Inhibition of corrosion of aluminium in alkaline medium by glutaric acid in conjunction with zinc sulphate and diethylene triamine penta (Methylene phosphonic acid)

Shanmugam Rajendran*, C. Thang

Abstract

The inhibition efficiency (IE) of glutaric acid (GA) in conjunction with Zn2+ and diethylene triamine penta (methylene phosphonic acid) [DTPMP] on the corrosion of aluminium in 0.5M NaOH was investigated by weight loss and electrochemical techniques. The ternary system GA (1000 ppm) – Zn2+ (20 ppm) - DTPMP (20ppm) has 93.4% IE. IE values calculated from electrochemical polarization studies were in good agreement with those calculated from weight loss studies. ΔG values were calculated from surface coverage values. Effect of temperature on the IE was also studied from which Ea and ΔH were computed. Surface morphology studies were done using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The inhibitors act as mixed inhibitors and obey Langmuir adsorption isotherm.