Degradation Of Bisphenol By Peroxymonosulfate Activated With CoFe₂O₄,CuCo₂O₄ And Composite Material Loading Carbon Material:efficiency And Mechanisms

Bisphenol A（BPA）is a typical environmental endocrine disruptor with stable physicochemical properties,toxic and difficult to degrade.Recent studies have shown that advanced persulfate oxidation technology can utilize the strong oxidizing power of sulfate radicals(SO₄^·-)to degrade BPA in water with good removal effect and almost no secondary pollution.Therefore,this study aims to prepare an efficient metal oxide catalyst activated permonosulfate（PMS）to degrade BPA in water,and combine it with carbon nanotubes（CNT）and graphene（GO）to further improve the activation with PMS and degrade BPA in a short time.In this study,CoFe₂O₄and CoCu₂O₄were prepared by sol-gel method,and the composite materials of CoFe₂O₄/CNT,CoCu₂O₄/CNT,CoFe₂O₄/GO and CoCu₂O₄/GO were prepared by hydrothermal method.X-ray diffraction spectroscopy（XRD）,scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）and other analytical methods were used to characterize the structure and morphology of the catalyst.After the metal oxide is loaded with carbon material,its specific surface area has been greatly increased,which is conducive to the full contact of the catalyst with PMS molecules and organic pollutants,thereby enhancing the purpose of the catalyst to activate PMS to degrade BPA.When the concentration of BPA was 0.1 m M and the p H of the solution was 7.0,the degradation rate of BPA reached 68%and 82%after 25 minutes after adding 100mg/L CoFe₂O₄and CoCu₂O₄and 0.2 m M PMS solution.While,the degradation of BPA is negligible in PDS and H₂O₂systems.The efficiency of the catalyst to activate PMS to degrade BPA is affected by p H.The degradation efficiency of BPA increases with the p H of the solution increases from 3.6 to 7.0,but when the p H of the solution further increases,the degradation of BPA is inhibited,which indicating that both catalysts reached the highest degradation rate at neutral p H.As the catalyst dosage increaseing,the degradation rate of BPA increased;as the catalyst dosage increases,the degradation rate of BPA increases;in addition,the degradation rate of PPA in actual water after 25min catalyzed by CoFe₂O₄and CoCu₂O₄was 56%and 64%,respectively.The degradation effect of BPA was reduced to a certain extent after four cycles of CoFe₂O₄and CoCu₂O₄,but it was still able to Maintain 49%and 75%degradation efficiency.It was found that both SO₄^·-and·OH participated in the activation process,of which SO₄^·-was the main reactive free radical to participate in the reaction through the capture of free radicals and EPR detection.Besides,the CoFe₂O₄/PMS and Cu Co₂O₄/PMS systems maintain a high degree of mineralization of BPA degradation,and the toxicity of the reaction system eventually decreases during the BPA degradation by the detection of total organic carbon and toxicity of the reaction process.After CoFe₂O₄and CoCu₂O₄support carbon materials,the degradation efficiency of BPA has been significantly improved.Through the experiment on the influence of the ratio of the carbon material loaded,it is found that when the carbon material load ratio is 20%,the catalytic effect is the best.Among them,the effect of metal oxide loading with graphene is better than carbon nanotubes and CoCu₂O₄/GO has the best catalytic effect.The reaction rate constants of 100 mg/L CoFe₂O₄/CNT,CoCu₂O₄/CNT,CoFe₂O₄/GO and CoCu₂O₄/GO to degrade BPA were 0.227,0.140,0.330 and2.662 min^-1,respectively,which were higher than the reaction rate constants 0.064 and0.074 min^-1of CoFe₂O₄and CoCu₂O₄by PMS.Since CoFe₂O₄and CoCu₂O₄are loaded with carbon materials,the catalytic performance has been greatly improved.BPA could maintain a high degradation effect in water and there was almost no effect on the degradation of BPA catalyzed by CoFe₂O₄/GO and CoCu₂O₄/GO.Besides chloramphenicol can also be effectively degraded.The degradation efficiency of chloramphenicol is further improved with the increase of PMS dose,which showed that CoFe₂O₄,CoCu₂O₄and the composite materials with CNT or GO can also be applied to the degradation of other organic pollution by PMS.The degradation experiments of BPA by CNT and GO indicate that CNT and GO alone mainly degraded BPA in water by the adsorption of carbon materials.CNT and GO cannot effectively catalyze PMS to generate active free radicals.While,PMS could generate active radicals mainly by the metal oxide loaded with the carbon materialdue.The loading of the carbon material improved the ability of the metal oxide to gain and lose electrons,which made the ability to degrade BPA by PMS is greatly enhanced.