Corrosion Inhibition by Malonic Acid

The inhibition efficiency of malonic acid is controlling corrosion of Aluminium in an aqueous solution at pH 10, in the absence and presence of Zn2+ has been evaluated by weight loss method. The formulation consisting of 250 ppm of malonic acid and 50 ppm of Zn2+ has 90 % corrosion inhibition efficiency. A synergistic effect exits between malonic acid and Zn2+. The mechanistic aspects of corrosion inhibition have been studied by electro chemical studies such as polarization study and AC impedance spectra. In the presence of inhibitor linear polarization resistance increases and corrosion current decreases. The protective film formed has been analysed by FTIR spectroscopy. The protective film consists of aluminium-malonic acid complex. There is also possibility of zinc-malonic acid complex.