Electrochemical degradation of ibuprofen-contaminated soils over Fe/Al oxidation electrodes

Highlights: • The developed Fe/Al electrodes presented up to 94.6% of IBP degradation. • Aluminum plays as an electron donner to trigger Fenton–like reaction to produce OH• . • Providing H₂O₂ and prolonging treatment time notably enhanced IBP degradation. • Increasing electrode area was only favored for the removal mechanism of IBP. • Five reaction mechanisms were clearly provided in this study. Ibuprofen (IBP) is one of the most known non-steroidal anti-inflammatory drugs. Due to the high consumption and the several ways of discharge, both the aquifer and soil matrix were contaminated by IBP. This study examined the degradation of the IBP in a soil matrix over Fe/Al oxidation electrodes in an electrokinetic system with processing fluids of sodium dodecylsulfate (SDS). The preparation of the Fe/Al oxidation electrode was carried out at a calcination temperature of 500, 550, and 600 °C, which accounted for Fe³⁺ coating rate of 3.89 ± 0.03%, 4.62 ± 0.04%, and 4.72 ± 0.04%, respectively. Results indicated the generation of hydroxyl radical was proportional to the coating rate of Fe³⁺ on the electrode. A 200 mg kg⁻¹ of IBP-spiked soil sample was conducted in an electrokinetic system under a potential gradient of 2 V cm⁻¹. The experimental parameters included electrode area of 11–33 cm² and treatment time of 5–9 days. The remediation efficiency of IBP in the EK systems coupled with Fe/Al oxidation electrode was 70.1–94.6%, which was highly dependent on H₂O₂ addition, electrode area, and treatment time. Both addition of H₂O₂ and prolonging treatment time significantly enhanced the degradation of IBP. Whereas increasing electrode area was only favorable for removal mechanism of IBP. Five reaction mechanisms were clearly provided in this study. The aluminum plays an electron donner to trigger Fenton–like reaction continuously to produce hydroxyl radicals. This study confirmed that the electrokinetic process coupled with Fe/Al oxidation electrodes is a viable technique for the remediation of IBP-contaminated soil. Make good use of redox characteristic of aluminum to trigger the Fenton-like reaction in Fe²⁺-rich environment is a great success in this study. The use of Fe/Al electrodes effectively expands the application of electrochemical degradation in soil remediation.