In Situ Generation Of Reactive Oxygen Species On The Interface Of Zerovalent Aluminum And Oxygen And Its Application To The Removal Of Aqueous Acetaminophen

The removal of organic compounds by advanced oxidation processesgenerally involves the generation of reactive oxygen species （ROS）. Is itpossible to develop a method that can generate ROS like the biologicalreactions occurred in organisms? Although the generaltion of ROS by somereactive zerovalent metals was previously studied, the mechantic informationon the formation of ROS is poorly understood. In this study, we investigatedthe in situ generation of ROS on the interface of zerovalent aluminum （ZVAl）and oxygen and its application to the oxidative removal of aqueousacetaminophen （ACTM）.（1） We evaluated the efficay and influencing factors for the removal ofACTM by ZVAl/O₂system. Overall, in pH <3.5acidic solutions ZVAl/O₂system demonstrated an excellent capacity to remove ACTM. More than99%of ACTM was eliminated within16h in pH1.5reaction solutions initiallycontaining2.0g/L aluminum and2.0mg/L ACTM at25±1°C. Highertemperature and lower pH facilitated ACTM removal. No ACTM removalwas observed when pH was>3.5. Low concentrations （<1.0mg/L） of humicacid had negligible effect on ACTM removal.（2） The in situ generation of ROS on the interface of ZVAl and oxygenwas investigated via the determination of formation H₂O₂. Under pH1.5and 2.5conditons, H₂O₂was generated up to³30μM. The oxidativeintermediate hydroquinone was identified via GC-MS analysis, and the anionsformate, acetate and nitrate were detected via ion chromatographic analysis.On the basis of the identified intermediate or products, the possible pathwaysfor the removal of ACTM by ZVAl/O2system were proposed.（3） We also investigated the methods to enhance the generation of ROSby ZVAl/O2system. Results showed that he addition of different iron speciesFe⁰, Fe²⁺and Fe³⁺into the system dramatically accelerated the reaction likelydue to the enhancing transformation of H₂O₂to HO via Fenton’s reaction.This work suggests that ZVAl/O2system may be potentially employed totreat wastewater containing high concentrations of organic contaminants.