A SERS investigation of carbon steel in contact with aqueous solutions containing BenzylDiMethylPhenylAmmonium Chloride

The electrochemical behaviour of carbon steel in contact with a neutral sulphate solution containing BenzylDiMethylPhenylAmmonium Chloride (BDMPAC), a potential non-toxic corrosion inhibitor was investigated by Surface Enhanced Raman Spectroscopy (SERS) and linear sweep voltammetry. Sound surface enhancement was obtained by potentiostatic polarisation without special electrochemical pretreatments. Potential-dependent Raman spectra highlighted the electrodic behaviour of the adsorbate: in the range - 1200 ÷ - 900 mV (Ag/AgCl), adsorption takes place with the benzyl ring interacting with the surface in a flat configuration, as indicated by the presence of the Ph-CH 2 combination band located near 1215 cm -1 . Linear sweep voltammetry testifies the difference in measured currents between sulphate containing solutions in the absence and the presence of BDMPAC at the adsorption potentials. The formation of iron corrosion products was easily detected by in situ Raman spectroscopy.