Inhibitive Performance of Hydroxypropyl Cellulose and Potassium Iodide on the Corrosion of Mild Steel in Sulphuric Acid Environment

The inhibitive performance of hydroxypropyl cellulose (HPC) and and its combination with potassium iodide (KI) on mild steel corrosion in 0.5 M H2SO4 acid solution was studied using the potentiodynamic polarization, gravimetric measurement technique and theoretical computations. Weight loss results obtained indicate that the HPC and its combination with KI functioned as a good inhibitor in sulphuric acid environment with inhibition efficiency of 76.43% and 89.73% respectively, and inhibition efficiency increased with concentration. Changes observed in polarization parameters suggest the adsorption of HPC on the mild steel surface, leading to the formation of protective films. The adsorption characteristics of the inhibitor were approximated by Langmuir isotherm. Synergistic effect increased the inhibition efficiency in the presence of halide additives and the values of the synergistic factor with KI were higher than unity indicating that both additives act cooperatively to enhance inhibition performance. The Fukui functions revealed that HPC adsorbed on the corroding mild steel surface through multiple OH groups, propyl groups and aromatic structure. The experimental results corroborated with results from theoretical studies.