Fabrication Of Ferrite/sludge-derived Activated Carbon Composites And Its Application In Advanced Oxidation Method

In advanced oxidation process,sulfate radical?SO₄^-·?based oxidation system has become the focus of current research due to its strong and fast oxidation ability,high degree of pollutant mineralization and wide pH applicability.At present,the studies of SO₄^-·have focused on the preparation of recyclable catalysts,the optimization of reaction conditions,the improvement of catalyst regenerability and the study of reaction mechanism,etc.Based on it,this study two common contaminants in wastewater,dye Orange G?OG?and antibiotics Norfloxacin?NOR?were proposed as target pollutants.We synthesized the sludge base activated carbon?SAC?and spinel ferrite?MFe₂O₄?composite as catalyst,and the two kinds of pollutants are respectively degraded by the heterogeneous sulfate radical system.Several characterization techniques such as XRD,FTIR,SEM and XPS indicated the successfully synthesis of SAC/MnFe₂O₄ and SAC/CoFe₂O₄ through hydrothermal method and solvothermal method,respectively.The SAC/MnFe₂O₄ composite exhibited excellent catalytic activity in the activation of peroxysulphate?PS?,which could efficiently degrade OG in the range of pH 3-9,and the reaction rate decreased with the increasing of p H value.Within the experimental temperature from 15?to 55?,the OG degradation rate increased with the increasing temperature.In addition,the catalyst still maintain satisfactory activation activity after five cycles,combining with the heavy metal leaching experiment results,showed that the SAC/MnFe₂O₄ catalysts have excellent catalytic and structural stability.In the reaction of the SAC/MnFe₂O₄-PS system,two free radicals HO·and SO₄^-·were both invloved,but the latter played a dominant role.it is noteworthy that OG degradation reaction occurred at the near surface of the catalyst.During the experiments of SAC/CoFe₂O₄ catalyzing peroxymonosulfate?PMS?to degrade NOR,NOR can be completely degraded within 60 min in the range of pH=5⁹.However,under the condition of strong acid or strong alkaline,the degradation efficiency of NOR expressed varying degrees of inhibition.The influence of coexisting anions on the catalytic reaction:Cl^->HCO₃^->NO₃^-?After five consecutive cycles,the degradation rate of NOR with SAC/CoFe₂O₄-PMS system was still more than 90%,indicating that the catalyst had great regeneration performance and catalytic stability.In the study of reaction mechanism,the dominant free radical was not·OH but SO₄^-·.In addition,the ion fragments in the solution was determined by LC-MS,and the degradation path of NOR in the system was proposed,including piperazine ring cleavage,decarbonization and defluorination reaction.This study provided a new way for resource utilization of excess sludge,and constructed an environmental friendly heterogeneous sulfate radical oxidation technology for efficient degradation of dyes and antibiotic.Therefore,this study has both theoretical guidance and practical significance.