Electrochemical activation of sulfate
Electrochemically produced sulfate radicals enhance drastically the removal of persistent organic contaminants from water.

In recent years, innovative oxidation technologies based on the generation of strong oxidant species, sulfate radicals (SO4-, E0=2.5-3.1 V), have obtained great scientific and technological interest for wastewater treatment and in situ chemical oxidation (ISCO). Sulfate radicals are typically produced by the activation of persulfate (S2O82-) and peroxymonosulfate (HSO5-) using heat, UV, alkali or transition metal catalysis. However, these activation methods are highly impractical for the field application of persulfate.

Studies conducted recently at the Advanced Water Management Centre (AWMC, Australia) and here at the Catalan Institute for Water Research, show that sulfate radicals can also be generated by electro-oxidation at boron doped diamond (BDD) anodes, directly from sulfate ions. Electrochemical activation of sulfate at BDD electrodes may have significant implications in the treatment of sulfate-containing waters, and it may be a feasible alternative to persulfate injection in ISCO treatment of groundwater. By placing an electrochemical reactive barrier, sulfate present in contaminated groundwater plume can be activated to degrade persistent organic contaminants.

In this project, we are investigating the mechanisms of sulfate radical generation at BDD and other anode materials, their participation in the degradation of organic contaminants and in the anodic formation of persulfate. Furthermore, we are interested in the effect that the organic and inorganic matrix have on the SO4--mediated electro-oxidation of contaminants.