High inhibition efficiency and hydrogen permeation for novel N-heterocycles of SAE 1020 in HCl solution

Document Type

Article

Publication Date

7-22-2025

Department

Department of Physics

Abstract

To safeguard carbon steel during industrial acid pickling, it is essential to create corrosion and atomic hydrogen embrittlement inhibitors that are effective, non-toxic, and easily produced. Here, we synthesized and investigated the efficacy of 2-(nitromethylene)-1,3-oxazinane (NOX) and 2-(nitromethylene)hexahydropyrimidine (NHE) as corrosion inhibitors for SAE 1020 steel in 1.0 mol L−1 HCl aqueous solutions, within a concentration range of 3.7 mmol L−1 to 4.0 mmol L−1. For both inhibitors were obtained, an efficiency up to 82.7% (91.5%) for NHE (NOX), respectively. The NOX compound exhibited a 42.80% inhibitory efficacy of atomic hydrogen permeation. An anomalous behavior was noted in NOX, depending on its concentrations, leading to efficiency reduction. Theoretical calculations were performed using Density Functional Theory (DFT), where it was demonstrated that NOX is an energetically preferable molecule and has smaller binding energy compared with NHE. Two distinct concentrations of NOX molecules were examined, and at a higher concentration, an oxygen atom is released from the molecule and binds to the Fe surface. This phenomenon does not occur at low concentrations, and is ascribed to the anomalous behavior of the NOX molecule. Our finding paves the way for novel and high-efficiency N-heterocycle inhibitors.

Publication Title

Journal of Industrial and Engineering Chemistry

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