Ethoxylates nonionic surfactants as promising environmentally safe inhibitors for corrosion protection of reinforcing steel in 3.5 % NaCl saturated with Ca(OH)2 solution

Abstract

Herein, the anti-corrosive action of two Ethoxylates nonionic surfactants, namely isodecyl alcohol ethoxylates (IAE) and nonylphenol ethoxylates (NPE) for reinforcing steel in 3.5 %NaCl saturated with Ca(OH)2 solution was assessed. Electrochemical measurements, surface examination, quantum chemical calculations and Monte Carlo (MC) simulations were investigated. The potentiodynamic polarization studies inferred that the examined inhibitors act as anodic type inhibitors. The adsorption of IAE and NPE on reinforcing steel surface follows Langmuir isotherm which resulted in pronounced corrosion resistance with reduced corrosion rate. The inhibition effect of the surfactants on the reinforcing steel surface was confirmed by SEM and AFM results. The corrosion inhibition tendency for the investigated surfactants was evaluated by employing the quantum calculations. While the interaction energy among the surfactant molecules and the metal surface was evaluated using MC simulations. The surfactants were found to be parallelly adsorbed on the Fe (110) surface which maximizes their contact with the steel surface as predicted using MC simulations. The results of different techniques are further used to ascertain the corrosion mechanism and also the adsorption mode of inhibitors in details. The results of theoretical studies validate the experimental studies with superior inhibition efficiency of NPE greater than IAE.