XXIII Congress of Chemists and Technologists of Macedonia ________________________________________________________________
EC 004 MODIFICATION OF IRON SURFACE WITH HETEROCYCLIC DIAZONIUM SALTS. APPLICATION TO IRON PROTECTION AGAINST CORROSION Avni Berisha1, Fetah Podvorica1, Valbonë Mehmeti1, Fatos Rexhepi2, Fidan Syla1, Debatik Vata1 e-mail:
[email protected] 1 - University of Prishtina ‘’Hasan Prishtina’’, FNMS, Chemistry Department, str. “Nëna Tereze” nr. 5, 10000 Prishtina, Republic of Kosovo. 2 - University of Mitrovica “Isa Boletini” Industr. Park Trepça 40000, Mitrovica, Republic of Kosovo
The electroreduction of aryl diazonium salts permits the formation of aryl radicals that are able to react immediately with material surface and to form thin nanometric films onto conducting, semi conducting and insulating surfaces. These grafted organic moieties are covalently bounded and may contain different functional groups, which can give rise to functionalized surfaces with specific properties.
Figure 1. Schematic representation of: A. ‘’ in situ ‘’transformation of amino heterocyclic compound to corresponding diazonium salt and B. grafting of this diazonium salt onto iron surface. In this study we have created covalently bonded films onto iron surface by electroreduction of heterocyclic diazonium salts prepared “in situ” from their corresponding amines. In the first step, by using ATR-IR (diamond crystal) and UV-VIS spectroscopy, we have observed the complete transformation of the heterocyclic amines into diazonium salts in aqueous acid medium in the presence of sodium nitrite (Figure. 1.A). Then the surface of the iron is grafted with organic layers derived from heterocyclic diazonium salts by imposing a negative potential to the iron electrode (cyclic voltammetry) (Figure. 1.B). The efficiency of these strongly grafted layers onto iron surface to protect its surface against corrosion is tested by potentiodynamic measurements. Polarization curves indicate the decrease of corrosion rate of modified iron electrodes immersed in aqueous acid medium. Key words: corrosion inhibition, heterocyclic diazonium salts, ATR-IR spectroscopy, grafting, surface modification.
