consolidated the adsorption was physical as proposed in Freundlich isotherm model. All the compounds demonstrated mixed-type behaviour with a remarkable anodic effect. Scanning electron microscopy provided visual evidence of corrosion inhibition phenomenon by the compounds. The inhibitory effectiveness of the compounds anchored on immersion time, temperature, concentration and probable synergistic effect in convenient mixed compound solutions.