The preparation of PbO2 coatings on reticulated vitreous carbon for the electro-oxidation of organic pollutants

• Published in: Electrochimica acta Vol. 56; no. 14; pp. 5158 - 5165
• Main Authors: Recio, F.J., Herrasti, P., Sirés, I., Kulak, A.N., Bavykin, D.V., Ponce-de-León, C., Walsh, F.C.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 30.05.2011; Elsevier
• Subjects: Applied sciences; Chemistry; Electrochemical oxidation; Electrochemistry; Electrodeposition; Electrodes: preparations and properties; Exact sciences and technology; General and physical chemistry; General purification processes; Kinetics and mechanism of reactions; Lead dioxide; Methanesulfonic acid; Other electrodes; Pollution; Reticulated vitreous carbon; Wastewaters; Water treatment and pollution; Electrodeposition; Methanesulfonic acid; Lead dioxide; Reticulated vitreous carbon; Electrochemical oxidation; Anode; Electrode material; Surface structure; Electrocatalysis; Mineralization; Azo dye; Oxidation; Methyl orange; Electrochemical reaction; Organic compounds; Modified material; Scanning electron microscopy; Lead IV Oxides; Nanostructure; Carbon; X ray diffraction; Pollutant; Morphology; Preparation; Kinetics; Aqueous solution; Waste water purification; Glassy state
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2011.03.054

► PbO2-based coatings and novel composites on reticulated vitreous carbon (RVC). ► No previous studies reporting the use of RVC/PbO2 to degrade organic pollutants. ► The resulting 3D, nanostructured β-PbO2 anodes exhibit thick, adherent coatings. ► Co-deposition of PbO2 with hydrothermally synthesized TiNT yields the best results. ► RVC/PbO2/TiNT composite coatings are chemically and mechanically stable. The preparation of PbO2 coatings on reticulated vitreous carbon (RVC) has been carried out at constant current from electrolytic baths containing aqueous Pb(II) and methanesulfonic acid (MSA, CH3SO3H). The morphological and structural analysis of the RVC/PbO2 deposits carried out by scanning electron microscopy (SEM) and X-ray diffraction revealed that a thick (100μm), homogeneous, nanostructured β-PbO2 film can be successfully formed. As a result, three-dimensional β-PbO2 structures were obtained, being particularly interesting for their use as anodes in wastewater treatment. The high oxidation ability of these anodes has been verified by the electro-oxidation of Methyl Orange aqueous solutions. Quick decolourisation was achieved, with total colour removal in less than 60min at 600mA due to the production of large amounts of reactive OH radicals from the oxidation of water at high anodic potentials. The progressive mineralisation of the solutions was also ascertained from the total organic carbon (TOC) removal, which was much quicker at a higher applied current. All the coated RVC electrodes exhibited excellent long-term stability and remained unaltered after prolonged electrolyses. In addition, novel PbO2 composite coatings were prepared in the presence of hydrothermally synthesized titanate nanotubes (TiNT). The SEM images showed the presence of TiNT agglomerates along the PbO2 surface, which led to higher anodic current in the cyclic voltammetries carried out with Methyl Orange solutions. It is suggested that TiNT favour the adsorption of the organic molecules, facilitating the contact with the OH radicals and thus accelerating the electro-oxidation process. This was confirmed by the faster TOC removal compared to that yielded by the RVC/PbO2, being 45% instead of 24% at 120min.