Novel porphyrin derivatives as corrosion inhibitors for stainless steel 304 in acidic environment: synthesis, electrochemical and quantum calculation studies

A Novel 5,10,15,20-tetra (thiophen-2-yl) porphyrin (P1) and 5,10,15,20-tetrakis (5-Bromothiophen-2-yl) porphyrin (P2) were successfully synthesized, and their chemical structures were proved based on its correct elemental analysis and spectral data (IR and H-1-NMR). These compounds were examined as corrosion inhibitors for stainless steel 304 (SS304) in 2 M HCl utilizing mass reduction (MR) and electrochemical tests at inhibitor concentration (1 x 10(-6)-21 x 10(-6) M). The protection efficiency (IE %) was effectively enhanced with improving the concentration of investigated compounds and reached 92.5%, 88.5% at 21 x 10(-6) M for P1 & P2, respectively and decreases with raising the temperature. Langmuir's isotherm was constrained as the best fitted isotherm depicts the physical-chemical adsorption capabilities of P1 & P2 on SS304 surface with change in Delta G(ads)(o) = 22.5 kJ mol(-1). According to the PDP data reported, P1 and P2 work as mixed find inhibitors to suppress both cathodic and anodic processes. Porphyrin derivatives (P1 & P2) are included on the surface of SS304, according to surface morphology techniques SEM/EDX and AFM. Quantum calculations (DFT) and Monte Carlo simulation (MC) showed the impact of the chemical structure of porphyrin derivatives on their IE %.

Automated summary

A novel porphyrin derivative (P1) and its brominated analog (P2) were successfully synthesized and their corrosion inhibition properties on stainless steel 304 (SS304) were studied. The protection efficiency increased with increasing concentration of the compounds and Langmuir's isotherm provided the best fit for describing the adsorption capabilities on SS304 surface.