Electrochemical Oxidation of Acid Violet 7 Dye by Using Si/BDD and Nb/BDD Electrodes

Abstract

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.

In-house vs. commercial boron-doped diamond electrodes for electrochemical degradation of water pollutants: A critical review

“…Polished silicon wafers are by far the most applied substrate material, being identified in more than 36% of the published articles (Supplementary Figure S1), especially p-doped Si commercial wafers. Their characteristic low electrochemical activity and ability to form stable and compact oxide films help prevent film delamination (Brito et al, 2018). However, Si substrates still have many limitations for large-scale applications since they are not suitable in aggressive water treatment environments, mainly due to their relatively low conductivity and brittleness (Yu et al, 2014).…”

“…However, the electrodes had different geometries (consequently, different specific areas), boron doping levels, and different film thicknesses, limiting comparisons between the different metallic substrates. Si/BDD and Nb/BDD electrodes have been compared in different studies for the electrooxidation of acid violet 7 dye (Brito et al, 2018) andnorfloxacin (da Silva et al, 2018). In both cases, the Si/BDD electrode showed higher removal rates with lower associated energy consumption.…”

Unprecedented formation of reactive BrO– ions and their role as mediators for organic compounds degradation: The fate of bromide ions released during the anodic oxidation of Bromophenol blue dye

“…All electrolyzes were performed in a single chamber circular disc parallel plate flow reactor (Figure 2). [40,41] The EO system consisted of a reservoir which stores the water matrix, thermometer, electrochemical cell and the peristatic pump to recirculate the solution through the flow reactor (Figure 2a). The flow cell was made of 1.7 cm thick circular polyvinyl chloride sandwiching between the electrode supports to form a single chamber cell with an effective volume of 110 cm 3 (Figure 2b).…”

Coupling of Anodic Oxidation and Soil Remediation Processes: A Review

“…AOPs based on hydroxyl radical productions ( • OH) such as ozonation, photocatalysis, Fenton oxidation, and electrochemical AOPs have been recently investigated for treating SW effluents with the best removal efficiency observed with electrochemical AOPs [2,3,12,[15][16][17]. Among the electrochemical AOPs, electrooxidation otherwise known as anodic oxidation (AO), has a distinguished advantage in that it requires very limited or no chemical for the generation of strong oxidant (reactive species) needed for oxidation of the organic pollutants [18][19][20][21]. In AO, reactive oxygen species (ROS) or reactive chloride species (RCS) are electrogenerated at the anode region via water/chlorine oxidation [22][23][24][25].…”