Lead dioxide

Abstract: Lead dioxide coatings on inert substrates such as titanium and carbon now offer new opportunities for a material known for 150 years. It is now recognised that electrodeposition allows the preparation of stable coatings with different phase structures and a wide range of surface morphologies. In addition, substantial modification to the physical properties and catalytic activities of the coatings are possible through doping and the fabrication of nanostructured deposits or composites. In addition to applications as a cheap anode material in electrochemical technology, lead dioxide coatings provide unique possibilities for probing the dependence of catalytic activity on layer composition and structure (critical review, 256 references).

Abstract: Recent studies have shown that the lack of ideal anodes with both good activity and stability is still one of the critical problems in electrochemical oxidation for organic wastewater treatment. The electrochemical properties, the activity and stability for anodic oxidation of various phenolic compounds, and the degradation mechanism on a novel β-PbO2 electrode modified with fluorine resin were investigated. The anode life after modification was greatly improved to be more than 10 yr in common electrochemical current conditions. Such an anode was effective for partial degradation of phenolic compounds, but selective because reactive activities were varied with different substituents. Characterized by SEM and XRD, the crystal form of the anode was verified to be mainly β-PbO2, and it hardly changed when used for p-nitrophenol degradation for around 320 h although there existed slow electrode corrosion. The active species generated during anodic oxidation were determined to be mainly hydroxyl radical and li...

Abstract: The recovery of copper, lead and tin from scrap printed circuit boards (PCBs) has been achieved using a combination of leaching, electrochemical ion exchange and electrodeposition. A simple aqueous nitric acid stripping solution, with the concentration range of 1–6 mol dm−3, has demonstrated the potential for selective extraction of copper and lead from the PCBs. Precipitation of tin as H2SnO3 (metastannic acid) occurred at acid concentrations above 4 mol dm−3. Preliminary galvanostatic electrolysis from simulated leaching solutions has investigated the feasibility of electrodeposition of copper and lead at different concentrations of HNO3. Cathodic lead deposition, particularly at high electrolyte conditions, resulted in poor current efficiency. This was mainly due to dentritic metal formation and subsequent re-dissolution. An alternative method investigated for recovering the metal values was the simultaneous electrodeposition of copper at the cathode and lead dioxide at the anode. Electrohydrolysis for acid and base regeneration from the spent nitric acid electrolyte has also been investigated. © 2002 Society of Chemical Industry

Abstract: The electrocatalytic properties of Ti–Ru–Sn ternary oxide, platinum, lead dioxide and boron-doped diamond anodes for the oxidation of methyl red have been compared by potentiodynamic measurements and bulk electrolysis. The results of the cyclic voltammetries have shown that in the potential region of supporting electrolyte stability polymeric materials, which result in electrode deactivation, are formed on the electrode surfaces. While Ti–Ru–Sn ternary oxide and platinum cannot restore their initial activity by polarization, lead dioxide and boron-doped diamond anodes can be reactivated by electrolysis in the potential region of electrolyte decomposition due to the electrogeneration of hydroxyl radicals. The bulk electrolysis showed that the complete COD and colour removal were only achieved using lead dioxide and boron-doped diamond while Ti–Ru–Sn ternary oxide and platinum only permitted a partial oxidation of methyl red.