In-situ regeneration of permeable reactive barriers via the electrokinetic process for phenol-contaminated groundwater remediation

Phenol contamination poses a significant challenge for groundwater remediation, while the limited longevity of permeable reactive barriers (PRBs) remains a major obstacle to their long-term application. This study evaluates an in-situ electrokinetic (EK) regeneration approach for PRBs treating phenol under continuous-flow conditions and simultaneously investigates regeneration efficiency, PRB longevity, and intermediate by-product formation. Experiments were conducted using a continuous glass reactor consisting of a granular activated carbon (GAC) bed positioned between two graphite electrodes. The effects of initial phenol concentration and influent flow rate on PRB performance were optimized, followed by assessment of EK regeneration performance. Optimal PRB operation was achieved at an initial phenol concentration of 150 mg L −1 and a flow rate of 20 mL min −1 . Increasing the applied voltage improved regeneration efficiency, and considering both longevity and energy consumption, 15 V was identified as optimal, restoring up to 86% of the adsorbent capacity within 5 h. Regeneration was confirmed by SEM imaging and nitrogen adsorption–desorption analysis. Under optimal conditions, EK integration extended operational longevity by up to 2.75 times compared with PRB alone. During regeneration, benzoquinone was detected as an intermediate product, whereas hydroquinone was not observed. The results demonstrate the potential of in-situ EK regeneration to extend PRB operational longevity; however, the limited number of regeneration cycles and the formation of benzoquinone indicate that further techno-economic assessment and field-scale validation are required.