Effect of Specific Active Chlorine Species and Temperature on the Electrochemical Degradation of the Reactive Blue 19 Dye Using a Boron-Doped Diamond or DSA Anode in a Flow Reactor

Electrochemical degradation of the herbicide picloram using a filter-press flow reactor with a boron-doped diamond or β-PbO 2 anode

“…Electrochemical methods were used to degrade different types of organic compounds in aqueous solutions/effluents [21], including dyes [22][23][24][25][26][27][28][29][30], plasticizers [31,32], pharmaceuticals [33][34][35][36], as well as pesticides [4,[37][38][39][40][41]. These methods are based on the direct and/or indirect oxidation of the organic molecules (and their 4 degradation intermediates), which may lead to total mineralization [21].…”

“…The BDD and β-PbO2 anodes have been extensively investigated in the electrooxidation of solutions/effluents containing organics due to their excellent chemical stability and high overpotential for the oxygen evolution reaction, which favors • OH electrogeneration [23][24][25]29,31]. Despite the fact that • OH is a potent oxidant, other types of oxidants may be electrolytically generated if certain chemical species are present in solution, such as Cl -or SO41 -ions, when their oxidation leads to the formation of active chlorine (Cl2, HOCl, or OCl -, whose individual concentrations are dependent on the concentration of Cl -and the solution pH, temperature, and ionic strength [44]) or persulfate ions (S2O8 2-) [26,45]; furthermore, hydrogen peroxide (H2O2) may be formed by the combination of hydroxyl radicals [43]. These oxidants, once formed, diffuse to the bulk of the solution; thus, they may decrease the organics oxidation dependence on mass transfer to the electrode surface and, hence, increase the process rate and efficiency.…”

“…For instance, Aquino et al[44] reported that the best conditions for COD abatement of a solution of the Direct Orange 29 dye containing Cl -ions in the supporting electrolyte (0.10 M Na2SO4) were neutral to alkaline solutions (for [NaCl] < 1.0 g L -1 and high temperatures), whereas those for TOC abatement were slightly acidic to alkaline solutions (for 1.2 g L -1 ≤ [NaCl] < 1.7 g L -1 ). On the other hand, Degaki et al[26] showed that the electrochemical decolorization of the Reactive Blue 19 dye is significantly enhanced by the presence in solution of electrogenerated active chlorine, especially at pH 1, when Cl2 is the predominant active-chlorine species. In the investigation here reported, the concentration of Cl -ions in the supporting electrolyte and the solution temperature were kept constant (25 mM and 25 °C, respectively) while the solution pH was varied (3, 6, and 10).…”

Electrochemical Oxidation of Reactive Black 5 and Blue 19 Dyes Using a Non Commercial Boron-Doped Diamond Electrode

“…Esse comportamento foi justificado devido à influência positiva que o aumento da temperatura causa no transporte de massa. Todavia, Degaki et al 51 e Petrucci e Montanaro 52 concluíram que o aumento da temperatura influenciou positivamente a remoção do corante via oxidação também utilizando filmes de DDB. Vale destacar que foram utilizados eletrodos de DDB comerciais, sendo que a dopagem foi mencionada apenas no trabalho de Degaki et al, 51 entre 2.000 e 4.500 ppm relação B/C.…”

Electrochemical Degradation of Reactive Blue 19 Dye by Combining Boron‐Doped Diamond and Reticulated Vitreous Carbon Electrodes

“…At these conditions, 100 % of TOC was removed after 120 min of electrolysis at 600 mA cm −2 current density. On the other hand Degaki et al . also reported a low TOC removal (65 %) after oxidation of 500 mg dm −3 of RB‐19 dye in 0.1 mol dm −3 of Na 2 SO 4 even in presence of 34×10 −3 mol dm −3 of NaCl when a charge of around 8 A h dm −3 was applied to BDD/Nb (geometric area of 11 cm 2 ) and AISI‐304 stainless steel foils cathodes fitted in a one‐compartment filter‐press reactor.…”