Preparation and Characteristics of Starch Nanocrystals as Corrosion Inhibitor: Experimental and Theoretical Studies

Abstract

Technological advances have led to sophisticated computer software and programs, along with mathematical and experimental techniques, to envisage corrosion inhibition. Using potentiodynamic polarization measurements, weight loss techniques and quantum chemical calculations, the corrosion inhibition of mild steel was explored in 1 M HCl by employing novel inhibitor starch nanocrystals (SNCs). The structures of starch and its nanocrystals were investigated by FESEM, FTIR, AFM and TEM techniques. In presence of 0.5 g/L SNCs at 293 K, the maximum inhibition efficiency (%IE) was 67%. The results showed that the novel SNC inhibitor follows the Temkin adsorption isotherm. The activation energy, Gibbs free energy, enthalpy and entropy of adsorption were calculated. Quantum chemical calculations further helped to understand the SNC inhibition mechanism through density functional theory (DFT) to estimate possible active centres that could be responsible for SNC adsorption on the surface of mild steel. Moreover, quantum chemical descriptors were computed. The findings indicated that SNCs show a high efficiency for corrosion inhibition.