Electrochemical processes in macro and microfluidic cells for the abatement of chloroacetic acid from water

• The electrochemical abatement of chloroacetic acid in water was studied.
• The performance of both macro and microfluidic reactors was examined.
• Cathodic reduction and anodic oxidation was studied in detail.
• Mediated oxidation by electro-Fenton and active chlorine was carried out.
• Anodic oxidation at BDD gave better performances.
• Microfluidic reactors gave better performances compared to conventional cells.

The remediation of solutions contaminated with monochloroacetic acid (CAA), which is one of the most resistant haloacetic acids (HAAs) to chemical degradation, dramatically depends on the adopted electrochemical approach: (i) CAA is only poorly oxidized either by homogeneous hydroxyl radical in electro-Fenton (EF), electrogenerated active chlorine or electro-oxidation on Pt anode; (ii) it is moderately abated by direct reduction on silver or compact graphite cathodes (from 30% in macro cells to 60% in the microfluidic devices); (iii) it is quantitatively removed by direct electro-oxidation on a boron-doped diamond (BDD) anode. The use of a microreactor enables operation in the absence of supporting electrolyte and drastically enhances the performance of the cathodic process. Simultaneously performing direct oxidation on BDD and reduction on graphite in a microfluidic cell yields the fastest CAA removal with 100% abatement at low current densities (∼5 mA cm−2).