INSITU RAMAN-SPECTRA OF PYRIDINE AND PYRIDINIUM CHLORIDE ADSORBED ON IRON IN K2SO4 AND H2SO4 SOLUTIONS

A study on adsorption behavior of organic compounds on iron in a sulfate solution is of importance to an investigation of their inhibition mechanism for iron corrosion in the solution. Surface-enhanced Raman scattering (SERS) spectra of pyridine and pyridinium chloride adsorbed on iron in 0.1M K2SO4 at pH 3.5 and 0.25M H2SO4 were measured using a SERS-active silver electrode covered with an iron layer of minimum thickness. It was concluded from the spectra that a pyridine molecule is chemisorbed on the iron surface in 0.1M K2SO4. A weak SERS spectrum of pyridinium ion adsorbed on iron was observed in 0.25M H2SO4 because of a low adsorbability of the ion on the iron surface in the solution.