Derivatives of [P4-VP] 2% DVB as corrosion inhibitors for St-37 in 1 M H2SO4: an experimental and theoretical investigations

Abstract

Poly (4-vinyl pyridine) cross-linked by 2%DVB quartenized by I−, Br−, N3 − and SCN−; named [P4-VP]MI, [P4-VP]BBr, [P4-VP]MN3, [P4-VP]MSCN are synthesized and their effect as a new eco-friendly polymeric inhibitor on the corrosion process of St-37 in 1 M H2SO4 at ambient temperature was investigated. Fouriertransform infrared spectroscopy (FT-IR), energy dispersive X-ray (EDX) and scanning electron microscope (SEM) techniques are used to confirm formation and the structure of the inhibitors. Then, their ability as corrosion inhibitors are examined by theoretical computation as well as the experimental tests involving potentiodynamic polarization (PDP), weight-loss measurements and electrochemical impedance spectroscopy (EIS). According to the obtained results, all inhibitors can effectively protect carbon steel from corrosion and the inhibition efficiency increases as the concentration of inhibitor and reaching 91.08% at 0.04 g L−1 [P4-VP]MI in 1 M H2SO4 and the corrosion current density reduces from 398.11 × 10−6 A·cm−2 in the blank condition to 35.48 × 10−6 A·cm−2. The geometrical and electronic properties of poly(4-vinylpyridine) cross-linked with 2% divinyl benzene and its derivatives as well as their corrosion inhibition process on Fe (1 1 0) surface are investigated using density-functional theory (DFT) and molecular dynamics (MD) simulation in water solution. The results of comparing the inhibitory efficiency of polymers show that the order of inhibition is as follows: [P4-VP]MI > [P4-VP]BBr > [P4-VP] MN3 > P4-VP > [P4-VP]MSCN.