Hypochlorite production on Ru‐Sn binary oxide electrode and its application in treatment of dye wastewater

Abstract

Ruthenium-tin binary oxides [(Ru+Sn)02] were coated on titanium substrates by thermal decomposition. The surface morphologies and elemental analyses of these electrodes were examined by means of scanning electron microscopy. The electrochemical behaviours were characterized by cyclic voltammetry and linear-scan voltammetry (LSV) methods. The effects of electrolysis condition for the current efficiency (CE) of hypochlorite production on binary (Ru+Sn)02 electrodes and the treatment of a high salt-containing dye wastewater using this hypochlorite were also investigated. The highest CE for hypochlorite production exists on an RS3 (40 to 80 mol% Sn in coating solution) electrode. The major factors influencing CE for hypochlorite production are the electrolyte flow rate, current density, and chloride (Cl-) concentration. Major factors affecting energy yield are current density, CI-concentration, and electrode distance. For low current density (300 mA.cm-2), high CI-concentration (1 mol .L-l), and 0.45 cm electrode separation, a high specific energy is obtained. The RS3 electrode exhibits the best removal of organics and chromophor groups in the dye wastewater. On this electrode, better removal of organics and chromophor groups is obtained at 300 mA.crnp2. The colour of blackred dye wastewater becomes light yellow when a charge of 792 A.min was passed, while the chemical oxygen demand (COD) of this wastewater is decreased from 10500 mgL-I to 1250 mg.L-l.Des oxydes binaires de ruthenium-etain [(Ru+Sn)02] ont ete enduits sur des substrats de titane par decomposition thermique. Les morphologies de surface et les analyses elementaires de ces electrodes ont ete examinees par microscopie electronique a balayage. Les comportements electrochimiques ont ete caracterises par des methodes de voltametrie cyclique (CV) et voltametrie a balayage lineaire (LSV). On a egalement etudie les effets des conditions de I'electrolyse sur le rendement de courant (CE) lors de la production d'hypochlorite sur des electrodes binaires (Ru+Sn)02 et le traitement d'une eau usee de teinture a haute teneur en sel a I'aide de cette hypochlorite. Le meilleur CE pour la production d'hypochlorite est celle de I'electrode RS3 (40 a 80% molaire de Sn dans la solution d'enduit). Les principaux facteurs influenqant le CE pour la production d'hypochlorite sont le debit de I'electrolyte, la densite de courant et la concentration de chlorure (Cl-). Les principaux facteurs qui influent sur le rendement energetique sont la densite de courant, la concentration de CI-et la distance entre les electrodes. Pour une faible densite de courant (300 mA.cm-% une forte concentration de CI-(I mo1.L-I) et une separation des electrodes de 0,45 cm, on obtient une energie specifique elevee. L'electrode RS3 montre le meilleur retrait des groupes organiques et chromophores dans I'eau usee de teinture. Sur cette electrode, le meilleur retrait des groupes organiques et chromophores est obtenu a 300 mA.cm-2. La couleur rouge-noire de I'eau usee de teinture devient jaune plle lorsqu'u...

Oxidation of Levafix CA reactive azo-dyes in industrial wastewater of textile dyeing by electro-generated Fenton's reagent

“…This behavior may be due to the increase of conductivity of the medium [38] and cannot be attributed to participation of active chlorine (in the form of Cl 2 , HOCl, or ClO − ) that may be generated by oxidation of Cl − ions at the anode surface [39][40][41]. This is because Cl − ions remain stable in solution when Pt is used as anode [42][43][44] and formation of HOCl, or ClO − is favored only in neutral or alkaline media [45][46][47].…”

Degradation of microcystins in aqueous solution with in situ electrogenerated active chlorine

“…In the case without Cl À , the degradation of MCs is derived from direct oxidation of anode. But in the presence of Cl À , the concentration of C1 À became the key factor to influence the MCs removal, because of its effect on the production of active chlorine (Czarnetzki and Janssen, 1992;Yang et al, 2000). Therefore, the oxidation of active chlorine in bulk with Cl À played a more important role in the removal of MCs than direct one.…”

“…In recent years, mainly because of the ease of control and the increased efficiencies, there has been great interest in the development of practical electrochemical methods such as anodic oxidation and indirect electrooxidation (Yang et al, 2000). It has been demonstrated that the addition of chloride ions in the electrolyte caused an increase in removal efficiency, and the complete degradation of pollutants can be achieved due to the participation of active chlorine, in the form of chlorine, hypochlorous acid and hypochlorite.…”

Electrochemical degradation of Amaranth aqueous solution on ACF

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