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In this work, the efficiency of electrochemical oxidation (EO) was investigated for removing a dye mixture containing Novacron Yellow (NY) and Remazol Red (RR) in aqueous solutions using platinum supported on titanium (Ti/Pt) as anode. Different current densities (20, 40 and 60 mA cm(-2)) and temperatures (25, 40 and 60 °C) were studied during electrochemical treatment. After that, the EO of each of these dyes was separately investigated. The EO of each of these dyes was performed, varying only the current density and keeping the same temperature (25 °C). The elimination of colour was monitored by UV-visible spectroscopy, and the degradation of organic compounds was analysed by means of chemical oxygen demand (COD). Data obtained from the analysis of the dye mixture showed that the EO process was effective in colour removal, in which more than 90% was removed. In the case of COD removal, the application of a current density greater than 40 mA cm(-2) favoured the oxygen evolution reaction, and no complete oxidation was achieved. Regarding the analysis of individual anodic oxidation dyes, it was appreciated that the data for the NY were very close to the results obtained for the oxidation of the dye mixture while the RR dye achieved higher colour removal but lower COD elimination. These results suggest that the oxidation efficiency is dependent on the nature of the organic molecule, and it was confirmed by the intermediates identified.

In the present paper, differential pulse voltammetry (DPV) techniques has been studied for monitoring of the concentration of oxalic acid (OA) during its electrochemical oxidation (EO) in acidic media at BDD anode applying a current of 60 mA cm 2 . Glassy carbon has been used for DPV measurements using two analytical procedures: calibration curves (DPVCC) and standard addition method (DPVSAM). DPV analyses have compared with classic titration method and HPLC achieving a good fit, confidence intervals and limits

The electrochemical oxidation (EO) of oxalic acid (OA) has been studied, in acidic media at Ti/PbO2, highly boron-doped diamond (BDD), Pt and graphite electrodes by applying 60 mAcm−2 of current density. Generally, EO is monitored by chromatography techniques; but the aim of this work is to show the applicability of electroanalysis for detection of OA concentration during its oxidation; by differential pulse voltammetry (DPV) using two different analytical procedures (by analytical curve and by successive addition standard). The results obtained by DPV analysis showed that OA was oxidized at several substrates to CO2 with different results, showing that the performances of the process dramatically depend on the anodic material. Higher removal efficiencies were obtained at Ti/PbO2, graphite and BDD anodes. Finally, DPV analyses were compared with classic titration method achieving a good fit, confidence intervals and limits. The results are described and discussed in the light of the existing literature.

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