No abstract

No abstract

The performance of a catalyzed H 2 O 2 electrogeneration process using a modified oxygen-fed graphite/PTFE electrode is reported. The organic redox catalyst chosen for incorporation into the graphitic mass was azobenzene. The yield of the hydrogen peroxide is related to the applied potential and to azobenzene concentration. Modification of the gas diffusion electrode with azobenzene improved hydrogen peroxide production, and the overpotential for oxygen reduction was shifted to less negative values compared to the performance of a non-catalyzed electrode, indicating that these modified electrodes have good electro-activity.

An electrochemical reactor for oxygen/ozone production was developed using perforated planar electrodes. An electroformed b-PbO 2 coating, deposited on a platinised titanium substrate, was employed as anode while the cathode was a platinised titanium substrate. The electrodes were pressed against a solid polymer electrolyte to minimise ohmic drop and avoid mixing of the gaseous products (H 2 and O 2 /O 3 ). Electrochemical ozone production (EOP) was investigated as function of current density, temperature and electrolyte composition. Electrochemical characterisation demonstrated ozone current efficiency, F EOP , ozone production rate (g h )1 ), m EOP , and grams of O 3 per total energy demand (g h )1 W )1 ), m EOP increase on decreasing electrolyte temperature and increasing current density. The best reactor performance for EOP was obtained with the base electrolyte (H 2 SO 4 3.0 mol dm )3 ) containing 0.03 mol dm )3 KPF 6 . Degradation of reactive dyes used in the textile industry (Reactive Yellow 143 and Reactive Blue 264) with electrochemically-generated ozone was investigated in alkaline medium as function of ozone load (mg h )1 ) and ozonation time. This investigation revealed ozonation presents very good efficiency for both solution decolouration and total organic carbon (TOC) removal.