Adsorption characteristics of Cu2+and Pb2+in acid mine wastewater by magnetic modified biomass residue
In this study,a composite magnetic material(BC-MF)of biomass charcoal slag loaded with MnFe2O4 was prepared from industrial solid waste-biomass charcoal slag as raw material by using potassium permanganate and ferrous sulfate to magnetically modify the biomass charcoal slag,which was aimed to be used as an adsorbent for enhancing the removal rate of Cu2+and Pb2+from AMD on the one hand,and on the other hand,it could achieve the resourcefulness of large amount of biomass charcoal slag,which is a huge quantity of industrial solid waste produced by biomass cogeneration power plants.The effects of pH,temperature,initial concentration,adsorption time,and co-existing metal ions on the performance of BC-MF for adsorption of Cu2+and Pb2+were investigated based on the one-factor experimental method.The adsorption mechanisms of Cu2+and Pb2+on MnFe2O4 magnetically modified biochar residue was investigated by adsorption kinetics,adsorption thermodynamics,adsorption isotherms,and characterization methods such as SEM,XRD,FT-IR,Zeta and VSM.The results show that the adsorption of Cu2+and Pb2+by BC-MF increases by more than 20％with adsorption capacities of 18.04 mg/g and 24.98 mg/g,respectively,following the Langmuir isothermal adsorption equation and the quasi-secondary kinetic model.The adsorption process is a monolayer homogeneous adsorption dominated by chemisorption.The thermodynamic results show that the adsorption process is a spontaneous entropy-increasing process.Repeatability experiments show that the adsorption of Cu2+and Pb2+by BC-MF still maintains a certain adsorption effect after five repetitive application tests,and there is almost no dissolution of heavy metal ions other than Cu2+and Pb2+during the cyclic adsorption process,indicating that the BC-MF composite magnetic material has a certain recycling and reuse value.Characterization techniques show that the MnFe2O4 magnetic particles are successfully loaded onto BC-MF,which gives it a magnetically developed pore structure,abundant adsorption sites,active participation of some active groups in the adsorption reaction,etc.The adsorption mechanisms of BC-MF on Cu2+and Pb2+mainly include electrostatic attraction,ion exchange,and surface complexation.In conclusion,this study provides a feasible way for the resource utilization of industrial solid waste-biomass residue to achieve the removal of Cu2+and Pb2+from AMD.
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