Laboratory pre-assays for soil remediation by electro synthesis of oxidants and their electrokinetic distribution

Abstract

The feasibility of an innovative electrokinetic soil remediation technique for an in situ application against fuel-contaminated soil has been studied in this work. This technique combines the anodic production of oxidizing agents on boron-doped diamond (BDD) electrode surfaces with their electrokinetic distribution in soil. In this study, the production of oxidizing agents, i.e., hydroxyl radicals (OH°) and peroxodisulfate (S₂O₈ ^{2 −}), from a 0.85 M sodium sulfate electrolyte with mechanically implanted BDD anodes at room temperature has been investigated. It was found that about 12 mmol/L of oxidants could be produced after 10 Ah/L with a current density of 200 mA/cm². For investigating the transport velocity of peroxodisulfate in soil a vertical column system has been created. Experimental results show linear velocity behaviour for the oxidants' migration in 100% sand soil reaching up to 2 cm/h at an electrical gradient of 4 V/cm. As for different soil textures which have been tested, the assays stated that the highest velocity can be achieved in a 100% silt soil with 3.3 cm/h.

Keywords:

• Electrokinetic remediation
• BDD electrode
• peroxodisulfate
• in situ oxidation
• ion distribution

Acknowledgment

This work was funded by the Kommunalkredit Public Consulting, Austria Foundation.