Study of the Discoloration Rate of Rhodamine B as a Function of the Operating Parameters at Pt and BDD Electrodes

Abstract

The chemical reaction of rhodamine B by electro-generated species using Pt and BDD electrodes was performed. The product(s) of this chemical reaction are related to the supporting electrolyte and electrolysis time. The rate of discoloration is affected by the current density, initial pH, temperature, and the nature of the supporting electrolyte. However, the initial dye concentration and the ionic strength did not show any significant effect on both electrodes. Discoloration of the dye and mineralization were not observed in presence of sulfate and nitrate with the Pt electrode, but occurred slowly with the BDD electrode. In the presence of KCl and KBr, the discoloration was very fast with both electrodes, and was accompanied with partial degradation. In the presence of KCl, the colorless rhodamine B solution turned rose after several hours of being set at rest.

Effect of Operating Parameters on Electrochemical Degradation of Alizarin Red S on Pt and BDD Electrodes

“…The increase in the degradation rate is related to the increase in the production rate of chlorine species. Similar results are obtained with other compounds [14,15,16,29].…”

“…The effect of this parameter is negligible, may be because the dye and the oxidants (HOCl, Cl 2 ) are both neutral at the pH of the experiment (pH 0 : 1.7). Similar results are obtained with the xanthene dyes [15,16].…”

“…The reason is that more amount of chlorine/hypochlorite will be generated while increasing the chloride concentration due to increased mass transport of chloride ions to the anode surface [10]. This result confirms the discoloration and the degradation of the organic compounds via the electro-generated halide species [15,16].…”

“…SO [12,13,15,16]. BDD electrode possesses interesting properties such as an inert surface with low adsorption properties, considerable corrosion stability and an extremely wide potential window in aqueous medium.…”

“…The efficiency of the electrochemical oxidation of dyes is a function of the electrode and the supporting electrolyte [11][12][13][14][15][16][17][18]. Many electrode materials have been tested: noble metals, different forms of carbon, BDD and metal oxides [9].…”