Study On Active Electrolytic Manganese Anode Slag For Catalytic Degradation Of 4-chlorophenol

Electrolytic manganese anode slag（EMAS）contains more than 40%of Mn.However,at present,there is no mature recycling system in China,a large amount of EMAS is piled up,causing the waste of resources and threatening the environment,so the resource utilization of EMAS has attracted much attention.Mn is a very effective transition metal element for activating persulfate.Therefore,EMAS is a potential persulfate activator.In this research,it was first proposed to use EMAS as a catalyst to activate peroxymonosulfate（PMS）to degrade4-chlorophenol（4-CP）.This not only can effectively utilize EMAS,but also can achieve the purpose of"waste treatment by waste",which is a win-win strategy of economic and environmental benefits.The main contents and conclusions of this study are as follows:（1）EMAS has been significantly improved in catalytic activity after pickling activation,and metal leaching is reduced.XRF,BET,SEM,H₂-TPR and other technologies were used to characterize the catalyst.It was found that pickling can effectively remove inorganic components such as S,Mg,and Ca in the EMAS,while ensuring the stable existence of the active ingredients Mn and heavy metals Pb,making them difficult to be leached during the reaction.Pickled electrolytic manganese anode slag（PEMAS）exhibits richer pore structure,with specific surface area increased by 53%,the Mn dispersion of surface increased,and the pH_zpc increased from 4.20 to 5.96.These changes in surface morphology and properties contribute to the improvement of their catalytic activity.（2）The degradation of 4-CP in the PEMAS/PMS/4-CP system conforms to a first-order reaction kinetic model.Under the condition of 4-CP dosage of 40 ppm,PMS concentration of1 m M,catalyst dosage of 0.3 g/L,85%of 4-CP can be degraded within 50 min.（3）The PEMAS/PMS/4-CP system can maintain high-efficiency degradation of 4-CP in a wide range of pH.In the effects experiments of external factor,H₂PO₄^-will inhibit the degradation of 4-CP,while the influence of Cl^-,HCO₃^-and HA is slight,indicating that the PEMAS/PMS/4-CP/system can maintain effective in a wide range of water quality conditions.（4）The main active species of the PEMAS/PMS/4-CP system were O₂^·-and ¹O₂,of which some O₂^·-contributed to the production of ¹O₂,and another part O₂^·-directly contributed to the degradation of 4-CP,and also produced a small amount of·OH and SO₄^·-.During the reaction,the valence state of Mn exists Mn（III）/Mn（IV）and Mn（II）/Mn（III）transitions and it can keep cycling.（5）The biotoxicity experiment showed that after the reaction,the residual toxicity of the system is low.The PEMAS has good reusability.After 4 cycles of use,the PEMAS can still degrade 80.1%4-CP,and the crystal structure can keep stable after reaction.And it can keep low metal leaching in a wide range of pH,showing the superior stability of PEMAS.