Electro-oxidation of chlorophenols on powdered carbon electrodes of different porosity

Abstract

Activated carbons with large and medium-sized S BET , carbon blacks with different surface areas as well as graphite and heat-treated carbon of extremely low porosity were used in this study. Cyclic voltammograms were recorded for these materials in neutral electrolyte (0.1 M Na 2 SO 4 ) solutions containing various chlorophenols (CPs; 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol) as depolarizers. The changes in the FTIR spectra of the electrode materials caused by the adsorption and/or coupling of CPs (and/or their degradation products) were recorded. HPLC was used for analyzing the concentration of CPs and their degradation products. The dependence of the electrochemical behavior of CPs with various chlorine contents on the character of carbon materials is discussed. The possible mechanism of the initial stages of CP degradation by electro-oxidation/ reduction depends on the kind of electrode material. Since different carbons vary in their electrochemical behavior and in their voltammetric response to the presence of different CPs, the application of the method for selecting electrode materials better suited to removing organochlorine impurities from ground-water seems feasible. The efficiency of the process depends closely on the kind of carbon and on the tendency for its surface to become covered by a polymeric (conducting or nonconducting) film of electro-degradation products.

The removal of chlorophenols from aqueous solutions using activated carbon adsorption integrated with H2O2 oxidation

“…A variety of reaction by-products were observed to form during the oxidation of chlorophenols (e.g. phenols, quinones, catechols) and the degradation pathways and mechanisms for many of the oxidation processes have been proposed [37,[40][41][42][43][44]. Unfortunately, in this work, during the oxidation experiments, the additional peaks on the chromatograms were not observed, suggesting that the oxidation intermediates were rapidly adsorbed on the activated carbon.…”

A detailed kinetic study of the direct photooxidation of 2,4,6-trichlorophenol

“…In these cases, no dioxins are produced among the oxidation products [7], which is a major concern with other waste treatment methods, for example the direct incineration of solid chlorophenols. The use of ozone [5,6], Fenton's reagent [5], peroxidase enzyme [13], electrooxidation [21], or even simple absorption processes [22] are also possible alternatives in the abatement of chlorophenol-containing waste.…”

Studies on Carbon Materials Produced from Salts with Anions Containing Carbon Atoms for Carbon Paste Electrode

“…For comparison, in Table 1 , both parameter values for graphite G-SA used in CPEs are shown. These data show that the structure of both obtained carbon materials is intermediate between typical for graphite and carbon black [ 13 , 14 , 15 , 16 ]. The values of the interlayer spacing d 002 of the crystal structure and the number of layers NC presented in Table 1 show relatively small differences of these parameters for both carbons (C-AO and C-SB).…”