Pectin-amino acid derivatives as highly efficient green inhibitors for the corrosion of N80 steel in CO2-saturated formation water

Pectin, as the raw material from the waste peel and residue of various plants, was applied to prepare an environmentally friendly, inexpensive, and biodegradable green modified-pectin (P-Gly and P-Lys) corrosion inhibitor. Elemental analysis, FTIR spectroscopy, 1H NMR and XRD analysis confirmed the grafting degrees of amidated pectin were 6.26% (P-Gly) and 7.20% (P-Lys), respectively. The corrosion inhibition mechanism of P-AAs on N80 carbon steel in CO2-saturated groundwater was investigated. It was found that P-AAs showed high corrosion inhibition efficiencies at a low concentration of 800 mg/L: P-Gly (99.01%) and P-Lys (99.36%) with excellent adsorption stability maintained for 120 h. Theoretical calculations including QC based on DFT and GFN-xTB methods and MD-based RDFs revealed the chemisorption of the inhibitors on the Fe surface.