| Magnetite(Fe3O4)is widely existed in nature,and Fe2+/Fe3+ is continuously converted on its surface,Therefore,Fe3O4 is a good heterogeneous Fenton catalyst.However,due to its own magnetic effect,Fe3O4tends to gather together in the reaction process,covering the active sites on the surface and inhibiting the catalytic activity.For this reason,biochar(BC),which is widely used,inexpensive,and easy to prepare,is used as a carrier to support Fe3O4 to inhibit its agglomeration during the reaction,and the active sites are exposed,thereby improving the catalytic activity of Fe3O4.In this paper,nanoFe3O4-biochar(Fe3O4/BC)and CuO-Fe3O4-biochar(CuO-Fe3O4-BC)heterogeneous catalysts were synthesized by coprecipitation method.The samples were characterized by various characterization methods,and the reaction process and mechanism of heterogeneouscatalyst adsorption and synergistic catalysis for the removal of bisphenol A(BPA)were studied.The following conclusions were obtained:1?The biochar obtained by the pyrolysis of deciduous leaves of Platanus orientalis has excellent physical and chemical properties,which provides conditions for better loading of Fe3O4.Fe3O4-BC nanocomposites were synthetized successfully by one-step coprecipitation method.2?The ability of Fe3O4-BC to catalyze PMS is much greater than that of Fe3O4.That may be due to the adsorption of biochar promoted the contact between catalyst and PMS as well as radicals and BPA,and the increased utilization efficiency of Fe3O4-BC catalyst and SO4·-.Lowering the initial pH and increasing the catalyst load and PMS concentration within a certain range can increase the removal efficiency of BPA.3?There are two kinds of free radicals(SO4·-and ·OH)in the Fe3O4-BC/PMS degradation system,both of which can degrade BPA.SO4·-is the major radical species4?Under the condition of external magnetic field,the material can be easily separated from the aqueous solution.In different initial pH systems,the concentration of iron ions precipitated after reused 5 times didn't exceed 3 mg/L.The cycle experiment further proves that the Fe3O4-BC material has good repeatability and stability and have broad prospects in practical applications.5?In CuO-Fe3O4-BC system,the addition of CuO allowed to achieve a high removal efficiency of BPA in a wide pH range,which overcoming the shortcomings of traditional Fenton reactions that must be carried out under strong acid conditions.Moreover,the catalyst has the best removal efficiency under neutral conditions.The solution pH can be not adjusted before reaction.so the cost is reduced and the subsequent treatment process is saved.6?The removal rate of BPA increases as the amount of catalyst increases.Increasing the PMS concentration within a certain range,the removal rate of BPA also increases.After exceeding a certain PMS concentration,it will inhibit even SO4·-and reduce the removal rate of BPA.7?The synergistic effect of copper ions and iron ions accelerates the circulation of Fe(?)/Fe(?)and Cu(?)/Cu(?).thereby accelerating the electron transfer on the catalyst surface and increasing the generation of free radicals rate.The adsorption of biochar pairs promotes the contact and reaction of BPA molecules with free radicals,further improving the removal rate of BPA.CuO,Fe3O4 and BC achieved a synergistic effect between adsorption and catalysis. |
PDF Full Text Request