Electrochemical Oxidation of Dyeing Baths Bearing Disperse Dyes

Abstract

This paper presents the results of the electro-oxidation of pollutants in synthetic textile wastewater containing partially soluble disperse dyes. The experiments were performed in an electrochemical undivided cell reactor using seven different anode materials and 0.1 M NaCl as the supporting electrolyte. With the Ti/Pt-Ir anode, which showed the best performance among all the tested materials, additional experiments were also carried out using 0.05 M Na 2 SO 4 as the supporting electrolyte. Experimental results obtained in the electrochemical reactor, supported by the data obtained during cyclic voltammetry studies, showed that under the conditions of the present research the removal of pollutants was mediated by active chlorine generated by electro-oxidation of chloride ions or by other mediators generated in situ and not by a direct discharge of pollutants at the anode. Under the conditions of free pH evolution 39% removal of chemical oxygen demand was obtained after 40 min of electrolysis. The apparent pseudo-first-order rate constant for the removal of color was equal to 2.54 × 10 -4 s -1 and it increased to 8.23 × 10 -4 s -1 under pH control at the value of 4.5, resulting in 90% removal of color after the passage of 1.9 A h dm -3 . In comparative studies on the chemical oxidation of pollutants by hypochlorite far lower efficiency was obtained.

Carbon materials and catalytic wet air oxidation of organic pollutants in wastewater

“…Alternatively, low temperature oxidation processes replace oxygen by stronger oxidants such as O 3 [9,10] or H 2 O 2 [9,11,12] in combination with an energy input to form reactive OH-radicals [13,14]. Several reviews on catalytic and non-catalytic WAO [4,5,[15][16][17][18][19], supercritical water oxidation (SCWO) [7,8,[20][21][22] and advanced oxidation processes (AOP) [23][24][25] are now available in literature.…”

Decolourization of anthraquinone reactive dye by electrochemical reduction on reticulated glassy carbon electrode

“…5 Over the past few years, alternative methods 6-10 for dye treatment have been investigated, including chemical oxidation with reagents such as: ozone, hydrogen peroxide, ozone/UV, hydrogen peroxide/UV and Fenton's reagent [hydrogen peroxide + Fe (II)]. The application of electrochemical oxidation with or without UV light as method for dye degradation have also been investigated, [11][12][13][14][15] but no mechanisms of the reduction were discussed. [16][17][18][19] Most of the electrochemical studies involving reduction of reactive dyes are based on mercury electrode [16][17][18][19] and the decolorization and mineralization by electrochemical treatment are less studied.…”

Degradation of Tannic Acid Using TiO2 Nanotubes as Electrocatalyst

“…In general, the pH of the electrolyte mostly affects the indirect mediated oxidation. In alkaline condition, the evolution of oxygen is comparatively high and thus prevents the diffusion of pollutant molecule to the electrode surface [30]. Further, inactive hydroperoxide (HO 2 − ) anion which acts as scavenger for OH * is formed in alkaline pH [31]:…”