Assessing the Influence of the Presence of Heavy Metals Adsorbed on Activated Carbon on the Efficiency of Degradation of Phenol Using Selected Oxidizing Agents

Removing organic substances from wastewater is a complex problem. Different methods are used for this purpose. Recently, much attention has been given to the application of sorption and advanced oxidation processes (AOPs), which contribute also to the regeneration of activated carbon. The analysis presented in this paper focused on determining the influence of Cu(II) and Fe(II) ions adsorbed on activated carbon on the efficiency of oxidation of phenol by means of H₂O₂, Fenton's reagent Fe²⁺/H₂O₂ and 1:1 HNO₃ solution exposed to 2450 MHz microwaves, and, accordingly, the influence of Cu(II) and Fe(II) ions on the sorptive capacity of regenerated activated carbons. The results show that the chemical regeneration of activated carbon using AOPs resulted in partial oxidation of the adsorbed organic substance. The presence of Cu(II) or Fe(II) ions increased the regeneration efficiency. Using nitric acid to oxidize adsorbed phenol brought about a dramatic decline in the sorptive capacity of activated carbon with respect to this substance and an increase in the sorptive capacity of carbon with respect to metal ions. A serious drawback of this method, however, is that the oxidation of adsorbed phenol caused a significant loss of mass of activated carbon regardless of the oxidizing agent used.