Degradation of a Textile Dye C. I. Direct Red 80 by Electrochemical Processes

Abstract

The electrochemical removal of the textile dye C. I. Direct Red 80 (DR80) was carried out using three different materials as anodes: iron, polypyrrole (PPy) and boron doped diamond (BDD). Iron electrodes are consumed during the electrolysis, and promote flocculation/coagulation of the dye. Polypyrrole, a conducting polymer, was prepared by chemical/electrochemical precipitation over a cotton cloth; it enables the precipitation of the dissolved dye through a conversion reaction in a less soluble compound. Boron doped diamond electrode was used to achieve the complete mineralization of the dye. Bulk electrolysis were studied using Na 2 SO 4 as electrolyte. In the case of the PPy electrode, NH 4 NO 3 was also used as electrolyte. The variation of the dye concentration was followed by UV-visible absorbance measurements and chemical oxygen demand (COD) tests were also performed, to compare the rates of colour and COD removal in each case. From the COD measurements over the time of electrolysis, using the BDD anode, a mass transfer coefficient for the DR80 molecule was determined. The obtained results show an almost complete colour removal for all the electrodes tested and a COD removal between 50 and 90 %, being the best results obtained with the BDD electrode.

Application of low-cost adsorbents for dye removal – A review

“…Several anode materials, like iron, conducting polymer a boron doped diamond electrode etc., with different experimental conditions, have been used successfully in the electro-degradation of dyes (Dogan and Turkdemir, 2005;Faouzi et al, 2007;Oliveira et al, 2007a). A colour removal (Lopes et al, 2004) of 83-100% was observed for Direct Red 80 using three different electrodes: iron, polypyrrole doped with chromium and boron doped diamond electrode. This technique is effective in decolourisation of soluble and insoluble dyes with reduction of COD.…”

Electrochemical degradation of Reactive Red 120 using DSA and BDD anodes

“…Typical examples of widely used anodes include Fe [27], steel [28,29], Al [30], Dimensionally Stable Anodes (DSA) composed of mixtures of Ti, Ir, Ru, Sn, Pb and/or Sb oxides [31][32][33], Pt [29,34] or Tisupported Pt [35], granular activated carbon [14], activated carbon fiber (ACF) [15], glassy carbon [16], graphite [17], polypyrrole [18], perovskite-like BaPb 0.9 Sb 0.1 O 3 [19] and BDD deposited mainly on Si [20], Ti [21] or Nb [7] substrates. These electrodes could be used either for direct (occurring at the surface of the anode) or for indirect oxidation processes such as the homogeneous reaction of organic pollutants with strong oxidants (like active chlorine [36], or hydroxyl radicals via Fenton's reaction [37]).…”

Chemical, electrical and electrochemical characterization of hybrid organic/inorganic polypyrrole/PW12O403− coating deposited on polyester fabrics

“…The employment of polypyrrole coated textiles in the electrochemical removal of the textile dye C. I. Direct Red 80 has been also reported [26]. Polyaniline/MnO 2 catalyst and H 2 O 2 as an oxidant have been employed in the degradation of organic dyes such as Direct Red 81, Indigo Carmine and Acid Blue 92 [27,28].…”