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Rola elektrochemii w ochronie środowiska

Grodzka E., Winkler K., Koczorowski Z.

Wiadomości Chemiczne

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2006

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[Z] 60, 9-10

671-702

EN

For decades electrochemical technology has contributed successfully to environmental protection. Electroanalytical techniques have been frequently used in monitoring the changes of environment. In industry, electrochemical technologies can provide higher purity in technological processes and they can also limit a degradation of the environment in comparison to the common chemical methods. Electrochemistry has been also very useful in developing and in the production of new energy sources. A lot of attention has been paid to studies of environmentally friendly hydrogen fuel cells. The electrochemical techniques of waste degradation can be divided into two main categories: (i) techniques based on the faradaic processes of oxidation or reduction of contamination, and (ii) electrokinetic methods based on the transport of ions or charged particles in the electric field. The electrode processes result in the formation of deposits on the electrode surface or the decomposition of large organic molecules to the low molecular weight, easily biodegradable molecules or CO2. The electrokinetic techniques include electrocoagulation, electroosmosis, electrodialysis, and electroflotation. These techniques are widely used in removing contaminants from soil. This paper is focused on selected topics related to the environmentally friendly application of electrochemistry.

2

Electrochemical Formation of Two-component Films from 2'-Ferrocenylpyrrolidino[3',4' ; 1,2][C60]fullerene and Transition Metal Complexes

Płońska M., Makar A., Winkler K., Balch A.

Polish Journal of Chemistry

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2004

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Vol. 78 / nr 9

1431-1447

EN

Redox active films have been generated electrochemically by reduction of the chemically modified fullerene, 2_-ferrocenyl-pyrrolidino[3_,4_;1,2][C60]fullerene - FcC60, and [Pt(_-Cl)Cl(C2H4)]2 or Ir(CO)2Cl(p-toluidine). The film is believed to consist of polymeric network formedvia covalent bonds between the metal atoms and the fullerene moieties. Ferrocene is covalently linked to the polymeric chains through the pyrrolidine rings. The FcC60/Pt film is electrochemically active in both positive and negative potential ranges. At positive potentials, oxidation of the appended ferrocene is observed. In the negative potential range, electron transfer processes involving the fullerene take place. FcC60/Pt films exhibit higher permeability to anions than to cations. Only an outermost layer of this film is reduced. During the oxidation of the film significant structural changes occur. Film formation is also accompanied by platinum deposition. The present of a metallic phase in the film influences its morphology, structure and electrochemical properties. An FcC60/Ir film has been formed during reduction of solutions containing both FcC60 and Ir(CO)2Cl(p-toluidine). The yield of this film is low with only very thin layer deposited on the electrode surface. No electrochemical activity of the electrode modified with FcC60/Ir was detected in acetonitrile containing only supporting electrolyte.

3

Sonoelektrochemia : wpływ ultradźwięków na przebieg procesów elektrodowych oraz ich praktyczne wykorzystanie w elektrochemii

Winkler K., Wysocka M.

Wiadomości Chemiczne

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2002

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[Z] 56, 11-12

895-930

EN

Sonoelectrochemistry is the field of the research dealing with the influence of power ultrasound on electrochemical processes. The dominant effect of the ultrasound in electrochemical systems is the enhancement of mass transport by macrostreaming due to the propagation of an acoustic wave and microstreaming related to the acoustic cavitation phenomena and microjetts formation on the electrode surface. These effects are responsible for large enhancement of the current and significant modification of voltammograms recorded at stationary electrodes. In the presence of power ultrasounds voltammograms show steady-state sigmoidal shape with an oscillatory behavior. A simple planar diffusion layer model may be employed to analyze the current data. Ultrasound can also influence physical and chemical properties of electrode surface. Cavitation induced by ultrasound as well as shear forces can cause cleaning of the electrode surface and prevent adsorption and precipitation processes. Sonication can activate the electrode surface, too. High power ultrasound can also change the morphology of the electrode surface. Ultrasounds are succesfuly applied to a wide range of electrochemical technologies. There are frequently used in electrometalurgy for metal coating, electropolishing, electromachining, and electrochemical etching. The use of ultrasound allow eleiminate highly toxic compounds from the electroplating procedures. Ultrasound can significantly improve electrochemical synthesis processes. These improvements include enhancment diffusion and trerefore increase of yields and current efficiency, suppresed electrode fouling and alteration of reaction mechanism, and product selectivity control. Polymer films formed at the electrode surface in sonicated solution show better morrphology and mechanic properties. High rate of mass transfer under sonoelectrochemical conditions allows kinetic study of fast heterogeneous charge transfer processes and chemical steps coupled with rlectron transfer reaction. The application of ultrasound to analytical procedure can provide numerous benefits of which enhanced mass transport and in situ cleaning of the electrode are the most important. Sonoelectrochemistry analytical methods exhibit high sensitivity and good reproducibility. There are also less time consuming procedures comparison to conventional electroanalytical methods prformed under silent conditions. Ultrasound allows the formation of emmulsions in heterogeneous systems of immiscible organic and aqueous solvents without stabilizing agents simply by mechanical forces atributed to cavitation processes which arise at the liquid/liquid phase boundaries. Sonoelectrochemical is also used in nanotechnology for formation of nano-size metalic and non-metalic particles. The electrochemical study of electrode reactions of organic reagents in polar water solution can be carried out in these systems. Emulsions stabilized by ultrasound can be also used in quantitative analysis of water insoluble samples.

4

Electrochemical Properties of Fullerene Based Solid Thin Layers

Winkler K., Costa D., Balch A.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 1

1-37

EN

This paper reviews the results of investigations into the electrochemical properties of fullerenes and their derivatives in solid state. These systems can be divided into three groups: (i) polycrystalline thin layers, (ii) non-crystalline films, and (iii) fullerene based polymers. The effects of the supporting electrolyte and solvent on the electrochemical behavior of polycrystalline fullerene thin layer films are discussed.