Role of SiOx interlayer in the electrochemical degradation of Amaranth dye using SS/PbO2 anodes

A novel SS (Stainless steel)/SiOx/PbO2 anode for dye removal in water electrolysis was studied. SiOx interlayer was deposited by plasma enhanced chemical vapor deposition (PECVD) in plasma fed with argon, oxygen and tetraethoxysilane (TEOS) in different ratios. Lead oxide was deposited by pulsed electrodeposition. Well-adherent and homogeneous SiOx film, characterized by high hydrophobicity, were deposited in oxygen rich plasma onto the SS substrate as confirmed by the morphological characterization performed by means of Field Emission Scanning Electron Microscopy (FESEM). The composition of PbO2 layer was investigated by X-ray diffractometry (XRD) and evidenced that β-PbO2 crystallites nucleation was promoted by the SiOx interlayer. Additionally, Electrochemical Impedance Spectroscopy (EIS) measurements were performed for assessing the electrochemical behaviour of the SS/SiOx/PbO2 anodes. Results confirmed that the increase in the presence of the β-PbO2 form, increases the conductivity of the PbO2 film. Finally, the anode, with SiOx interlayer deposited in oxygen rich plasma, showed the best efficiency in removing the azoic dye from aqueous solution in terms of COD and color remova

Effect of coating method on the structure and properties of a novel PbO2 anode for electrochemical oxidation of Amaranth dye

This study deals with the electrochemical degradation of Amaranth in aqueous solution by means of stainless steel (SS) electrodes coated with a SiOx interlayer deposited by Plasma Enhanced Chemical Vapour Deposition and a modified PbO2 top layer deposited by continuous galvanostatic electrodeposition. The morphological characterization of the PbO2 top-layer performed by Field Emission Scanning Electron Microscope put in evidence that the SiOx, interlayer allows obtaining a more integrated PbO2/SS electrode with a very homogeneous PbO2 film. The composition of the lead oxide layer was investigated by X-ray Diffractometry, showing that the b-PbO2/a-PbO2 ratio in the top layer deposited on the SiOx film was four times higher respect to the one deposited directly on the stainless steel surface. In addition, the electrochemical behaviour of SS/SiOx/PbO2 interfaces was studied by electrochemical impedance spectroscopy (EIS). The EIS results showed that the presence of SiOx favors electron transfer within the oxide layer which improves electro-oxidation capability. Moreover, bulk electrolysis showed that over 100% colour removal and 84% COD removal, using SS/SiOx/PbO2 at acidic pH were reached after 300min. High Performance Liquid Chromatography analysis was used for the quantitative determinations of initial Amaranth dye molecule removal and to evaluate its specific degradation rate. In order to evaluate the phototoxicity of treated solution with different by-products, different tests of germination were performed and proved that the electrochemical treatment with modified PbO2 could be as an efficient technology for reducing hazardous wastewater toxicity and able to produce water available for reuse