Electrochemical treatment of wastewaters containing 4-nitrocathecol using boron-doped diamond anodesA paper submitted to the Journal of Environmental Engineering and Science.

2009 ◽  
Vol 36 (4) ◽  
pp. 683-689
Author(s):  
Nasr Bensalah ◽  
Mohamed F. Ahmadi ◽  
Abdelatif Gadri
Keyword(s):  
Electrochemical Oxidation ◽  
Carboxylic Acids ◽  
Aromatic Ring ◽  
Supporting Electrolyte ◽  
Electrochemical Treatment ◽  
Boron Doped Diamond ◽  
Potential Region ◽  
Polymeric Product ◽  
Boron Doped ◽  
Mineral Product

The electrochemical oxidation of aqueous wastes polluted with 4-nitrocathecol has been studied on boron-doped diamond electrodes in an acidic medium. The voltammetric results showed that 4-nitrocathecol is oxidized in the potential region where the supporting electrolyte is stable. Galvanostatic electrolysis study showed that the oxidation of these wastes in a single-compartment electrochemical flow cell with boron-doped diamond anodes results in the complete mineralization of the organics. Cathecol, benzoquinone, 4-aminocathecol, maleic and oxalic acids have been detected as soluble organics, polymeric product as solid product at the cathode surface and NO3– as mineral product during the electrolysis of 4-nitrocathecol. The electrochemical oxidation of 4-nitrocathecol consists of a sequence of steps: release of NO2 and (or) hydroxylation of the aromatic ring; formation of quinonic compounds; oxidative opening of aromatic ring to form carboxylic acids; and oxidation of carboxylic acids to carbon dioxide. Both direct and mediated oxidation processes are involved in these stages.

scholarly journals Electrochemical Treatment of synthetic and Actual Dyeing Wastewaters Using BDD Anodes

2010 ◽  
Vol 3 ◽  
pp. ASWR.S3639 ◽  
Author(s):  
Nasr Bensalah ◽  
Ahmed Abdel-Wahab
Keyword(s):  
Supporting Electrolyte ◽  
Great Influence ◽  
Electrochemical Treatment ◽  
Electrochemical Process ◽  
Operating Conditions ◽  
Anode Surface ◽  
Boron Doped Diamond ◽  
Potential Region ◽  
Toc Removal ◽  
Boron Doped

In this work, the treatment of synthetic wastewaters containing methylene blue (MB) and rhodamine B (RB) and actual textile wastewaters (ATW) using boron doped diamond (BDD) anodic oxidation was investigated. Voltammetric study has shown that both MB and RB can be oxidized directly at the anode surface in the potential region where the electrolyte salt is stable. Galvanostatic electrolyses of synthetic and actual industrial wastewaters have led to total abatement of COD and TOC at different operating conditions (electrolyte salt and initial pollutant concentration and current density) and the efficiency of the electrochemical process was governed only by mass-transfer limitations. The nature of the supporting electrolyte has a great influence on the rate and the efficiency of the electrochemical oxidation of dyes. The treatment in the presence of NaCl appears to be more efficient in the COD removal, while in the presence of Na2SO4 improves the TOC removal. From the experimental results it seems that the primary mechanisms in the oxidation of dyes are the mediated electro-oxidation by hydroxyl radicals and other oxidants electro-generated from supporting electrolyte oxidation.

Anodic Oxidation of Aqueous Wastes Containing Hydroquinone on BDD Electrode

2015 ◽  
Vol 18 (1) ◽  
Author(s):  
Hassen Trabelsi ◽  
Nasr Bensalah ◽  
Abdellatif Gadri
Keyword(s):  
High Efficiency ◽  
Supporting Electrolyte ◽  
Electrochemical Process ◽  
Applied Current ◽  
Boron Doped Diamond ◽  
Potential Region ◽  
Boron Doped ◽  
Electro Oxidation ◽  
Discontinuous Mode ◽  
Hplc Analyses

AbstractThe electrochemical oxidation of 1,4 dihydroxybenzene, was studied by galvanostatic electrolysis using boron-doped diamond (BDD) as anode. The efficiency of the electrochemical process was found to depend mainly on the pollutant concentration present in the waste and on the applied current density. The voltammetric results showed that hydroquinone oxidation takes place in the same potential region as that of phenol where the supporting electrolyte is stable. Synthetic wastewaters containing hydroquinone have been treated in a bench-scale electrolysis plant. This plant operates in a discontinuous mode by recirculating the waste continuously through a single-chamber electrochemical flow cell. The complete mineralization of hydroquinone and the electro-generated pollutants is obtained in the electrolytic device. HPLC analyses show the formation of carboxylic acids as the main intermediates. The high efficiency of this technology can be explained in terms of the direct electro-oxidation at the BDD surface and the oxidation carried out by hydroxyl radicals and other electro-generated oxidants.

Treatment of ink effluents from flexographic printing by lime precipitation and boron-doped diamond (BDD) electrochemical oxidation

2009 ◽  
Vol 60 (10) ◽  
pp. 2477-2483 ◽  
Author(s):  
Evan Diamadopoulos ◽  
Helen Barndõk ◽  
Nikolaos P. Xekoukoulotakis ◽  
Dionissios Mantzavinos
Keyword(s):  
Electrochemical Oxidation ◽  
Supporting Electrolyte ◽  
Cod Removal ◽  
Effluent Treatment ◽  
Initial Value ◽  
Boron Doped Diamond ◽  
Treatment Performance ◽  
Boron Doped ◽  
Gravity Settling ◽  
Flexographic Printing

Effluent treatment from flexographic printing was investigated by precipitation/coagulation and electrochemical oxidation over boron-doped diamond electrodes. Precipitation with 3 g/L of lime led to complete removal of effluent turbidity (initial value of about 410 NTU) but only about 20% chemical oxygen demand (COD) decrease (initial value of about 1,900 mg/L). Higher lime dosages (up to 15 g/L) had no effect on separation. On the other hand, coagulation with alum in the range 0.05–1 mM failed to enhance the extent of solids separation achieved by gravity settling alone (i.e. about 60%). Preliminary electrochemical oxidation experiments in the presence of sulphuric acid as supporting electrolyte showed that treatment performance (in terms of COD removal and decrease in sample absorbance at 300 nm) increased with increasing applied current. The latter was more efficiently utilized at shorter treatment times and lower currents with efficiency reaching 30%. Following lime precipitation, the effluent was electrochemically oxidized at alkaline conditions for 360 min yielding 64% absorbance reduction and 50% COD removal (this corresponds to 60% overall COD removal for the combined process). The rather low electrochemical treatment performance may be attributed to limestone deposition and fouling of electrodes and other electrochemical reactor components as evidenced by the gradual drop in conductivity/current throughout the operation.

Electrochemical study of carboxylic acids with Nb-supported boron doped diamond anode. Part 2: Electrochemical oxidation associated to DFT calculations

2017 ◽  
Vol 794 ◽  
pp. 93-102 ◽  
Author(s):  
Amison Rick Lopes da Silva ◽  
Jorge Leandro Aquino de Queiroz ◽  
Dayanne Chianca de Moura ◽  
Djalma Ribeiro da Silva ◽  
Carlos A. Martínez-Huitle
Keyword(s):  
Dft Calculations ◽  
Electrochemical Oxidation ◽  
Carboxylic Acids ◽  
Electrochemical Study ◽  
Boron Doped Diamond ◽  
Boron Doped
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