Combined Experimental and Theoretical Insights into the Corrosion Inhibition Activity on Carbon Steel Iron of Phosphonic Acids

Abstract

The inhibition effect of N,N′-phosphonomethylglycine (PMG) and vinyl phosphonic acid (VPA) on the 3% NaCl acidic solution corrosion of carbon steel iron was studied at different immersion times by potentiodynamic polarization, electrochemical impedance spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and computational methods. It is found from the polarization studies that PMG and VPA behave as mixed-type inhibitors in NaCl. Values of charge transfer resistance (Rct) and double layer capacitance (Cdl) in the absence and presence of inhibitors are determined. The PMG and VPA inhibitors were capable of inhibiting the corrosion process up to ≈91% and ≈85%, respectively. In the presence of PMG, the synergic effect of chlorine ions was observed. Density functional theory (DFT) was engaged to establish the adsorption site of PMG, VPA, and their deprotonated states. For studied compounds, the resulted values of ELUMO, EHOMO, energy gap (∆E), dipole moment (μ), electronic hardness (η), global softness (σ), electrophilic index (ω), and the electronic potential map are in concordance with the experimental data results regarding their corrosion inhibition behavior and adsorption on the metal surface.

Performance of ionic liquid functionalized metal organic frameworks in the adsorption process of phenol derivatives

“…The yield was calculated based on the metal salt: (yield: CoHEDP, [Co(HEDP) 2 (H 2 O) 2 ]2H 2 O: 76%; NiHEDP, [Ni(HEDP) 2 (H 2 O) 2 ]2H 2 O: 55%; CuHEDP, Cu(HEDP) 2 (H 2 O) 2 : 63%; CeHEDP, Ce(HEDP)(H 2 O)]3H 2 O: 69%). 26,39–43…”

Two Steady-State Adsorption Modes of Phosphonic Acids on Aluminum Surfaces

“…The energy gap (Δ E ) is also calculated from the energy difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO): Δ E = E HOMO – E LUMO .…”

Hybrid Coordination Networks for Removal of Pollutants from Wastewater

“…Then, the clear white or violet solution was heated in an oil bath at 80 °C for 75 h, unperturbed. After 75 h heating, crystalline white (CaCEPPA) and black crystals (CoCEPPA) were isolated by filtration and, finally, air dried (yield: 62–70%) [ 55 , 56 , 57 ].…”