How Dimensionally Stable Titanium Anodes are Used for Pharmaceutical Effluent Advanced Oxidation Processes

How Dimensionally Stable Titanium Anodes are Used for Pharmaceutical Effluent Advanced Oxidation Processes (AOPs)?
 
Pharmaceutical effluent is highly toxic to biological life and is usually characterized by the high BOD, COD, and COD: BOD ratio and has toxic components like cyanide. Advanced oxidation processes (AOPs) are an effective method for pharmaceutical effluent treatment, which rely on the generation of reactive hydroxyl radicals.  

Dimensionally stable anodes (DSA) have been used for the oxidation of aqueous solutions containing non biodegradable organics, such as pharma effluents.

Dimensionally stable anodes (DSA) are titanium substrates coated with a variety of oxide materials such as IrO2, Ru2, and SnO2. DSA with RuO2-TiO2 coated titanium has been used widely and successfully as an anode for Chlor-alkali production and electro-oxidation of wastewater due to its good electrocatalytic activity. RuO2 is a good electrocatalyst for oxygen evolution, in spite of limited service life.

The coating of RuO2 by thermal decomposition of the precursors such as RuCl3, can persist on titanium mesh surfaces for long durations and cause the activation of titanium anode through its pores. Surface activation by RuO2 can occur only if the coating is sufficiently porous for the diffusion of the ions involved during electro-oxidation. The coating also shows a high pseudocapacitance value due to the redox reactions of RuO2. At 400oC, the normal firing temperature of RuCl3 on titanium substrate, ruthenium penetrates deep into the bulk of the substrate and accumulates in the near surface region.

The Ti/RuO2 system has received considerable attention due to its excellent stability, electrocatalytic properties, and prevention of Ti passivation by the oxide coating. A further advantage is the large number of Ru-oxidation states existing at the electrode surface in the potential region between the hydrogen evolution reaction, HER, and the oxygen evolution reaction, OER. The electrochemical oxidation of organic substances was attributed to OCl−, OH−, nascent oxygen and other reactive.

Titanium-based anodes are unavoidable in electrooxidation techniques. This type of anode is mostly coated with catalytic oxides such as Ruthenium oxide or iridium oxide to enhance the oxidation process of the anode.