Nonionic Surfactants from Recycled Poly(ethylene terephthalate) as Corrosion Inhibitors of Steel in 1 M HCl

Recycled poly(ethylene terephthalate) (PET) can be modified to produce nonionic surfactants. Recycling of PET waste was carried out in presence of triethanolamine and manganese acetate as catalyst. The produced oligomers were reacted with stearic acid and polyethylene glycol, PEG, which have different molecular weights 400, 1,000, and 4,000. The inhibition of corrosion of steel in 1 molar hydrochloric acid solution in the presence of the prepared surfactants is studied by weight loss and electrochemical polarization measurements. The polarization curves indicate that these compounds act as mixed‐type inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration to reach their critical micelle concentrations. The temperature effect on the corrosion behavior of steel in 1 M HCl with and without surfactants is studied in the temperature range from 308 to 343 K. The adsorption of inhibitors on the steel surface is found to increase with increasing the temperature. From the adsorption isotherm, some thermodynamic data for the adsorption process are calculated and discussed.