铁锰氧化物改性铝污泥对Pb^(2+)和Cu^(2+)的吸附性能

Adsorption of Pb^(2+) and Cu^(2+) on alum watertreatment residuals modified by iron manganese oxides

【目的】以陕西杨凌某自来水厂铝污泥(Al-WTRs)为原料,对其进行改性,研究改性后铝污泥对Pb^(2+)和Cu^(2+)的吸附性能,以期为Al-WTRs的利用提供途径。【方法】采用KMnO_4和FeCl_2·4H_2O对Al-WTRs进行改性,制备铁锰氧化物改性铝污泥(M-Al-WTRs),采用比表面(BET-N2)、扫描电镜(SEM-EDS)、X射线衍射(XRD)、红外光谱(FTIR)等方法对改性前后Al-WTRs进行表征分析,并探讨不同pH、吸附时间、重金属初始质量浓度、温度和离子强度等条件下M-Al-WTRs对Pb^(2+)和Cu^(2+)的吸附性能。【结果】与Al-WTRs(9.10m^2/g)相比,M-Al-WTRs比表面积显著增大到100.8m^2/g;SEM-EDS、XRD、FTIR分析结果显示,M-Al-WTRs表面粗糙,且负载许多颗粒,并保持无定形态。M-Al-WTRs对Pb^(2+)和Cu^(2+)的吸附量随着pH的增加逐渐增大,最终趋于稳定,其中当pH=5时,M-Al-WTRs对Pb^(2+)和Cu^(2+)的吸附量分别为67.18和20.81mg/g,分别比Al-WTRs提高了109.1%和68.64%。M-Al-WTRs对Pb^(2+)和Cu^(2+)的吸附动力学符合准二级吸附动力学模型,吸附等温线符合Langmuir等温模型。热力学分析表明,M-Al-WTRs对Pb^(2+)和Cu^(2+)的吸附是自发、吸热、增熵的过程。M-Al-WTRs对Pb^(2+)和Cu^(2+)的吸附几乎不受离子强度的影响,属于专性吸附。【结论】成功制备了对Pb^(2+)和Cu^(2+)具有良好吸附效果的M-Al-WTRs。

【Objective】The adsorption of Pb2+and Cu2+on modified alum water treatment residuals were investigated to improve the utilization of Al-WTRs.【Method】Al-WTRs from a water plant in Yang ling,Shaanxi were modified by KMnO4and FeCl2·4H2O to obtain M-Al-WTRs.Adsorbents(Al-WTRs and M-Al-WTRs)were characterized by BET-N2,SEM-EDS,XRD and FTIR.Batch adsorption experiments were conducted to investigate the effects of pH,adsorption time,initial mass concentration of heavy metals,temperature and ion strength on adsorption properties of Pb2+and Cu2+by M-Al-WTRs.【Result】Compared with Al-WTRs(9.10m2/g),specific surface of M-Al-WTRs was significantly increased to 100.8m2/g.SEM-EDS,XRD,and FTIR showed that the surface of M-Al-WTRs was rough and loaded with many particles,and the amorphous structure was well maintained after modification.Adsorption capacities of Pb2+and Cu2+on M-Al-WTRs increased with increasing pH and reached steady gradually.When pH=5,the adsorption capacities of Pb2+and Cu2+on M-Al-WTRs were 67.18and 20.81 mg/g,which were109.1%and 68.64%higher than that of Al-WTRs,respectively.The adsorption of Pb2+and Cu2+by M-Al-WTRs could be described with the pseudo-second-order kinetic model,and the adsorption isotherm fitted Langmuir model well.Thermodynamic analysis showed that the adsorption process of Pb2+and Cu2+on M-Al-WTRs was spontaneous,endothermic and entropy increasing.The adsorption of Pb2+and Cu2+on M-Al-WTRs was hardly affected by ionic strength.【Conclusion】M-Al-WTRs with relative good adsorption capacities of Pb2+and Cu2+could be prepared by alum water treatment residuals.