Corrosion Inhibitor Release from Zn-Al-[PO43-]-[CO32-] Layered Double Hydroxide Nanoparticles

Zn-Al layered double hydroxide (LDH) nanoparticles with carbonate as the charge balancing anion in the interlayer space were synthesized using co-precipitation method. Then, the carbonate base Zn-Al LDH nanoparticles were doped with phosphate ion via anion-exchange reaction to synthesize Zn-Al-[PO43-]-[CO32-]. The structure and composition were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric-differential thermal analysis (TG-DTA). Inductively coupled plasma-optical emission spectrometer (ICP-OES) was employed to measure the phosphate release ability of Zn-Al-[PO43-]-[CO32-] in the 3.5 wt% NaCl solution. Results showed that zinc cation can release along with phosphate anion during ion exchange process. Then, the corrosion inhibition of phosphate anion and zinc cation on mild steel specimens was assessed by electrochemical impedance spectroscopy (EIS) and polarization. Field emission-scanning electron microscopy (FE-SEM) was used to study the surface morphology of the mild steel specimens after exposure to the test solutions. The results indicated the significant impact of zinc and phosphorus concentration in test solution on the corrosion inhibition properties. Prog. Color Colorants Coat. 9 (2016), 231-246© Institute for Color Science and Technology.