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Inhibition of Alkaline Corrosion of Aluminium and Zinc by Condensation Products of Some Carbonyl Compounds
Author(s) -
Khamis E.
Publication year - 1997
Publication title -
materialwissenschaft und werkstofftechnik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.285
H-Index - 38
eISSN - 1521-4052
pISSN - 0933-5137
DOI - 10.1002/mawe.19970281116
Subject(s) - chemistry , zinc , adsorption , aluminium , metal , ketone , condensation reaction , corrosion , crotonaldehyde , condensation , inorganic chemistry , organic chemistry , catalysis , thermodynamics , physics
The inhibitory effect of the condensation products of thiosemicarbazide (TSC) with furfruldehyde (FrA), Crotonaldehyde (CrA) or methyl vinyl ketone (MVK) was investigated as corrosion inhibitors for aluminium and zinc in 0.5 M NaOH using gasometry and d.c. polarization technique. Correlation of the structural changes with the protection efficiency of CrTSCN MVTSCN and FrTSCN with the parent TSC Was reported. The experimental results indicate that the presence of adsorbed inhibitors on aluminium or zinc surfaces does not affect the mechanism of hydrogen evolution. Furthermore, polarization curves show that the compounds act as mixed‐type inhibitors. Variation of the protection efficiency is evident fo the different compounds, with increase of π‐electron density of the center of adsorption, by addition of double bonds or by heterocyclic ring, contributing to improvement in protection effieciency. All data were compared and fitted to kinetic‐thermody‐namic model. The number of active sites on the metal occupied by a molecule of the inhibitor and the binding constant of the inhibitor to the active site were calculated for the investigated compounds. The results are compared with fits obtained from the application of other adsorption isotherms.