Fabrication and application of Nafion®-modified boron doped diamond electrode as sensor for detecting caffeine

The surface of boron-doped diamond (BDD) electrodes has been modified by Nafion®. The polymer film was applied onto the BDD electrode surface by solvent evaporation. Nafion®-BDD electrode was used as a sensor for caffeine detection in e.g. cola beverage samples. In cyclic voltammetric measurements, favorable ionic interaction between the Nafion® film and caffeine enhances the current response, and thus the sensitivity, compared to that at the bare electrode. The modified electrode exhibits a stable and sensitive response to caffeine and may represent a new analytical tool, offering a significant improvement over other electroanalytical methods (e.g.: Nafion®-modified glassy carbon electrode) and the accepted method for caffeine analysis (HPLC-MS). The analysis of residuals from the linear regression proved that a linear response exists from 2.0×10-7 to 1.2×10-5 M, obtaining a limit of detection of about 1.0×10-7 M. The findings presented in this short communication are described and discussed in the light of the existing literature

Los autos y la electroquímica

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Anodic oxidation of Tartaric acid at different electrode materials

Aim of the present communication is to show experimental results, and related conclusions, on the electrochemical oxidation (EO) of tartaric acid (TA), which has been oxidized at Ti/PbO2, Ti/Pt, Pt and HBDD electrodes at different current densities in acidic media. TA complete mineralization has been achieved only at HBDD and Ti/PbO2, being higher the faradaic efficiency at the latter electrode. At Pt electrode, the electroxidation was found to be extremely slow, in acidic conditions. The experimental evidence has shown that the main factor is the interaction of the organic substrate and hydroxyl radicals with the electrode surface, during TA oxidation. In the case of the EO of oxalic acid (OA) in acidic media that was previously studied, better results were obtained at the Pt electrode, supporting the idea that the interaction of organic substrate with the electrode surface, was the main determining parameter and based on the results here reported, this idea was confirmed for TA, more complex compound than OA

Scale-up of electrochemical oxidation system for treatment of produced water generated by Brazilian petrochemical industry

Scale-up of anodic oxidation system is critical to the practical application of electrochemical treatment in biorefractory organic wastewater treatment. In this study, the scale-up of electrochemical flow system was investigated by treating petrochemical wastewater using platinized titanium (Ti/Pt) and boron-doped diamond (BDD) anodes. It was demonstrated that flow cell was successfully scaled-up because when it was compared with batch mode (Rocha et al. 2012b), higher performances on organic matter removal were achieved. Under the suitable operating conditions and better anode material, the chemical oxygen demand (COD) of petrochemical wastewater was reduced from 2,746 to 200 mg L−1 within 5 h with an energy consumption of only 56.2 kWh m−3 in the scaled-up BDD anode system. These results demonstrate that anode flow system is very promising in practical bio-refractory organic wastewater treatment