Ganesha Achary

Surface treatment of zinc by Schiff’s bases and its corrosion study

The zinc metal surface is chemically modified by newly synthesized Schiff’s bases and its corrosion protection is investigated. The influence of concentration of Schiff’s bases on modification of zinc surface and immersion time in treatment bath are investigated and optimized for maximum corrosion protection efficiency. The electrochemical studies of treated zinc specimens are performed in aqueous acid solution using galvanostatic polarization technique. The treated zinc samples show good corrosion resistance. The recorded electrochemical data of chemically treated samples indicate a basic modification of the zinc surface. The protection efficiency of organic layer formed on zinc surface is tested by varying the acid concentration and temperature of the corrosive medium. The corrosion protection efficiency increases with the concentration of Schiff’s bases and immersion time. This is due to a strong interaction between zinc and the organic molecules, which results in the formation of a protective layer. This layer prevents the contact of aggressive medium with the zinc surface. The surface modification is confirmed by the scanning electron microscopy images. The interaction between metal atoms and Schiff’s bases is also established by IR studies.

Surface Modification of Zinc with an Oxime for Corrosion Protection in Chloride Medium

The surface treatment of zinc was done with different concentrations of an oxime (2E)-2-(hydroxylamino)-1,2-diphenylethanol molecule by the immersion method. The electrochemical corrosion studies of surface-treated zinc specimens were performed in aqueous sodium chloride solution (1 M, pH 5.0) at different temperatures in order to study the corrosion mechanism. The recorded electrochemical data indicated a basic modification of the cathodic corrosion behavior of the treated zinc resulting in a decrease of the electron transfer rate. The zinc samples treated by immersion in the inhibiting organic solution presented good corrosion resistance. Using scanning electron microscopy (SEM), it was found that a protective film was formed on the surface of zinc.

Electrochemical preparation of orthophenylenediamine on different cathodes in sulfuric acid

The electrochemical reduction of nitro group of orthonitroaniline (ONA) is carried out on Pb, Cu, and Sn electrodes. The effect of current density, temperature, and acid concentration on product yield is studied. The polarization curve for ONA in acidic condition is recorded. Under preparative electrolysis, ONA gives a mixture of hydroxylamine and phenylenediamine, the proportion of phenylenediamine increasing with the electrolysis time. The product formation is confirmed by thin-layer chromatography, melting-point test, UV-visible, IR, and NMR methods. The operating conditions are optimized for a good yield of orthophenylenediamine. The catalytic activity of different metals for the reduction of nitro group is discussed. The percent yield of orthophenylenediamine is found to be high on the lead electrode.