New hydrazine derivatives as corrosion inhibitors for mild steel protection in phosphoric acid medium. Part A: Experimental study

The inhibitory effects of three hydrazine derivatives,namely 1,2-bis(pyrrol-2-ylidenemethyl)hydrazine (hz1),1,2-bis(thiophen-2-ylidenemethyl)hydrazine (hz2) and 1,2-bis(furyl-2-ylidenmethyl)hydrazine (hz3) for the corrosion of mild steel in phosphoric acid solution was studied using weight loss (wl),electrochemical impedance spectroscopy (eis) and polarization curves (pc). it was found that the inhibition efficiency of the compounds increases with the increasing their concentration. the adsorption of inhibitors on the steel surface follows the langmuir isotherm. the effect of temperature on the corrosion behavior of mild steel in phosphoric acid solution in the absence and presence of the inhibitors was also studied. from the experimental data,some thermodynamic parameters were calculated and discussed. polarization curves showed that hz1,and hz3 behave as mixed type corrosion inhibitors in phosphoric acid solution.