Influence of temperature and applied potential on the permeability of polyphenol films prepared on vitreous carbon in ac
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ORIGINAL PAPER
Influence of temperature and applied potential on the permeability of polyphenol films prepared on vitreous carbon in acid and alkaline media Noureddine Belhadj Tahar • Andre´ Savall
Received: 28 November 2012 / Accepted: 19 March 2013 / Published online: 30 March 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract The electrochemical polymerization of phenol is known to rapidly produce a thin insulating film at the anode surface. This film generally blocks further polymerization. The objective of this study is to show that, depending on the operating conditions, polymeric films resulting from phenol oxidation present different properties and that certain films can be so porous that they allow the oxidation of phenol to continue. The deposition of polyphenol films with improved permeability could be attractive in the removal of phenol from polluted solutions. Polyphenol films were prepared in aqueous solution on a vitreous carbon anode either by cyclic voltammetry or by electro-oxidation at constant potential. The apparent permeability P (%) of the films prepared by these techniques was evaluated by monitoring changes in the electrode response towards phenol and potassium ferricyanide at 25 and 85 °C and as a function of the potential applied during electropolymerization performed either in acidic (1 mol L-1 H2SO4) or in alkaline (1 mol L-1 NaOH) aqueous solution. It was shown that: (1) the polyphenol film electrosynthesized in alkaline medium was more permeable than that prepared in acidic medium, (2) the apparent permeability was higher when the polyphenol film was electrosynthesized with simultaneous oxygen evolution and (3) the use of a high temperature in the polyphenol film preparation, especially in
N. Belhadj Tahar Institut Supe´rieur des Sciences Applique´es et Technologie de Mahdia, Universite´ de Monastir, Monastir, Tunisia e-mail: [email protected] A. Savall (&) Laboratoire de Ge´nie Chimique, CNRS, Universite´ Paul Sabatier, 118, Route de Narbonne, 31062 Toulouse cedex, France e-mail: [email protected]
the presence of a concomitant oxygen evolution, significantly enhanced its apparent permeability (P C 100 %). These results are interpreted in terms of a mixed-transport mechanism involving both pore and membrane diffusion. The effect of the permeability of the polymeric film on the removal of phenol from aqueous solution by electropolymerization is discussed. Keywords Phenol Vitreous carbon Electropolymerization Permeability Electrochemical depollution
1 Introduction Electrochemical oxidation of phenolic compounds is well known to cause the inactivation of various electrode materials by the deposition of an adherent, compact, insulating film formed by polymerization [1–6]. Thus, polymeric films formed during the oxidation of phenolic compounds have been generally regarded as a cumbersome problem in electrochemical wastewater treatment processes. However, electropolymerization of phenol involving less than two electrons per molecule [7, 8] could be cons
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