Study on the inhibition effect of Carboxymethyl Cellulose on aluminum corrosion in sulfuric acid solution

The corrosion accompanied with hydrogen gas evolution process is the main obstacle preventing the widespread use of aluminum in the industry. The use of corrosion inhibitors is one of the most effective measures for protecting metal surface against corrosion in acidic environments. In this research, the inhibition effect of carboxymethyl cellulose (CMC) on the corrosion of aluminum in 2 M H2SO4 solution has been investigated by open circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) techniques. The results of the experiments show that CMC inhibits aluminum corrosion in 2 M H2SO4 solution, and the inhibition efficiency enhances with increasing concentration of CMC. The polarisation curves indicated that the CMC protection mechanism is a mixed type inhibitor in sulphuric acid solution. Also the inhibition category under this condition belongs to geometric blocking metal surface. In addition, the analysis on the morphology and composition of the aluminum surface suggests that CMC molecules through their polar functional groups physically absorb on the aluminum surface and form a protective and stable layer on the aluminum surface and prevent its corrosion.