Development of Polyacrylamide as a Potential Corrosion Inhibitor for Mild Steel in Acidic Medium

Abstract

We studied the effect of polyacrylamide (PAAM) on mild steel (MS) corrosion in hydrochloric and phosphoric acid using SEM, PDP, and EIS. Our findings showed that PAAM's inhibition efficiency increases with its concentration but decreases with rising temperatures. PDP results indicated that PAAM acts as a mixed inhibitor in HCl and a cathodic inhibitor in H3PO4. EIS data confirmed that adding PAAM to these corrosive environments reduces double-layer capacitance and increases charge transfer resistance, supporting its role as an effective inhibitor. Activation enthalpy and entropy values suggest that PAAM's inhibition is linked to its adsorption on the MS surface. SEM analysis verified this adsorption, which follows the Langmuir isotherm model. Additionally, DFT calculations and both Monte Carlo (MC) and molecular dynamics (MD) simulations provided deeper insights into the adsorption mechanisms and efficiency of PAAM as a corrosion inhibitor. This comprehensive study highlights the potential of PAAM for protecting MS in acidic conditions.