Persulfate/electrochemical/FeCl2 system for the degradation of phenol adsorbed on granular activated carbon and adsorbent regeneration

A novel method was developed for phenol degradation and the regeneration of phenol-saturated granular activated carbon (GAC) in bench-scale tests. The degree of phenol degradation in solutions was as high as 75.3% when using persulfate/electrochemical/FeCl2 (PS/Electro/Fe) system under optimal conditions (1000 mg/L Na2S2O8 and 500 mg/L FeCl2 at 15 V). Based on these results, the regeneration of phenol-saturated GAC was then examined by the PS/Electro/Fe method. The highest regeneration efficiency of 58.2% was obtained when 30 g phenol-saturated GAC was treated in 1000 mg/L FeCl2 and 2000 mg/L PS at an applied voltage of 22.5 V. The effects of electric voltage and initial PS concentrations on the regeneration efficiency were examined in detail for the PS/Electro/Fe system. Considering the practical application of this method, multiple regenerations and reuse cycles of the phenol-saturated GAC were conducted, affording a regeneration efficiency of more than 40% after 3 cycles in practice.