Electrochemical and gravimeter study on corrosion inhibition by (methoxymethyl) triphenylphosphonium chloride in acid media H2SO4 0.5M

In this work, we study the inhibitory efficacy of organometallic compounds (phosphonium salts) used as an inhibitor on the corrosion of carbon steel XC70. The compound is (methoxy methyl) triphenyl phosphonium chloride (MMTP Cl). The study was performed in a 0.5M H2SO4 media. The measurements were performed by three electrochemical methods: electrochemical impedance spectroscopy potentiodynamic polarization and gravimeter method. One of the most widely used methods of protecting metals against corrosion is the use of inhibitors. They act by adsorption on the metal surface. The effectiveness of the corrosion inhibitor has been evaluated by several methods; polarization technique (Tafel line); electrochemical impedance and mass loss spectroscopy (immersion test) in acidic media. The results have allowed us to deduce the steel corrosion rate as well as other electrochemical parameters. The overall results show that the compounds (MMTP Cl) was chemically adsorbed on the steel surface. And in this case, adsorption occurs on the surface of the metal, according to the Langmuir modelin 0.5M H2SO4 solution. And the best concentration that decreasing the corrosion rate and gives inhibitory efficacy is 1ppm (R = 74.19%). A Comparative electrochemical study with that reported in the literature revealed that the efficiency of the inhibitors follows the order: 1-butyl triphenyl phosphonium chloride> (chloromethyl) triphenyl phosphonium chloride (CTP)>tetraphenyl phosphonium chloride (TP)>triphenyl phosphine oxide (TPO) > triphenyl (phenyl methyl) phosphonium chloride (TPM). It was also reported in the literature that the efficiency of halide inhibitors follows the order: I-> Br->Cl->F-.