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Aim of this work is to discuss the electrochemical colour removal process of a textile dye (Yellow Novacron (YN)) dissolved in synthetic wastewaters, analyzing the influence of NaCl. Experiments were carried out at boron-doped diamond (BDD) and Platinum supported in Titanium (Ti/Pt). The process is significantly accelerated by the presence of a halogen salt in solution; interestingly, the mediated process does not depend on applied current density; but it depends on NaCl concentration. Finally, the parameters of removal efficiency and energy consumption for the electrochemical decolourisation process were estimated.

The electrochemical performance of thin film boron-doped diamond (BDD) electrodes deposited on either single crystal p-type Si (Si/BDD) or Nb (Nb/BDD) substrates have been investigated for the electrooxidation of azo-dye Acid Violet 7 (AV7). Both electrodes were characterized by linear voltammetry and the production of hydroxyl radicals ( • OH) at their surfaces was assessed by spin trap experiment using N,N-dimethyl-p-nitrosoaniline (RNO) as a spin trap molecule. Slightly higher O 2 evolution reaction (OER) potential was observed with Nb/BDD compared to Si/BDD in both 0.05 M Na 2 SO 4 and AV7 solutions. Enhanced bleaching of RNO was always observed when an increased current density was applied and a significant decay of the adsorption band of RNO was attained with Nb/BDD compared to Si/BDD electrode, indicating higher generation of • OH on its surface. Complete decolorization of 200 mg L -1 of AV7 was achieved with either electrodes at current density of 30 and 60 mA cm -2 in 120 min or less. Quite similar degradation efficiency was attained at both electrodes but Si/BDD showed better results than Nb/BDD. Nevertheless, lower energy requirements was achieved by Nb/BDD, demonstrating that it can be a suitable electrode for an efficient electrochemical oxidation process.

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In recent years, due to industrial modernization and agricultural mechanization, several environmental consequences have been observed, which make sustainable development difficult. Soil, as an important component of ecosystem and a key resource for the survival of human and animals, has been under constant contamination from different human activities. Contaminated soils and sites require remediation not only because of the hazardous threat it possess to the environment but also due to the shortage of fresh land for both agriculture and urbanization. Combined or coupled remediation technologies are one of the efficient processes for the treatment of contaminated soils. In these technologies, two or more soil remediation techniques are applied simultaneously or sequentially, in which one technique complements the other, making the treatment very efficient. Coupling anodic oxidation (AO) and soil remediation for the treatment of soil contaminated with organics has been studied via two configurations: (i) soil remediation, ex situ AO, where AO is used as a post-treatment stage for the treatment of effluents from soil remediation process and (ii) soil remediation, in situ AO, where both processes are applied simultaneously. The former is the most widely investigated configuration of the combined processes, while the latter is less common due to the greater diffusion dependency of AO as an electrode process. In this review, the concept of soil washing (SW)/soil flushing (SF) and electrokinetic as soil remediation techniques are briefly explained followed by a discussion of different configurations of combined AO and soil remediation.

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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.

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