Synthesis of polyaniline tannate-modified carbon nanotubes by oxidative copolymerization as highly efficient corrosion inhibitors for mild steel in HCl solution

Corrosion is a prevalent issue in industrial production, directly impacting the production process and causing severe damages. To mitigate this problem, corrosion inhibitors are highly desired. Herein, a novel type of nano corrosion inhibitor, referred to as PTCNT, was synthesized through an oxidative copolymerization method utilizing aniline, ammonium persulfate (APS), and tannic acid (TA)-modified multiwalled carbon nanotubes (MWCNTs). The results demonstrated that the PTCNT effectively inhibited the corrosion of mild steel in 1 M HCl solution, achieving the corrosion inhibition efficiency of 90.6 % at the concentration of 75 mg/L. Characterization results implied that the PTCNT adsorbed onto the surface of the mild steel, forming a protective shielding layer. Potentiodynamic polarization measurements proved that the PTCNT functioned as the hybrid corrosion inhibitor. Furthermore, the adsorption of PTCNT on the mild steel surface was investigated using adsorption isotherm and adsorption kinetic modeling. Quantum chemical calculations were used to elucidate the adsorption mechanism of PTCNT. These findings raise new avenues for the development of highly efficient corrosion inhibitors for the mild steel in HCl solutions.