Evaluation of nonionic surfactants from plastic waste as corrosion inhibitors of carbon steel in 1M HCl

摘要

Recycled poly (ethylene terephthalate), PET, can be modified to produce nonionic surfactants. Recycling of PET waste was carried out in presence of triethanolamine (having 1:1 wt % of TEA : wt % of PET) and manganese acetate as catalyst. The produced oligomers were reacted with stearic acid and polyethylene glycol, PEG, which have differentmolecular weights 400, 1000 and 4000. The inhibition of corrosion of steel in 1 molar hydrochloric acid solution in the presence of the prepared surfactants is studied byweight loss and electrochemical polarizationmeasurements. 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 criticalmicelle concentrations. The temperature effect on the corrosion behavior of steel in 1M 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. The obtained results from weight loss and potentio-dynamic polarization techniques are in a good agreement.