Synthesis of a Gemini-Mannich base efficient corrosion inhibitor for oilfield acidification.

The gemination of functional groups is an effective way to enhance corrosion efficiency. A Gemini-Mannich base corrosion inhibitor (BPFC), exhibiting superior solubility and corrosion inhibition efficacy, was synthesized via a one-step process from piperazine, cyclohexanone, and formaldehyde as reactants. BPFC exhibits outstanding corrosion inhibition in 5% HCl, with maximum inhibition efficiency observed at 353 K. At 2.11 × 10-2 M concentration, BPFC reduces the corrosion rate to 1.86 mg cm-2 h-1, corresponding to a corrosion inhibition efficiency of 92.66%. BPFC functions as a mixed-type inhibitor, which concurrently inhibits anodic dissolution processes and cathodic hydrogen evolution reactions. Adsorption of BPFC on metallic surfaces follows the Langmuir adsorption isotherm, with physical adsorption mechanisms predominating. Quantum chemical calculations and molecular dynamics simulations reveal the inhibitory mechanism of BPFC, highlighting the role of tertiary amine groups and CO functionalities. These groups provide lone pair electrons for coordination with metal d orbitals, facilitating adsorption on the metal surface and obstructing the interaction between corrosive ions and the metal substrate.