巯基功能化纳米Fe_3O_4-高分子磁性复合材料的合成及其对水中亚甲基蓝的吸附作用

Preparation of thiol-functionalized nano-Fe_3O_4-polymer magnetic composite and its adsorption properties on methylene blue in water

采用悬浮聚合法制备了巯基功能化纳米Fe3O4-高分子磁性复合材料（SH-nFe3O4-polymer）。通过TGA、EA、AAS、XRD、FTIR、TEM、VSM等手段对合成的SH-nFe3O4-polymer进行了组成、结构、形貌、磁性等表征,并研究了其吸附和去除水中亚甲基蓝（MB）染料的性能。结果表明：合成的SH-nFe3O4-polymer平均粒径为250～300nm,饱和磁化强度为5.88emu/g;SH-nFe3O4-polymer对MB的等温吸附线符合Langmuir模型,饱和吸附量为476.2mg/g,高于四乙烯五胺功能化纳米Fe3O4-高分子磁性复合材料（TEPA-nFe3O4-polymer,30.6mg/g）和不含磁核的巯基功能高分子材料（SH-polymer,74.6mg/g）。吸附热力学研究表明,SH-nFe3O4-polymer对MB的吸附过程是自发的吸热熵增过程;吸附动力学研究表明,吸附过程可在10min内达到平衡,符合准二级动力学模型;其吸附过程的活化能为9.53kJ/mol。SH-nFe3O4-polymer能有效去除水中的MB,其对MB的吸附机理涉及静电相互作用、π-π相互作用和疏水相互作用;磁核的存在可以形成微电场,有利于加速吸附过程的传质,确保吸附过程快速有效地进行。

The thio-functionalized nano-Fe3O4-polymer magnetic composite material（SH-nFe3O4-polymer）was synthesized via suspension polymerization.The SH-nFe3O4-polymer was characterized by TGA,EA,AAS,XRD,FTIR,TEM and VSM.The application for its adsorption properties on the methylene blue（MB）from water was investigated.The results show that the SH-nFe3O4-polymer has an average size of 250-300nm,with the saturation magnetization intensity of 5.88emu/g.The adsorption capacities were investigated by adsorbing the MB from aqueous solutions,which demonstrate an excellent adsorption capacity with the maximum adsorption capacity at 476.2mg/g,much higher than those of the tetraethylenepentamine-functionalized nano-Fe3O4-polymer magnetic composite（TEPA-nFe3O4-polymer,30.6mg/g）and the thiol-functionalized polymer free of magnetic core（SH-polymer,74.6mg/g）.The isothermal adsorption curve mainly obeys the Langmuir mode.The adsorption thermodynamic studies suggest that the adsorption processes of the MB by the SH-nFe3O4-polymer are endothermic,entropy favored,and spontaneous in nature.The adsorption kinetic studies show that the adsorption processes reach the equilibrium within 10min and the kinetic data are well fitted to the pseudo-second-order model.The activation energy for the MB removal is found to be 9.53kJ/mol.The MB in aqueous solution can be effectively removed by the SH-nFe3O4-polymer.The primary mechanism studies reveal that the adsorption processes may be related to the electrostatic attraction,π-πand hydrophobic interactions between the MB and the SH-nFe3O4-polymer.The existing of the magnetic coremight be favorable to the mass transfer thus accelerating the adsorption process.