Synthesis and corrosion inhibition performance of a nitrogen- and phosphorus-containing inhibitor for carbon steel

In this article, we study the synthesis and evaluation of a novel compound derived from di(thio)amidophosphates and epichlorohydrin, designed as a potential corrosion inhibitor. The synthesis was optimized under a molar ratio of ۱:۱ of the starting materials, a reaction temperature of ۱۰۰ °C, and a reaction time of ۲.۵–۳ h, achieving yields between ۹۳.۶ and ۹۶.۳ %. Structural characterization by elemental analysis and IR spectroscopy supported the formation of functional groups responsible for corrosion inhibition, including P=O, P–H, C=O, and C=S groups. The corrosion inhibition performance was studied using combined experimental methods using gravimetric, electrochemical polarization, and surface analysis techniques. In ۱ M HCl solution, potentiodynamic polarisation (PDP) measurements revealed a substantial reduction in corrosion current density (icorr) from ۱۰.۹۶ mA cm⁻² in the uninhibited system to ۰.۷۱ mA cm⁻² at an inhibitor concentration of ۱۵۰ mg L⁻¹, corresponding to a maximum inhibition efficiency (ηPDP) of ۹۴.۸۶ %. Additional gravimetric tests in CO₂- and H₂S-saturated NaCl solutions demonstrated inhibition efficiencies ranging from ۸۶ to ۹۷.۵ %, depending on pH, gas pressure, and inhibitor concentration. SEM and AFM analyses confirmed the formation of a compact, uniform protective film on the steel surface. These findings indicate that the synthesized compound exhibits strong potential as an effective corrosion inhibitor for industrial applications, providing a promising approach for the protection of metals under aggressive environmental conditions.

کلیدواژه ها:

di(thio)amidophosphates ، Epichlorohydrin ، SEM ، AFM ، carbonic anhydride ، Hydrogen Sulfide