Thiosemicarbazide, phenyl isothiocyanate and their condensation product as corrosion inhibitors of copper in aqueous chloride solutions

Re‐examination of the adsorption and reduction processes of thiosemicarbazide at a silver electrode: SERS, UV–visible and capillary electrophoresis studies

“…This result also suggests that a reduction of TSC has not occurred in acidic medium. 3 concentration, showing that it is possible to separate unequivocally the two compounds. The compounds were detected around the maximum absorption (250 nm).…”

“…Figure 1(B) shows the SERS spectra of TSC on a silver electrode in 0.1 mol dm 3 KCl solution. In the SERS spectra obtained in the potential range from 0.0 to 0.4 V, the most intense bands at 1018, 1293, 1462, 1507 and 1591 cm 1 (spectrum at 0.0 V) can be assigned to modes of the hydrazinic (H 2 NNH) and NCN groups of TSC.…”

“…This observation leads to the assignment of (AgS) to the band at 240 cm 1 and the 310 cm 1 band to the internal mode of TSC adsorbed on silver electrode in all electrolyte solutions. The reduction process of TSC adsorbed on a silver electrode in 1.0 mol dm 3 HCl was monitored by SERS. The behavior of the relative intensities of the H C TSC bands (Fig.…”

“…To speed up the analysis, the TU migration was assisted by a combination of applied voltage and pressure. Figure 6(B) presents the electropherogram of a TSC solution prepared in 1 mol dm 3 HCl subjected to electrolysis at 0.7 V for 40 min. According to what has been proposed by Loo et al, 12 under those conditions, the reduction of TSC should have occurred, resulting in the formation of TU and ammonium ion.…”

“…6(B), TU is not detected, indicating that the reduction of TSC does not occur at this potential. Figure 6(C) and (D) show the electropherograms of a TSC solution prepared in 3 mol dm 3 HCl and subjected to electrolysis at 0.1 and 0.7 V for 40 min, respectively. Again, only the TSC band is observed, indicating that TU is not formed, even in more acidic solution.…”