磁改性生物质炭渣对酸性矿山废水中Cu^(2+)、Pb^(2+)的吸附研究

Adsorption characteristics of Cu^(2+)and Pb^(2+)in acid mine wastewater by magnetic modified biomass residue

针对酸性矿山废水(Acid Mine Drainage, AMD)中Cu^(2+)和Pb^(2+)含量过高,生物质炭渣吸附能力有限等问题,以工业固体废弃物生物质炭渣为原材料,采用高锰酸钾和硫酸亚铁对生物质炭渣进行磁改性,制备生物质炭渣负载MnFe_(2)O_(4)的复合磁性材料(BC-MF),并将BC-MF作为去除酸性矿山废水环境中Cu^(2+)和Pb^(2+)的吸附剂。基于单因素试验方法,探究pH值、温度、初始质量浓度、吸附时间、共存金属离子等因素对BC-MF吸附Cu^(2+)和Pb^(2+)性能的影响,并将吸附动力学、吸附热力学、吸附等温线与扫描电子显微镜(Scanning Electron Microscopy, SEM)、X射线衍射(X-ray Diffraction, XRD)、傅里叶变换红外光谱(Fourier Transform Infrared Spectroscopy, FT-IR)、磁滞回线测试(Vibrating Sample Magnetometer, VSM)、Zeta电位(Zeta potential)等表征方法结合,研究MnFe_(2)O_(4)磁改性生物质炭渣吸附Cu^(2+)、Pb^(2+)的机理。结果显示,改性后的BC-MF对Cu^(2+)和Pb^(2+)的去除率均提升20百分点以上,且吸附饱和质量比分别为18.04 mg/g和24.98 mg/g。表征结果显示:MnFe_(2)O_(4)磁性颗粒成功负载到BC-MF上,并使之具有磁性;BC-MF对Cu^(2+)和Pb^(2+)吸附过程均符合Langmuir等温吸附方程和准二级动力学模型,吸附过程是为化学吸附为主的单层均相吸附;热力学结果表明该吸附过程属于自发进行的熵增过程。

In this study,a composite magnetic material(BC-MF)of biomass charcoal slag loaded with MnFe_(2)O_(4) 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 Cu^(2+)and Pb^(2+)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 Cu^(2+)and Pb^(2+)were investigated based on the one-factor experimental method.The adsorption mechanisms of Cu^(2+)and Pb^(2+)on MnFe 2O 4 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 Cu^(2+)and Pb^(2+)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 Cu^(2+)and Pb^(2+)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 Cu^(2+)and Pb^(2+)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 MnFe 2O 4 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 Cu^(2+)and Pb^(2+)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 Cu^(2+)and Pb^(2+)from AMD.