Corrosion behavior and mechanisms of carbon steel in Cu(II)-amine based solvents for electrochemically mediated CO₂ capture system

Electrochemically Mediated Amine Regeneration (EMAR) carbon capture technology offers an energy-efficient and cost-effective alternative to traditional thermal-driven absorption methods attributed to its capability to utilize renewable energy and operate under ambient conditions. However, the corrosion susceptibility of carbon steel in Cu(II)-amine solvents poses critical challenges to EMAR system durability and economic viability. This work systematically evaluated the corrosion mechanisms of carbon steel in the Cu(II)-monoethanolamine (MEA) and Cu(II)-ethylenediamine (EDA) based solvents through four-dimensional comprehensive test: corrosion potential analysis (thermodynamic evaluation), electrochemical impedance spectroscopy (kinetic evaluation), weight-loss tests (macro-scale practical testing), and morphological characterization (microscopic perspective). Results reveal that in CO₂-free solutions, corrosion reactions predominantly mediated by organic amine molecules exhibit weaker activity, whereas under CO₂-saturated conditions, protonated amine and bicarbonate ions-dominated corrosion processes undergo significant intensification, leading to severe damage to the carbon steel surface. However, the introduction of cupric ions (Cu²⁺) substantially reduces the corrosion tendency regardless of CO₂ saturation status. Both the MEA and EDA based solutions follow the same trend, despite EDA exhibiting a higher overall corrosivity. In the Cu(II)-MEA and Cu(II)-EDA system, the carbon steel surface remains smooth, with a corrosion rate below 0.0041 mm/year, demonstrating a reduction exceeding 90% compared to traditional chemical absorption systems (corrosion rate > 0.0662 mm/year). The findings highlight the superior corrosion mitigation capability of the EMAR-CO₂ capture system compared to traditional CO₂ chemical absorption methods, providing critical insights for the practical application of EMAR-CO₂ capture technology.